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Eagle, Dawn Marie. "Grouping behaviour as a defence against predation in whirligig beetles." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321178.
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Warzée, Nathalie. "Prey unpredictability and unfavourable host trees influence the spatial distribution of the polyphagous predator Thanasimus formicarius (L.), Coleoptera :Cleridae." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211012.
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Polyphagy is a very common trait among insects. In this study, we focus on a generalist bark-beetle predator, Thanasimus formicarius (L.) (Coleoptera, Cleridae), which feeds on many scolytids in spruce, pine and broad-leaf stands. It is known to respond to the pheromones of many scolytids, among which the most harmful spruce bark beetle in Europe, Ips typographus (L.). The adults attack scolytid adults and oviposit on attacked trees where their larvae feed upon immature stages of the prey. <p>However, a bottom-up process limits Thanasimus formicarius’ impact on spruce bark beetles, because in most cases the bark of spruce is too thin for sheltering pupal niches and mature larvae have to leave the trees. On pine however, pupation is quite successful and reproductive success is high. <p><p>The present work estimates the advantages (complementary prey during gaps among the phenology of pine bark beetles or due to the population fluctuations of most scolytids) and constraints (landing on unsuitable host trees for the predator’s reproduction) for T. formicarius to have a wide range of prey. <p><p>Passive barrier-trappings showed that the presence and abundance of scolytid species vary strongly from year to year. So, polyphagy in T. formicarius appears as a response to fluctuating prey supplies. <p><p>This way of foraging may lead T. formicarius towards stands not always favourable for its development (for example, spruces). <p>At the tree level, funnels and pitfall-traps caught high numbers of third-instar T. formicarius larvae walking on the bark surface of standing spruces infested by Ips typographus (respectively 365 and 70 L3s). After feeding into the whole infested part of the trunk, these larvae are obliged to migrate outside of the galleries to favourable pupation site (e.g. the base of the trees where the bark is thicker), or even to leave the trees and search for an acceptable pupation substrate in the litter. <p><p>At the landscape level, different trapping experiments showed a correlation between catches of T. formicarius and the proportion of pines around each trap. Consequently, in a metapopulation landscape pattern, pines would act as “sources” of predators, whilst spruces are “sinks”. Indeed, Thanasimus formicarius are trapped in higher numbers in mixed stands comprising pines. This observation is also corroborated in a four-year trapping experiment in the North-East of France, following the storms of December 1999. The predator/prey ratios (T. formicarius/I. typographus) were higher in stands comprising pines than in stands without pines. The first step of a method to estimate Ips typographus infestation trends thanks to the predator/prey ratios was also developed. <p><br>Doctorat en sciences, Spécialisation biologie animale<br>info:eu-repo/semantics/nonPublished
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Dohet, Loïc. "Coevolution in the specific predator-prey system Rhizophagus grandis-Dendroctonus micans: with emphasis on the predator’s oviposition kairomones and prey symbioses." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/232990.
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Rhizophagus grandis is one of the rare examples of totally specific predators: it only preys upon the bark beetle Dendroctonus micans in its native range (Europe and Asia). In the course of coevolution in such predator-prey systems, prey are selected for avoidance and resistance mechanisms against predators. Previous laboratory trials suggested that R. grandis could lay more eggs in presence of exotic prey species with an ecology similar to that of D. micans, but which could not evolve resistances against this predator, such as the North American parasitic bark beetles D. punctatus and D. valens. The specificity of the association R. grandis-D. micans is thought to depend on chemical signals (kairomones) used by the predator to find a gallery of its prey and to adjust its oviposition to the number of prey larvae available inside. However, the exact nature of the chemical signals regulating R. grandis’ oviposition is still unknown. While these signals seem specific in nature, stimulation of the predator’s oviposition by exotic prey species suggests that specificity may be constrained by geography. Unlike most bark beetles, which kill living trees or feed on dying trees, D. micans completes its development on healthy trees as a true parasite. This niche is highly defended by tree toxicants (terpenes among others) to which both D. micans and R. grandis are resistant. Insects possess their own detoxification processes, but they may also rely on symbiotic microorganisms (bacteria and fungi) to contend with the specific constraints of their niche. In comparison to other bark beetles, microbial communities of parasitic bark beetles are yet poorly known, as in the case of D. micans and D. punctatus. Apart from detoxification, insect symbionts may provide nutritional supplementation, protection against pathogens, or components of the chemical communication, which affect the hosts as well as partners of the tritrophic relationship tree-bark beetle-natural enemies. The system R. grandis-D. micans is a unique opportunity to study several aspects of this coevolution which are poorly understood to date. The objectives of this thesis were:- (1) the comparison of the oviposition performances of R. grandis on the specific prey D. micans, and on the exotic prey D. punctatus and D. valens, in order to emphasize possible prey resistance mechanisms; - (2) the identification of the chemical signals regulating R. grandis’ oviposition, and the evaluation of their role in the specificity of the association with D. micans, in presence of the exotic prey D. punctatus and D. valens; - (3) the characterization of the bacterial and fungal communities associated with non-aggressive populations of the bark beetles D. micans, D. punctatus and D. valens, and investigating how these microbial symbionts may affect bark beetle hosts in respect of their ecology as well as the tritrophic relationship tree-bark beetle-natural enemies. Our results show that R. grandis laid equivalent numbers of eggs with the native prey D. micans and with the exotic prey D. punctatus and D. valens, which could illustrate that R. grandis’ specificity is constrained by geography but which does not emphasize possible prey resistance mechanisms against the long-standing predator. We identified robust candidates to the stimulation and inhibition of R. grandis’ oviposition which should be confirmed in bioassays. Finally, we report that the bacterial and fungal communities of non-aggressive populations of D. micans, D. punctatus and D. valens are mainly composed of widespread environmental Enterobacteria and yeasts, and we discuss the various ways they may influence bark beetle hosts in respect of their life histories including the attacked trees and their natural enemies. Overall, this thesis illustrates the need to encompass all levels of complexity, from prey symbionts and semiochemicals to predators, to study systems like R. grandis-D. micans.<br>Rhizophagus grandis est un des rares exemples de prédateurs totalement spécifiques :présent en Europe et en Asie, il se nourrit exclusivement du scolyte Dendroctonus micans. Dans de telles associations, la coévolution prédateur-proie mène à la sélection de mécanismes d’évitement ou de résistance chez la proie, contre le prédateur. De précédentes observations en laboratoire ont suggéré que R. grandis pouvait pondre davantage d’œufs en présence de proies exotiques d’écologie comparable à celle de D. micans, mais qui n’auraient pu développer de résistance à l’encontre de ce prédateur, à l’instar des scolytes parasitiques nord-américains D. punctatus et D. valens. Il semble que la spécificité de l’association R. grandis-D. micans repose sur des signaux chimiques (kairomones) qui permettent au prédateur de repérer les galeries de sa proie et d’y ajuster le nombre d’œufs déposé à la quantité de larves de proies disponible. Néanmoins, on ignore encore la nature exacte des signaux régulant l’oviposition de R. grandis. Le fait que l’oviposition soit stimulée par des proies exotiques indique que la spécificité de cette association pourrait être limitée par des barrières géographiques. Contrairement à la plupart des scolytes qui tue des arbres ou s’attaque à des arbres mourants, D. micans se développe intégralement sur des arbres en bonne santé, en véritable parasite. Cette niche est fortement défendue par les composés toxiques de l’arbre (en particulier les terpènes), auxquels à la fois D. micans et R. grandis sont résistants. Certains insectes possèdent leurs propres processus de détoxification, mais ils peuvent également bénéficier de l’aide de microorganismes symbiotiques (bactéries et champignons). En comparaison avec les autres scolytes, les communautés microbiennes associées aux scolytes parasitiques est très peu documentée, comme dans le cas de D. micans et D. punctatus. En dehors de la détoxification, les symbiotes d’insectes peuvent contribuer à leur nutrition, les protéger contre des pathogènes, ou intervenir dans la communication chimique, ce qui affecte leurs hôtes comme les autres acteurs de la relation tritrophique arbre-scolyte-ennemi naturel. L’association R. grandis-D. micans est une opportunité unique d’étudier des aspects méconnus de la coévolution. Les objectifs de cette thèse étaient de :- (1) comparer le nombre d’œufs pondu par R. grandis sur sa proie spécifique, D. micans, et sur les proies exotiques D. punctatus et D. valens, afin de mettre en évidence de possibles résistances ;- (2) identifier les signaux chimiques qui régulent l’oviposition de R. grandis, et évaluer leur rôle dans la spécificité de l’association avec D. micans, en présence des proies exotiques D. punctatus et D. valens ;- (3) caractériser les communautés bactérienne et fongique associées aux populations parasitiques des scolytes D. micans, D. punctatus et D. valens, et investiguer comment ces microorganismes symbiotiques peuvent influencer leurs hôtes, selon leurs contraintes écologiques, ainsi que leurs ennemis naturels et arbres-hôtes. Nos résultats révèlent une oviposition équivalente de R. grandis en présence de la proie native D. micans et des proies exotiques D. punctatus et D. valens, ce qui illustre que la spécificité de cette association pourrait être limitée par des barrières géographiques mais ne met pas en évidence de possibles résistances à l’encontre du prédateur de longue date. Nous avons identifié des candidats robustes à la stimulation et à l’inhibition de la ponte de R. grandis, et leur rôle devrait être confirmé par des bioessais. Enfin, nous rapportons que la communauté microbienne associée aux populations parasitiques des scolytes D. micans, D. punctatus et D. valens est principalement constituée d’Entérobactéries et de levures répandues, et nous discutons des différentes façons dont ces symbiotes peuvent affecter leurs hôtes et autres acteurs de la relation tritrophique arbre-scolyte-ennemi naturel, selon leurs écologies respectives. Dans son ensemble, cette thèse souligne l’importance de considérer tous les niveaux de complexité biologique, des microorganismes associés aux proies jusqu’aux prédateurs, afin d’étudier des systèmes comme R. grandis-D. micans.<br>Doctorat en Sciences<br>info:eu-repo/semantics/nonPublished
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Deroulers, Paul. "Étude des interactions trophiques entre les communautés de carabes et de graines adventices sous l'angle d'un système proie-prédateur." Thesis, La Rochelle, 2017. http://www.theses.fr/2017LAROS030/document.
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La flore adventice est à la base des chaînes trophiques dans les agroécosystèmes. Leur diminution dans les parcelles cultivées est une des causes de la baisse de la biodiversité. Par conséquent, des alternatives sont étudiées pour diminuer l’utilisation des herbicides dans le cadre du plan ECOPHYTO. Par exemple, la gestion de la flore adventice via les consommateurs de graines. En effet, les agroécosystèmes sont des milieux où des espèces granivores ont les capacités de consommer les graines d’adventices. Parmi les vertébrés, nous pouvons y trouver des oiseaux (alouette des champs) ainsi que des micromammifères (mulot). Parmi les invertébrés, les carabes sont identifiés comme principaux granivores dans les agroécosystèmes tempérés. L’objectif général de cette thèse est d’étudier les interactions entre carabes et graines d’adventices afin d’apporter des connaissances sur les interactions interspécifiques et d’identifier les traits physiologiques des espèces influençant la force des interactions entre les espèces. Un protocole a été établi afin de standardiser toutes les expériences et de garder comme variables uniquement l’espèce de graines et celle du carabe. Ensuite, nous avons étudié les interactions entre les graines d’adventices et les carabes selon deux axes de recherche. Le premier a permis de comparer les niveaux de consommation de la communauté de carabes sur une même espèce de graines. Nous avons pu ainsi observer que la masse corporelle des carabes n’était pas en relation avec la variation des niveaux de consommation. Mais le ratio entre la longueur des mandibules et la largeur du labrum (force mandibulaire) a un effet significatif lorsque seules les espèces consommant plus de cinq graines sont prises en compte. Pour le deuxième axe, nous avons mesuré la consommation des carabes sur 42 espèces de graines pour identifier les capacités de consommation et explorer la stratégie d’alimentation selon deux caractéristiques : la masse des graines (taille) et leur concentration lipidique. Les graines de faibles masses avec un taux lipidique élevé sont mangées en plus grand nombre. Enfin, nous avons déterminé les types de réponse fonctionnelle pour évaluer le potentiel de régulation de 4 espèces de carabes sur deux espèces de graines d’adventices. Pour chaque espèce (mâle et femelle) nous avons trouvé une réponse fonctionnelle de type II, sauf pour les femelles de P.rufipes. Cependant nos résultats doivent être interprétés avec précaution car en milieu naturel d’autres facteurs interviennent dans les interactions, telle que la présence de proies alternatives ou d’autres prédateurs. En conclusion, nous montrons que les interactions entre les graines d’adventices et les carabes sont nombreuses et complexes. Les caractéristiques physiologiques intervenant dans les interactions sont très nombreuses et très variables selon les espèces. Des études supplémentaires sont nécessaires pour évaluer l’intérêt agronomique des carabes dans la gestion des adventices<br>Weed flora limits crop yields therefore herbicides inputs are important in order to manage weeds. Weeds are at the bottom of the trophic pyramid in agroecosystems, and this explains partly the decrease of biodiversity. Alternatives to manage weeds are studied to reduce negative effect of herbicides on the environment in order to preserve biodiversity. For example, weeds could be managed with granivorous species. Indeed, weed seeds are the origin of the weed community, thus seed consumption could limit weed abundance in cultivated fields. In agroecosystems, several taxa are known to be granivorous such as vertebrates (birds and rodents) and invertebrates (ground beetles). Ground beetles are considered as the main granivorous taxa in agroecosystems and are abundant in temperate agroecosystems. The main goal of this PhD was to study trophic interactions between communities, weed seed and ground beetles, with a prey-predator system in order to estimate the role of ground beetles through their seed consumption in weed seeds management. First, we established a protocol with standardize steps in order to restrain variables to weed seed species at ground beetles’ species. A similar protocol has been adapted to replicate experimentation with the same individuals to measure consumption at different weed seed densities. We then studied interactions between weed seeds and ground beetles with two research axes. We first explored interspecific variation of consumption on the same weed seeds species, Viola arvensis, by ground beetles. Body mass and ratios between mandible length and labrum width had no relation with seed consumption by ground beetles. Thus, other factors were suggested to explain consumption variation such as gut symbionts of ground beetles or preferences for specific weed seed species. Secondly, we measured consumption of 42 weed seed species by four ground beetles to identify abilities in weed seed consumption for these beetles and to explore feeding strategy according to two seed characteristics, seed mass (size) and seed lipid content. Generalism degrees are different according to ground beetles’ species and seem affected by physiological characteristics in both communities. Finally, to assess the potential in weed seed management of ground beetles we determined functional response to four ground beetles on two weed seeds species. We determined type II response for all species (male and female) tested, except for females of P.rufipes. Our results should be interpreted cautiously as, under natural conditions, generalist predators meet many alternatives prey and it could influence functional response type. We showed that there are many complex interactions between weed seed and ground beetles communities, especially due to a wide range of diversity in physiological characteristics in both communities. The potential of ground beetles to regulate seeds must be more precisely explored to evaluate their agronomic interest in weed management
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Dennis, Peter. "The predatory potential of staphylinid beetles in cereals." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328729.
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Clark, M. Sean. "Generalist predators in reduced-tillage corn : predation on armyworm, habitat preferences, and a method to estimate absolute densities /." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11102009-020213/.
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Boursault, Aline. "Caractérisation des relations trophiques entre composantes d'un agroécosystème : le cas de la prédation des graines d'adventices par les Carabidae." Thesis, Dijon, 2012. http://www.theses.fr/2012DIJOS119/document.
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L’agroécologie offre de nouvelles perspectives à l’agriculture et ainsi une voie vers une gestion alternative des adventices à travers différents mécanismes écosystémiques de régulation. La prédation des graines est l’un d’entre eux et son étude fait depuis peu l’objet de recherches visant à approfondir les connaissances relatives à ce processus. Ce travail de thèse cherche (i) à caractériser la prédation des graines d’adventices, les principaux prédateurs Carabidæ et la ressource en graines disponible à l’échelle locale dans une culture courante (blé d’hiver); (ii) à étudier précisément les profils de prédation des principaux prédateurs et les interactions entre les composantes biologiques impliquées; (iii) à introduire des éléments de réponse relatifs au potentiel de régulation des communautés d’adventices via la prédation des graines par les Carabidæ. Des approches complémentaires ont été utilisées afin de répondre à ces problématiques : un suivi à long terme de terrain, des tests de préférences en laboratoire, une simulation des taux de prédation à long terme à partir des données ponctuelles ainsi qu’une étude à grande échelle des prédateurs et du stock de graines.L’étude des variations spatio-temporelles de la prédation via un dispositif de terrain durant la période d’activité des prédateurs a mis en évidence trois pics de prédation dont un seul correspond au pic de prédateurs (avant la moisson). La ressource en graines disponible au sol est quant à elle présente majoritairement lors du premier et du dernier pic de prédation, et aucune augmentation de ressource n’a été observée après moisson. Ces dynamiques semblent stables, restant valables indépendamment de l’échelle spatiale (intra ou interchamp) et des espèces carabiques et adventices étudiées.Toutes les espèces adventices ne font pas l’objet de la même intensité de prédation, et de manière générale, les graines de petites tailles ont été préférentiellement prédatées, au champ comme en test de cafétéria au laboratoire. Cependant, les espèces carabiques semblent avoir des profils de prédation différents entre guildes trophiques, ainsi qu’au sein d’une même guilde. De ce fait, la prise en compte des préférences de consommation dans l’étude des relations prédation-prédateurs tout comme la combinaison des données prédateurs et graines disponibles permet parfois d’améliorer les corrélations, notamment pour les espèces les plus prédatées.Une simulation de la prédation annuelle suggère des pertes en graines dues à la prédation non négligeables, pouvant atteindre pour l’espèce la plus prédatée, ici Viola arvensis, jusqu’à près de 80% des graines disponibles. En parallèle, une étude à grande échelle de l’évolution du stock de graines montre une corrélation négative entre prédateurs et évolution de la banque de graines, suggérant une régulation de la banque de graines via les prédateurs carabiques.L’ensemble de ces résultats suggère que prendre en compte la diversité fonctionnelle des communautés de prédateurs et d’adventices est un point important dans la compréhension de la prédation compte tenu des préférences de consommation des prédateurs et des dynamiques temporelles des différents acteurs<br>Agroecology gives evidence of new perspectives in agriculture, and open doors for alternative weed management approaches through different regulation mechanisms. Seed predation is one of them, and the interest is growing to deepen knowledge, relative to this process. This Phd work aims (i) to describe weed seed predation, the dominant carabid predators and the available resource at a local scale in a common crop (winter wheat); (ii) to study predation profiles of main predators, and the pair-wise correlations between the biological components of the system; (iii) to bring new insights regarding potential regulation of weed communities, through seed predation by carabid beetles. Complementary approaches have been used to tackle these aspects: a long-term field study, some cafeteria tests, a simulation of annual predation rates from point-to-point estimates, as well as a large-scale field study of predators and seed resource. Study of spatio-temporal variations of predation, via field experiment during the main activity period of carabids, has shown a three-peak pattern, one of them corresponding to predators’ peak, just before harvest. Weed resource available on soil surface is high in the first and last peaks of predation, and no increase of resource has been observed after harvest. These dynamics are independent of the spatial scale (intra or inter-field) and carabid species. The different weed species do not show the same levels of predation, and, as a whole, small-seeded species are more eaten, in both lab and field conditions. However, carabids have different preferences among trophic guilds, but also within a same guild. Therefore, in order to study predation, it is essential to combine predators and seed data, as well as considering preferences of predators. A simulation of annual seed predation shows important rates of seed loss, reaching up to 80% for the most predated species, V.arvensis. A large scale study of seed bank shows a negative correlation between predators’ activity density and seed bank change, assuming that there is a seed bank regulation by carabid predators. All together, these results show that functional diversity of predators’ and weeds’ communities is a key factor in understanding predation
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Mair, Jacqueline. "The role of Pterostichus madidus and Nebria brevicollis as predators of the slug Deroceras reticulatum." Thesis, University of Newcastle Upon Tyne, 2000. http://hdl.handle.net/10443/382.
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Slugs are important pests in many agricultural crops and potential biological control agents are being studied as an alternative to molluscicide application. The role of the carabids Pterostichus madidus (Fabricius) and Nebria brevicollis (Fabricius) as predators of the slug Deroceras reticulatum (MUller) was examined in the laboratory. These generalist beetle species were only capable of killing small, healthy slugs (<0.1 ig) as they were unable to overcome the defence mucus production of larger slugs. Dead slugs were scavenged in preference to killing healthy slugs. The relatively high proportion of positive serological results from field caught carabids may reflect a high scavenging rate rather than actual predation on live slugs. Slugs are difficult prey items for generalist beetles to overcome due to their defence mucus production. Results suggest that few slugs will be consumed in the presence of alternative prey which are less difficult for beetles to overcome. Slugs which could no longer produce defence mucus were readily attacked by both beetle species. Although beetles killed few healthy slugs the presence of beetles influenced slug behaviour with slugs of all sizes foraging for shorter periods of time. Any reduction in slug activity on the soil surface would in turn lead to a reduction in seedling damage. The results suggest that the role of potential predators in pest control can only be evaluated fully with a detailed understanding of their behaviour.
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Tooley, Josephine Anne. "Weed seed predation by Carabid beetles in arable farming systems." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408983.
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Lawson, Simon A. "Studies on two predators and a parasitoid of Ips grandicollis Eichh., the five-spined engraver beetle, in South Australia /." Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09A/09al425.pdf.
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Wittaker, S. A. "The role of ladybird beetles in determining the abundance of cereal aphids." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378908.
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Armsworth, Clare Gillian. "Influence of a carabid beetle predator on the behaviour and dispersal of slug pests." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/55967/.
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It is becoming increasingly recognised that natural enemies in arable land, particularly polyphagous predators such as carabid beetles, may help to suppress populations of pests, and that appropriate management of such predators may lead to a satisfactory level of pest control. Previous work has shown that a polyphagous carabid predator, Pterostichus melanarius, is capable of affecting the spatial and temporal dynamics of slug pest populations. This project is an examination of how P. melanarius affects the survival, behaviour and dispersion of two important slug pests, Deroceras reticulatum and Arion intermedins, and how this information applies to spatial and temporal data previously obtained from the field. Deroceras reticulatum, but not Arion intermedius, elicited a variety of anti-predator behaviour in the presence of substrates previously exposed to the predator. The movements of slugs in arenas, incorporating a zone containing paper upon which the predatory beetles had previously been maintained and a control zone, were recorded at intervals. Significantly more slugs of all the size classes tested accumulated on the control half of arenas after 24 hours, with small slugs being quickest to respond. Slugs avoided paper exposed to both male and female beetles. Slugs also avoided paper exposed to another predatory carabid, Pterostichus madidus, but not to Harpalus affinis, a phytophagous carabid. Slugs did not respond to paper that had been exposed to beetles and then stored for five days prior to the test. Changes in parameters of movement of slugs when in the presence of P. melanarius chemicals were detected using a video-tracking system. These changes are consistent with a kinesis that would enable slugs to rapidly escape from areas where beetles were recently present. Despite this no changes in the rate of dispersion of D. reticulatum juveniles was detected in mini-plots previously exposed to P. melanarius. However, adult D. reticulatum reduced feeding and egg-laying and increased refuge on soil previously exposed to P. melanarius. Chemicals on the exterior of P. melanarius were isolated and two compounds were found to reduce feeding by D. reticulatum on leaf discs compared to control discs. One of these chemicals is currently being analysed using mass spectroscopy and NMR to determine it's structure and identity. It was concluded that D. reticulatum have evolved behavioural responses to chemical cues from either this generalist carabid predator in particular, or carabid beetles generally, many species of which include molluscs in their diets. During a video-tracking study of beetle movements, some evidence was found for the detection and response of beetles to slug mucus, and amputation work suggested that the palps may be important in slug detection. Previous feeding experience was found not to influence prey choice in P. melanarius during a food choice experiment, with beetles always selecting a mixed diet when offered. Analysis of spatial data showed that slug size, but not beetle sex, was important in the spatial relationship between the predator and the prey, and this agrees with results from the laboratory experiments of slug behaviour. This work has added to the evidence provided by other studies that some generalist predators can have significant effects on the dynamics of pest populations and therefore may become useful biocontrol agents for pests if effectively managed. The implications of this work in the field of predator-prey ecology and for the efficacy of P. melanarius as a biological control agent of slugs are discussed.
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Baines, Danica Darlene Sonya. "Evaluation of adult carabid beetles (Coleoptera:Carabidae) as predators of the carrot weevil, Listronotus oregonensis (Coleoptera:Curculionidae)." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63753.
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Labeyrie, Estelle. "Mate choice, predation and chemical defense in two species of alpine leaf-beetles." Neuchâtel : [s.n.], 2000. http://doc.rero.ch/lm.php?url=1000,40,4,20051027085201-VY/1_these_LabeyrieE.pdf.
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Collins, Katherine Lucy. "The effect of habitat creation for predatory arthropods on aphid populations in winter wheat." Thesis, Open University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298183.
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Myrick-Bragg, Kennesha. "Effects of Olfactory Cues on the Movement Behavior of the Predatory Beetle Calosoma wilcoxi." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4437.
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Arthropod predators often use prey and conspecific cues to make foraging decisions. Calosoma wilcoxi (Leconte) is a voracious predatory beetle that specializes on lepidopteran larvae often found in the forest canopy, including the fall cankerworm. This study tested the hypothesis that C. wilcoxi uses olfactory cues to detect prey and conspecifics. A Y-tube olfactometer was used to test attractiveness to larvae, larval frass, conspecific cues, and volatiles from herbivore-damaged white oak leaves. C. wilcoxi did not preferentially choose the treatment in any of the experiments. There was no difference in mean time spent in the treatment or control arm for any of the cues assayed. The time to choose the treatment was significantly shorter in the female conspecific experiment only. I found no evidence that C. wilcoxi uses olfaction to locate prey; however, C. wilcoxi is attracted to conspecifics. C. wilcoxi may use conspecific cues to make informed foraging decisions.
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Lundkvist, Elisabeth. "Diversity, dispersal, and interactions among diving beetles and mosquitoes in Swedish wetlands /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/tek796s.pdf.
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Costa, Arnaud. "Aggregation, dispersal and edge behavior of the bark beetle predator Thanasimus dubius (Coleoptera: Cleridae); potential use in biological control." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/dissertations/129.
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Bark beetles are major pests of pine forests in North America that can inflict considerable damage and cause severe economic loss. The checkered beetle Thanasimus dubius Fabricius (Coleoptera: Cleridae), an abundant predator in the Eastern USA and Canada, has been suggested to influence the dynamics of several bark beetles, including the economically important southern pine beetle (SPB), Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae). Because of the importance of T. dubius in pine forests, I studied several aspects of T. dubius biology including both its chemical and dispersal ecology. I first present an experiment that was conducted to improve the rearing system of T. dubius so that sufficient numbers of predators could be produced more efficiently for both behavioral and ecological studies. Improvements to the rearing method potentially could be achieved by adding a preservative to increase the shelf-life of the diet used to feed larval T. dubius thereby allowing feeding intervals to be extended. To evaluate this, I added sorbic acid, a preservative, to the larval diet at three different concentrations (0, 0.1 and 0.2%) and for two different intervals between feedings (2-3 vs. 5 days). Additionally, I measured potential deleterious effects of this preservative on predator performance (i.e., female fecundity). I then assessed the effect of this predator on SPB survival by releasing newly hatched T. dubius larvae at several densities (0, 50 100, and 200) on pine logs infested by SPB. I also studied the chemotactic response of this predator toward various volatiles such as prey pheromones or tree volatiles in a wind tunnel. I developed a method that associated upwind flight behavior and antennal behavior to quantify the relative attractiveness of each tested source of chemical. I then conducted three experiments to investigate the ability of individual T. dubius to respond to different prey olfactory signals (bark beetle pheromones) and assess their potential for learning. First, I examined individual predator preferences toward three major prey pheromones (ipsenol, ipsdienol, and frontalin) in a study that combined a mark-release-recapture experiment with a field choice test. I also measured the responses of individual wild T. dubius in a wind tunnel, which allowed the testing of a wider range of semiochemicals (frontalin, ipsenol, ipsdienol, sulcatol, and α-pinene). A final wind tunnel experiment tested the ability of naive predators to learn two prey pheromones, frontalin and ipsenol, that were presented alone or associated with a reward. In the last chapter, I quantified the dispersal of this predator and its behavior along an edge separating a pine forest from a non-suitable habitat. I analyzed T. dubius distribution and movement in the field relative to its bark beetle prey Ips grandicollis Eichhoff (Coleoptera: Curculionidae) and to the root feeder Dendroctonus valens LeConte (Coleoptera: Curculionidae). These three insects are associated with the phenomenon of red pine decline in the Great Lakes area. Thus, understanding the relative pattern of movements of these three beetles could provide considerable knowledge on the spatial and temporal progression of red pine decline by, for instance, assessing the connection between existing pockets. I estimated the dispersal quantiles for this predator relative to its bark beetle prey and determined whether dispersal behavior was relatively homogeneous (one kind of disperser) or heterogeneous (two kinds). In a second part, I sampled the abundance of T. dubius, I. grandicollis, and D. valens along transects set between a matrix area constituted by a clearing and a habitat zone composed of red pine forest. I further developed a diffusion model, including a constant k (corresponds to the ratio of densities along the edge), that permits characterization of beetle behavior around the boundary. Studies developed in the present dissertation, therefore, investigated several aspects of T. dubius ecology: predation on SPB, ability to respond to an olfactory signal, and dispersal traits. I first showed that augmentation with larval T. dubius can successfully reduce the SPB ratio of increase in infested pine logs. I also developed a system of rearing T. dubius that was more efficient and could allow larger numbers of predators to be produced. Sorbic acid did not reduce adult lifetime or size but did affect female fecundity (20 - 40% reduction). Increasing feeding time interval to 5 days (instead of 2-3 days) improved the efficiency of the system, even when sorbic acid was not added in the diet. Wind tunnel experiments present a methodology that could enable future quantification of the relative attractiveness of various semiochemical treatments. I identified a particular antennal behavior, which I called "stand up antennal" that was typically produced when the insect was attracted to a semiochemical. The choice tests in the field and the wind tunnel experiment using wild adults both showed that T. dubius individuals are generalists that are flexible in their response to a broad range of semiochemical signals (frontalin, ipsenol, ipsdienol, sulcatol, and α-pinene). I demonstrate that naive predators are more attracted toward ipsenol after having experienced conditioning with this kairomone via a reward. Finally, experiments on dispersal and edge behavior revealed that T. dubius and one of its common prey, the bark beetle I. grandicollis, exhibit a different pattern of movement within red pine stands and surrounding habitats. First, adult T. dubius can disperse substantially further (50% dispersed beyond 1.54 km) than I. grandicollis adults (50% dispersed beyond 0.13 km). Second, T. dubius was highly affected by the presence of an edge, showing a step-like pattern with very predators caught in unsuitable areas. Conversely, the behavior of I. grandicollis was less limited by such a boundary. As with T. dubius, the root colonizer D. valens showed a strong edge behavior that was characterized by avoiding matrix zones.
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Almady, Saad. "Technical feasibility of the mechanical release of predator insects to control the Colorado potato beetle, Leptinotarsa decemlineata (Say)." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30284/30284.pdf.
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Le doryphore de la pomme de terre (DPT), Leptinootarsa decemlineata (Say) (Coleoptera: Chrysomelidae) est l’insecte ravageur qui cause le plus de dommage aux plants de pommes de terre, de tomate et d’aubergine en se nourrissant de leur feuillage. Le DPT est devenu un phénomène inquiétant vu sa présence dans presque 16 millions de km² répartis à travers l’Amérique du Nord, l’Europe et l’Asie et il continue par sa grande capacité de se propager. Actuellement, les insecticides chimiques représentent le moyen le plus efficace pour lutter contre le DPT. Malheureusement, l’utilisation excessive des produits chimiques pour lutter contre le DPT devient inefficace après quelques années puisque cet insecte nuisible réussit à développer une résistance envers ces produits. Aussi, l’utilisation excessive et incontrôlée des insecticides chimiques est coûteuse pour les producteurs de pommes de terre et pourrait résulter en de sérieux problèmes environnementaux et de santé humaine. Compte tenu de ce qui précède, les chercheurs scientifiques ont redoublé d’efforts pour trouver des alternatives intéressantes aux produits chimiques afin de lutter contre le DPT. Une des alternatives consiste à utiliser le contrôle biologique en procédant à un lâcher massif d’ennemis naturels du DPT. Cette alternative qui ne fait recours à aucun produit chimique est très avantageuse puisqu’elle permet de produire des produits biologiques tout en préservant l’environnement. L’efficacité de cette alternative à contrôler le DPT a été prouvée à petite échelle. Toutefois, le lâcher manuel des insectes prédateurs à grande échelle est inconcevable. Pour remédier à ce problème, quelques récents travaux de recherche ont mis l’emphase sur le lâcher mécanique des prédateurs pour lutter contre les insectes nuisibles. L’objectif de ce travail de recherche était de tester un distributeur mécanique de larves de deuxième, troisième et quatrième stades de Podisus maculiventris dans un champ de pommes de terre. Les résultats obtenus ont démontré que le prototype de distribution mécanique est efficace en ce qui a trait au lâcher de prédateurs dans les parcelles de pommes de terre. Aussi, le contrôle du DPT dans les parcelles de lâcher mécanique est aussi efficace que celui dans les parcelles de lâcher manuel et ce par comparaison aux parcelles témoins sans aucun contrôle.<br>The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) is a pest insect that can cause real damage to potato, tomato, and eggplant crops by consuming their leaves if left uncontrolled. The CPB is becoming an alarming phenomenon because of its presence in about 16 million km² spread across North America, Europe, and Asia, and it is still spreading. Currently, chemical insecticides are the most effective mean to control the CPB. Unfortunately, the exclusive use of chemicals to control the CPB becomes ineffective after few years because this pest insect succeeds to develop resistance to such chemicals. Also, excessive and uncontrolled use of chemical insecticides is costly for potato growers and could lead to serious human health and environmental problems. Therefore, scientists have been trying to find interesting alternatives to control the CPB. One of these alternatives consists of using the biological control by massive release of natural enemies of the CPB. This chemical free alternative has several significant advantages as it allows producing organic food while preserving the environment. The effectiveness of this alternative in controlling CPB populations has been proven at small scale. However, hand release of predator insects at large scale is unconceivable. To remedy to this problem, some recent studies carried out in the last few years have focused on the mechanical release of predators to control pest insects. The objective of this research study was to test a mechanical distributor of second, third, and forth-instar nymphs of Podisus maculiventris in a potato field. Obtained results showed that the mechanical release system is efficient in releasing predators in potato plots. Also, the control of CPB in the mechanical release plots is as efficient as that in the manual release plots compared the check plots with no control.
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Esquivel, Palma Carlos Josue. "TOXICOLOGICAL INTERACTIONS BETWEEN THIAMETHOXAM, APHIDS, AND PREDATORY NATURAL ENEMIES." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574435608424832.
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Finlayson, Christy J. L. "Comparisons of Native and Non-Native Lady Beetles: Habitat Distribution and Interactions with Prey and Competitors." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/FinlaysonCJL2009.pdf.
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Dalin, Peter. "Food-web interactions and population variability of leaf beetles in managed and natural willow stands /." Uppsala : Dept. of Entomology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s303.pdf.
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Kajita, Yukie. "Reproductive Tactics of Aphidophagous Lady Beetles: Comparison of a Native Species and an Invasive Species that is Displacing It." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/137.
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Coccinella septempunctata L. (Coleoptera: Coccinellidae) has been introduced to North America in recent decades, raising concerns of adverse impacts on native lady beetles, including the congeneric C. transversoguttata richardsoni (Brown). The central focus of my dissertation is to understand the importance of reproduction, in particular, in promoting invasion of C. septempunctata and its replacement of native lady beetles in alfalfa fields of western North America. Studies were conducted to compare reproductive tactics of the invasive C. septempunctata and the native C. transversoguttata, by addressing: 1) maximum rate of reproduction of overwintered lady beetles, 2) population dynamics of the invasive and native lady beetles and their aphid prey, and seasonal reproductive patterns, over a 3-year period (2004'2006) in alfalfa fields, 3) reproductive tactics and plasticity in response to various prey availabilities, and 4) ovarian dynamics and observation of oosorption in response to prey removal. The invasive C. septempunctata gained a reproductive advantage over native, North American lady beetles from its larger body size when feeding on abundant prey. The invasive species gained additional advantage by its allocation of prey to larger numbers of relatively small eggs. In alfalfa fields, females of C. septempunctata reproduced more readily and laid more eggs than females of C. transversoguttata even at low prey density. C. septempunctata females collected from the field were also more successful in approaching their maximum body weights and reproduction, as observed under ideal conditions, than were females of native C. transversoguttata. In the laboratory, C. septempunctata females produced larger numbers of relatively small eggs, and they maintained their body weights even as they were producing eggs at low rates when aphids were provided in limited numbers. More immediate adjustment of reproductive effort with prey removal, and higher recovery of reproductive rate when prey again became available, were observed in C. septempunctata, compared with C. transcersoguttata. These reproductive abilities of C. septempucntata may contribute to its invasion success and dominance in alfalfa fields. Further studies are needed to determine why females of C. septempunctata are in better physiological condition than are females of C. transversoguttata in spring alfalfa fields.
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Östman, Örjan. "Landscape and farm management influence generalist predators : effects on condition, abundance, and biological control /." Uppsala : Swedish University of Agricultural Sciences, 2002. http://diss-epsilon.slu.se/archive/00000207/.
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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2002.<br>Thesis documentation sheet inserted. Appendix reprints five published papers and manuscripts, three co-authored with others. Includes bibliographical references. Also available electronically via World Wide Web in PDF format; online version lacks appendix.
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Korol, Jerome John. "A simulation of predation by non-game birds on the mountain pine beetle (Dendroctonus ponderosae Hopkins)." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25882.
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Available information on bird-lodgepole pine, bird-mountain pine beetle, and mountain pine beetle-lodgepole pine interactions was reviewed. A computer model was constructed for the purpose of simulating variations in these interactions. Three lodgepole pine stand structures and three sets of bird responses to changes in beetle density were simulated. It was determined that birds may be able to suppress beetle population growth and reduce maximum beetle density under 'typical' stand conditions, but could only prevent an epidemic when unrealistically high bird densities were assumed. Increasing base-line bird densities to levels which were realistically obtainable had effects similar to those obtained when predator efficiency was increased. No amount of avian predation could prevent a massive epidemic from occurring when stand conditions were such that beetle productivity was optimized. A mountain pine beetle epidemic, as well as bird functional and numerical responses, did not occur when a stand structure representing a preventive thinning was simulated. Preventive silvicultural methods such as thinning or reduction of rotation age, combined with practices such as retention of wildlife trees on clearcut sites in order to increase non-game bird densities, could help prevent endemic beetle populations from reaching epidemic levels.<br>Forestry, Faculty of<br>Graduate
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Dieterich, Mabin Molly E. "Effects of conservation biological control practices on predatory arthropod assemblages and molecular identification of cucumber beetle biological control agents." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492531428052099.
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Smith, Chelsea A. "Testing an Interference Competition Hypothesis to Explain the Decline of the Convergent Lady Beetle, Hippodamia convergens (Coleoptera: Coccinellidae), in Ohio." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339527346.
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Jubb, Carrie Sue. "Evaluation of the establishment of predatory beetle, Laricobius nigrinus (Coleoptera: Derodontidae) in Virginia, and assessment of its impact on hemlock woolly adelgid (Hemiptera: Adelgidae) at release sites in the eastern U.S." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/92617.
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The predatory beetle, Laricobius nigrinus Fender (Coleoptera: Derodontidae), has been released in the eastern U.S. since 2003 for the management of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae). The establishment of L. nigrinus at release sites in Virginia was assessed in 2017 and 2018. Sampling was performed in both years to determine presence or absence L. nigrinus. Stand level HWA densities, tree health, predator-prey ratios, and Laricobius spp. identifications were also assessed at each site. Laricobius nigrinus established at 82% of sites and was the primary species recovered. HWA densities appeared to decline, and tree health appeared to improve in year two. Predator-prey ratios were lower than those indicated in the native range, however much is left to be understood about the dynamics of this system in its introduced range. A separate two-year study to assess the impact of L. nigrinus on HWA was initiated in 2014 (Phase One) at nine sites in the eastern U.S. Significant predation of HWA sistens ovisacs was demonstrated during this period, therefore, it was continued from 2016-2018 (Phase Two) to provide longer-term evaluations. Predator exclusion cages were used to monitor predator and prey populations. In Phase Two of the study, mean ovisac disturbance rates on no-cage branches were significantly greater than caged branches and were as high as 80%, suggesting that L. nigrinus can have a significant impact on the sistens generation. Microsatellite analysis of Laricobius larvae indicated that L. nigrinus was the primary species recovered at study sites.<br>Master of Science in Life Sciences<br>Hemlock woolly adelgid (HWA), an invasive insect native to Asia and western North America, is a significant threat to two native hemlock species in the eastern U.S. Since 2003, a predatory beetle, Laricobius nigrinus, has been released for management of HWA. In biological control programs such as this one, it is important to evaluate the ability of predators to establish and impact prey in areas where they are introduced, as this helps guide future management decisions. As such, a study was conducted to examine the ability of L. nigrinus to establish after being released at 26 locations in Virginia. In those investigations we found that L. nigrinus established at 82% of the sites. Although promising, longer-term studies are needed to understand if the predation of HWA by L. nigrinus helps improve the health of our native hemlocks. A separate two-phase study was carried out from 2014-2016 and 2016-2018 evaluating the impact of L. nigrinus on HWA at nine release sites in the eastern U.S. In Phase Two reported here, cages were used to exclude L. nigrinus on some HWA infested branches while on others, no cage was applied to allow free access to HWA. Comparisons between branches were made to determine the level of predation by L. nigrinus. These studies showed a significant impact by L. nigrinus on the winter generation of HWA with as many as 80% of those insects being attacked on study branches which indicates that this species has potential as an effective predator.
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Diehl, Jason K. "Biological control of purple loosestrife, Lythrum salicaria L. (Lythraceae) with Galerucella spp. (Coleoptera: chrysomelidae), dispersal, population change, overwintering ability and predation of the beetles, and impact on the plant in southern Manitoba wetland release sites." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ41691.pdf.
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Bertrand, Colette. "L'hétérogénéité spatiale et temporelle des paysages agricoles influence les auxiliaires généralistes des cultures et le potentiel de contrôle biologique des ravageurs." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S161/document.
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Les carabes et les araignées sont des auxiliaires généralistes susceptibles d'exercer un contrôle efficace des ravageurs des cultures. La structure et composition de leurs communautés, ainsi que l'efficacité du contrôle biologique, dépendent de l'hétérogénéité des paysages, et en particulier de la présence d'habitats semi-naturels. Mais le rôle de la mosaïque agricole, susceptible de présenter une forte hétérogénéité dans l'espace et dans le temps, reste aujourd'hui peu connu. L'objectif de ce travail a été d'évaluer les effets de l'hétérogénéité spatiale et temporelle des paysages agricoles sur des auxiliaires généralistes et sur le potentiel de contrôle biologique. Nous avons échantillonné les communautés de carabes et d'araignées dans des parcelles de céréales, et estimé le potentiel de prédation par des pucerons sentinelles collés sur des cartes de prédation. Nous avons caractérisé l'hétérogénéité spatiale des paysages autour des parcelles de céréales par le pourcentage d'éléments boisés et la longueur du réseau de haies, la taille moyenne des parcelles agricoles, et la diversité des cultures. Nous avons également mis au point quatre nouvelles métriques qui synthétisent différents aspects de l'hétérogénéité temporelle interannuelle des surfaces cultivées. Nos résultats montrent qu'au printemps les araignées sont plus abondantes dans les parcelles de céréales situées dans des paysages composés de petites parcelles. Au début de l'été, ces paysages favorisent également les taux de prédation de pucerons mesurés par les cartes de prédation, et l'abondance des carabes qui se reproduisent au printemps et qui hivernent en tant qu'adultes dans des habitats semi-naturels. Les carabes qui hivernent dans le sol des parcelles au stade larvaire et se reproduisent à l'automne sont quant à eux favorisés par la diversité des cultures dans le paysage. Nos résultats montrent enfin que l'hétérogénéité temporelle de la mosaïque agricole - caractérisée par les changements de la diversité de cultures au cours des cinq dernières années - favorise elle aussi certaines espèces de carabes communément rencontrées dans les parcelles agricoles (Poecilus cupreus ou Pterostichus melanarius) et susceptibles de jouer un rôle important en tant qu'auxiliaires. Ces résultats mettent en avant le rôle complémentaire des bordures de champs non cultivées et de la mosaïque des cultures pour différents groupes d'auxiliaires, et soulignent l'importance de prendre en compte l'hétérogénéité spatiale et temporelle des surfaces cultivées dans l'étude de la biodiversité des paysages agricoles. Dans le contexte de réduction des produits phytosanitaires, nos résultats suggèrent que des paysages présentant une diversité de cultures importante variable dans le temps, et des petites parcelles qui favorisent l'intrication entre les habitats semi-naturels et les cultures, sont susceptibles de favoriser les auxiliaires généralistes ainsi que le potentiel de contrôle biologique des ravageurs<br>In the context of reducing pesticide use, the potential role of some arthropod groups as pest natural enemies provides them an ecological and economic interest. In particular, ground beetles and spiders are generalist predators likely to be effective biocontrol agents. Previous studies have shown that the structure and composition of their communities, as well as the effectiveness of biological control, are influenced by landscape heterogeneity, and in particular by the presence of semi-natural habitats. However, the role of the crop mosaic, which can be highly heterogeneous in space and time, have been little considered. The main objective of our study was to determine the influences of spatial and temporal heterogeneity of agricultural landscapes on generalist natural enemies and the potential for biological pest control. We sampled carabid and spider communities in winter cereal fields, and estimated biological control potential using sentinel aphids glued on predation cards. We characterized the spatial heterogeneity of the landscapes around each cereal field by 1) the amount of wooded habitats and the length of the hedgerow network, 2) the average size of the agricultural fields, and 3) crop diversity. We also proposed four new metrics that synthesize different aspects of the multi-year temporal heterogeneity of cropped areas. Our results show that in spring, landscapes characterized by small fields, and therefore by a high density of non-cropped field margins, promote spiders abundance in cereal fields. In early summer, landscapes with small fields also promote aphid predation rates and the abundance of carabid spring breeders, which overwinter as adults in semi-natural habitats. Crop diversity promotes the abundance of carabids overwintering in soils of arable fields and breeding in autumn. Our results also show that the temporal heterogeneity of the crop mosaic - characterized among other things by the changes in crop diversity over a five year period - benefits some carabid species commonly found in agricultural landscapes (such as Poecilus cupreus and Pterostichus melanarius) which are likely to play an important role as pest natural enemies. These results highlight the complementary role of the crop mosaic and the non-cropped field borders for generalist natural enemies, and show the importance of taking into account the spatial and temporal heterogeneity of the cultivated area in further ecological studies on biodiversity in agricultural landscapes. In the context of reducing pesticide use, our results suggest that landscapes with 1) a high crop diversity that change over time, and 2) small fields that promote the interspersion between crops and semi-natural habitats, are likely to promote generalist natural enemies and biological pest control
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Charalabidis, Alice. "Effect of inter-individual variabilities and intraguild interferences on the foraging stratégies of seed-eating carabid species." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK035/document.
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Faire un choix n’est pas juste un évènement spontané. La recherche d’une ressource alimentaire, par exemple, implique un investissement temporel et est donc en conflit avec d’autres activités essentielles telles que la vigilance pour les prédateurs. Ainsi être sélectif augmente le risque de se faire attaquer par un prédateur. Par ailleurs, être sélectif implique aussi de rejeter beaucoup de potentielles options avant de finalement en accepter une et donc accepter une perte non négligeable d’opportunités en présence de potentiels compétiteurs. Pour ces raisons, une réduction du niveau de sélectivité est attendue chez un individu exposé à une situation de forte compétition ou à un fort risque de prédation. Les carabes évoluent au sein de communautés composées, pour la plupart, d’un nombre important de potentiels compétiteurs et prédateurs. Les connaissances actuelles en écologie comportementale et en écologie prévoient que le comportement d’approvisionnement alimentaire des coléoptères carabiques devrait varier en fonction des niveaux de risques de compétition et de prédation qu’ils rencontrent et donc de la composition des communautés dans lesquelles ils se trouvent. Dans cette thèse, nous avons mesuré les changements de sélectivité alimentaire de deux espèces de carabes en présence de signaux de prédateurs ou de compétiteurs. A l’aide d’expériences de laboratoire effectuées à différentes échelles spatio-temporelle, nous avons réussi à montrer que la sélectivité alimentaire d’un carabe granivore Harpalus affinis peut varier en fonction du contexte dans lequel il cherche sa nourriture et être diminuée en présence de prédateurs. Par ailleurs le sexe des individus, l’espèce de graine qui leur est proposée et l’intensité du risque auquel ils sont confrontés semblent aussi avoir un effet sur la variation de sélectivité des individus. Aucun lien n’a cependant été trouvé entre le statut immunitaire ou la personnalité des individus et leur niveau de sélectivité alimentaire. Testé dans des conditions similaires, le carabe omnivore Poecilus cupreus, quant à lui, ne fait pas varier sa sélectivité pour les ressources testées. S’ils sont extrapolables ces résultats pourraient servir à expliquer la grande variabilité des taux de prédation de graines au champ par les carabes rapportés dans les différentes études. Ces résultats pourraient permettre aussi d’expliquer la difficulté d’extrapolation existante entre les taux de prédation de graines mesurés en laboratoire et les résultats obtenus au champ. Globalement, cette thèse confirme qu’une meilleure compréhension du processus de prise de décision chez les carabes est essentielle pour évaluer leur efficacité en tant que potentiels auxiliaires de cultures<br>Making a choice requires, implicitly, an investment of time in one behaviour at the expense of an investment in another. Being choosy would increase the risk of losing many food item opportunities to competitors, and is directly in conflict with other essential tasks such as predator avoidance. Individuals are thus expected to adjust their level of choosiness in response to the competition and predation context. The available behavioural ecological theory and the empirical ecology of carabids would suggest that competition and predation interference induces changes in the foraging behaviour of carabid individuals. Carabids typically operate within communities in which competition and predatory interference interactions occur and are ever present; there are high levels of intraguild interference. A better understanding of how risks of these two interference interactions modify individual decision making for prey would therefore help to improve the biocontrol of weeds by communities of carabids. This thesis focused on how changes in level of choosiness occur when individual carabids forage under intraguild interference. Using laboratory experiments, done at different spatio-temporal scales, we demonstrate that the decision-making processes of foraging carabids might differ between contexts, between species and between individuals. Our focal species, the granivore Harpalus affinis, was found to reduce its level of choosiness while foraging under intraguild interference. In doing so H. affinis individuals increased their overall rate of seed acceptance. This change in choosiness was dependant on the intensity of the risk, the seed species offered in test and the sex of individuals. We found no link between individual levels of choosiness and either immunity or personality traits. When tested under similar conditions, individuals of the omnivorous carabid Poecilus cupreus did not change their level of choosiness for seeds. These findings would help explain the high variability in seed predation rates observed between studies conducted in-field, and the differences observed between laboratory studies and fields measurements in carabids. Globally, this thesis has confirmed that a deeper understanding of the decision making process of carabids seed-eating species is requires to evaluate their choice of prey and assess their relevance as biological control agents in the wild
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Watts, Corinne Hannah. "Invertebrate community reassembly and altered ecosystem process rates following experimental habitat restoration in a mined peat bog in New Zealand." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1481.
Full textAbstract:
I investigated the effects ofhabitat loss and subsequent restoration on invertebrate community structure and ecosystem functioning in a mined peat bog in the North Island, New Zealand. In an experimental trial, the impact of peat bog habitat loss and isolation on the invertebrate community associated with Sporadanthus ferrugineus (Restionaceae) was investigated. Potted S. ferrugineus plants were exposed to invertebrates at various distances up to 800 m from an intact habitat (the presumed source population) over 18 weeks. Invertebrates rapidly colonised the experimental plants, with all major Orders and trophic groups present on Sc ferrugineus within 6 weeks. However. with increasing distance away from the undisturbed habitat, there was a significant decrease in total richness and abundance of invertebrates associated with the potted plants. Additional tests showed that even a moderate degree of isolation (i.e. greater than 400 m) from the intact habitat caused an almost complete failure of 'Batrachedra' sp. to colonise its host plant, at least in the short-term, The density of eggs and larvae, and the average larval size of 'Batrachedra' sp. (Lepidoptera: Coleophoridae) colonising Si ferrugineus plants, as well as the proportion of Si ferrugineus stems damaged by 'Batrachedra' sp. herbivory, all decreased logarithmically with increasing distance from the intact habitat. Surprisingly, though, the rate of recovery of the insect-plant interaction following experimental habitat restoration was remarkably rapid (i.e. between 3Y2 and 6 years). After just 6 years there was no significant difference in insect-plant interactions between the intact peat bog sites and any of the experimentally restored sites up to 800 m away. These results suggest that the degree of isolation from undisturbed habitat has a major impact on the rate and patterns of restoration recovery in the invertebrate community and that some insect-plant interactions can recover rapidly from habitat loss with restoration management. Restoration of mined peat bogs in northern New Zealand is initiated by establishing a native vegetation cover to minimize further peat degradation. The effects of various restoration techniques on litter decomposition, microbial community activity and beetle community composition were investigated within an experimental trial, These treatments included translocation ofpeat bog habitat (direct transfer of islands), milled peat islands with no seed and milled peat islands with seed, and were compared with an unrestored mined site and an undisturbed peat bog. In all the response variables measured, the undisturbed peat bog sites had significantly higher decomposition rates and microbial respiration rates, and significantly higher abundance and species richness of beetles than any of the restoration treatments. Inaddition, the technique used to restore mined peatlands had a significant effect on the beetle community composition and litter decomposition processes. Despite a rapid initial change in the beetle community following habitat translocation, the direct transfer islands were still the most similar in beetle species composition to the undisturbed peat bog. Microbial activity and decomposition rates were higher in the direct transfer and mined peat surface after 6 months. However, even after 12 months, decomposition rates in the restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. The results suggest that beetle community structure and ecosystem processes such as decomposition and microbial activity rates may be able to recover faster with certain restoration techniques, such as direct transfer of intact habitat islands. Subsequently, I examined long-term beetle community reassembly on islands that had been restored by creating raised areas ofprocessed peat with the addition of Leptospermum scoparium seed. Monitoring of different-aged restored islands representing the full range of restoration ages (up to 6 years) available at the peat mine, indicated that as the peat islands became older and the vegetation structure became more complex, the abundance, species richness and composition of the beetle community became increasingly similar to the community in the undisturbed peat bog. Despite this, distinct differences between the intact peat bog and older restored peat islands still persisted, even after 6 years, particularly at an individual species level. However, it is predicted that within 12 years the restored peat islands will share 100% ofbeetle species in common with the undisturbed peat bog. Taken together, these results indicate that restoration is effective in initiating the recovery of beetle assemblages and ecosystem processes (such as litter decomposition and microbial community activity) in cut-over peat bogs. However, it is estimated to take at least 12 years before pre-mining communities and functions are attained, and ongoing monitoring to develop an understanding of the longer-term dynamics of such ecosystems and processes is clearly required.
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Slade, Eleanor M. "The effects of tropical forest management on biodiversity and ecosystem functioning." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:d4689410-3c13-4e92-9f35-e4abe0d8e0ac.
Full textAbstract:
The Effects of Tropical Forest Management on Biodiversity and Ecosystem Functioning Eleanor M. Slade 1. Between 35 % and 50 % of all closed-canopy tropical forest has been lost, and the rate of deforestation continues to increase throughout the tropics. Despite a wealth of literature on the effects of tropical forest disturbance on the diversity and composition of a variety of taxa, there is still no clear consensus on the value of disturbed forests for biodiversity. 2. If forest management practises are to be sustainable in the long-term they should maintain both biodiversity and ecosystem functioning (the interactions and processes of the ecosystem), as well as a timber harvest. However, few studies have investigated the extent to which ecosystem functioning is reduced in logged forests. The effects of different logging intensities on a variety of taxa, and the ecosystem processes with which they are associated, were assessed in the Danum Valley Conservation Area in Sabah (Malaysian Borneo). 3. Even under high logging intensities, the forests of Sabah appear to have been managed in a way that maintains timber yields in the short-term. However, other aspects of forest structure had been affected, which could have important consequences ecologically, and for the long-term sustainability of timber harvests. 4. Combining field studies with manipulative experiments allows assessment of the impacts of species changes associated with habitat modification on measures of ecosystem functioning. Dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) functional group richness and composition were manipulated in a series of field experiments. Certain functional groups and species were found to have a greater impact on ecosystem functioning than others; nevertheless a full complement of species was needed to maintain full ecosystem functioning. 5. Dung beetles appeared to be relatively robust to changes in forest structure associated with selective logging, but species richness was reduced with high-intensity logging. There was a corresponding decrease in ecosystem functioning (dung and seed removal) with a decrease in species richness, and a decrease in the biomass of large nocturnal tunnellers, suggesting that although some species are dominant, rare species are also needed to preserve full ecosystem functioning. 6. A complex interaction between birds and ants resulted in reduced herbivory of seedlings of the important timber tree, Parashorea malaanonan, in some instances. However, this interaction was not affected by either selective or high intensity logging. Seedfall of P. malaanonan, was reduced in logged forest compared to primary forest. Despite insect seed predation being higher in primary forest, there was still successful recruitment during a non-mast year. Parasitism of insect-predated seeds was found to be inversely density dependent, and was higher in logged forest where seed predation was lower. 7. The results of this thesis suggest that the forests of Sabah appear to be being logged under a management system that is compatible with sustainable timber management, but not necessarily sustainable forest management. Low intensity selective logging seems to preserve much of the original forest structure, biodiversity and ecosystem functioning compared to logging at higher intensities. However, ecosystem processes were variable in their response to logging, suggesting that management decisions should be based on the consideration of multiple taxa and processes.
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Pevere, Ines. "Effects of agricultural management and landscape on farmland biodiversity and associated ecosystem services." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424358.
Full textAbstract:
The next few decades will witness a rapidly increasing demand for agricultural products. By 2050 current food demand will be doubled by world population and socio-economic growth (FAO 2015). The expanding bio-based economy will increase the demand for agricultural products. Urban development will increasingly compete with agriculture for land use. The growing demand for agricultural products needs to be met largely through intensification (produce more from the same land surface) because there is little scope for an increase in agricultural area without doing irreparable damage to vital natural ecosystems. The steady increases in agricultural productivity per unit area seen through the latter part of the 20th century have now plateaued with little opportunity for further increases in efficiency through conventional methods. The dependency of conventional agriculture and food supply on non-renewable resources (e.g. fossil fuels, phosphate) makes it unsustainable in the long run.
Eco-functional intensification has been proposed as a promising solution (Niggli et al. 2008). Eco-functional intensification is the optimization of all provisioning, regulating and supporting ecosystem services in the agricultural production process (modified after Niggli et al. 2008). As such it advocates to maintain or enhance agricultural production through the promotion of biodiversity and associated ecosystem services. However, the implementation of ecological intensification into crop production systems is knowledge-intensive and it requires a comprehensive understanding of the relationships among multiple ecosystems services.
The aim of this thesis was to investigate how landscape structure (semi-natural habitats) and land-use (on-farm management) interact in the provisioning of some ecosystem services, that is pollination service and biological control. We explored the effects of field boundary quality, at local scale, on pollination service and pollinators community, assessing the quality of field boundaries, e.g. tree diversity, tree structural heterogeneity. Furthermore we assessed the relationship between farm management, semi-natural habitats and biological control then the combined effect of tillage management and urbanization on ground beetle communities (Coleoptera: Carabidae).
In chapter 2 we evaluated the potential interactions between pollination services and quality of semi-natural landscape elements. We tested whether abundance and richness of plant species at local scale can enhances richness and abundance of pollinators.
In chapter 3 we explored how local management practices, fertiliser and insecticide inputs and management for enhanced SOC, combined with land use at the landscape (1 km diameter circle) determined the crop yield, biological pest control, and abundance of predators. This experimental design allowed us to test for general interactive effects of management for ecosystem services and of efficiency of external inputs to crop yields.
In chapter 4 we explored the potential interactions between management intensity, landscape complexity and predators community. In a field experiment we tested the combined effect of tillage management (conventional vs. conservation tillage) and urbanization on ground beetle communities (Coleoptera: Carabidae).
Our study stresses the importance of considering both local management and landscape composition when planning strategies to support farmland biodiversity. These principles are taken up by the EU agricultural policy that through the mediation of the member states and their regions promotes the introduction of environmentally friendly farming systems, such as minimum tillage or no tillage (MT, NT) in order to increase the organic carbon into the soil and the related environmental benefits, such as conservation of nutrient cycling, species diversity and productivity.<br>I prossimi decenni saranno testimoni di un rapido aumento della domanda di prodotti agricoli. Entro il 2050 l’attuale domanda alimentare sarà raddoppiata a seguito della crescita della popolazione mondiale e della crescita socio-economica (FAO 2015). Lo sviluppo urbano sarà sempre più in concorrenza con l'agricoltura per l'uso del suolo. Si rende quindi necessario soddisfare la maggior parte della crescente domanda di prodotti agricoli attraverso l'intensificazione colturale (ossia produrre di più sulla stessa superficie agricola investita) poiché non vi è sufficiente spazio per incrementare la superficie agricola senza causare danni irreparabili agli ecosistemi naturali vitali. Il costante aumento della produttività agricola per unità di superficie, a cui si è assistito nell'ultima parte del 20° secolo si è ormai stabilizzata, con scarse possibilità di ulteriori aumenti di efficienza attraverso metodi convenzionali. La dipendenza dell'agricoltura convenzionale e dell’approvvigionamento alimentare sulle risorse non rinnovabili (ad esempio i combustibili fossili, fosfato) la rende insostenibile nel lungo periodo.
L ‘intensificazione eco-funzionale è stata proposta come una soluzione promettente (Niggli et al. 2008). Per Intensificazione Eco-funzionale si intende l'ottimizzazione dell’approvvigionamento, della regolazione e del mantenimento dei servizi ecosistemici nel processo di produzione agricola (Niggli et al. 2008). Come tale, promuove il mantenimento o la crescita della produzione agricola sostenendo la biodiversità e i connessi servizi ecosistemici. Tuttavia, l'implementazione della intensificazione ecologica nei sistemi di produzione delle colture agrarie specifiche conoscenze oltre che una comprensione globale delle relazioni tra i diversi servizi ecosistemici.
Lo scopo di questa tesi è stato quello di studiare come la struttura del paesaggio (habitat seminaturali) e l’uso del suolo (gestione in azienda) interagiscono nell’approvvigionamento di alcuni servizi ecosistemici, quali sono il servizio di impollinazione e il controllo biologico. Abbiamo indagato gli effetti del tipo di margine del campo coltivato, a scala locale, sul servizio di impollinazione e sulla comunità degli impollinatori, valutando le caratteristiche delle siepi presenti lungo i campi coltivati, ad esempio, la densità degli alberi, l’eterogeneità in termini di specie e di struttura. Inoltre, abbiamo indagato la relazione tra le pratiche gestionali agricole, gli habitat semi-naturali e il controllo biologico delle colture nonché l'effetto combinato dei tipi di lavorazione del suolo e del grado di urbanizzazione presente sulle comunità dei coleotteri Carabidi. (Coleoptera: Carabidae).
Nel capitolo 2 sono state valutate le potenziali interazioni tra impollinazione e la qualità degli elementi del paesaggio semi-naturale. Abbiamo testato se l'abbondanza e la ricchezza di specie vegetali, a scala locale, possono incentivare la ricchezza e l'abbondanza di impollinatori.
Nel capitolo 3 abbiamo esplorato come le pratiche locali di gestione agricola delle colture, (fertilizzanti e di insetticidi, pratiche colturali che favoriscono una maggiore SOC) in combinazione con il paesaggio influiscono sulla resa delle colture, sul controllo biologico dei parassiti e sull'abbondanza dei predatori. Questo modello sperimentale ha permesso di testare le generali conseguenze interattive, dovute ad una diversa gestione colturale, tra i servizi ecosistemici e il rendimento degli input esterni sui raccolti.
Nel capitolo 4 abbiamo esplorato le possibili interazioni tra intensità di gestione delle colture agrarie, la complessità del paesaggio e la comunità dei predatori. Attraverso un esperimento in campo abbiamo testato l'effetto combinato della gestione dell’aratura (lavorazione convenzionale rispetto a lavorazione conservativa) e della urbanizzazione sulle comunità di coleotteri Carabidi (Coleoptera: Carabidae).
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Meurisse, Nicolas. "Chemical ecology of rhizophagus grandis (Coleoptera: Monotomidae) and its application to the biological control of dendroctonus micans (Coleoptera: Scolytinae)." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210567.
Full textAbstract:
The Eurasian spruce bark beetle Dendroctonus micans is a major pest of spruce which is expanding its range in France, Turkey, England and Wales. Its monospecific predator Rhizophagus grandis has followed naturally the bark beetle into most areas and, since the 1960s, has also been mass-produced and successfully released within newly infested locations. <p>In this scope, the development of an effective trapping method would be very useful to assess the bark-beetle presence at previously uninfested sites, or predator establishment after release or natural spread. We demonstrated the efficiency of oxygenated monoterpenes-baited kairomone traps to monitor R. grandis in various epidemiological conditions, including areas localized behind or at the limit of the pest’s distribution, or in areas where artificial releases were performed. Because the predator is strictly species-specific, another exciting possibility offered by the kairomone trapping is the indirect monitoring of the pest itself in areas of unknown status (e.g. areas under colonization, or considered as at risk at medium- term).<p>R. grandis is also considered as one of the most valuable natural enemies to strike aggressive North-American Dendroctonus species. In this respect, R. grandis has been recently applied in a neo-classical biological program against the red turpentine beetle D. valens, which invaded China from North America in the late 1990’s. In laboratory tests conducted on pine logs in the laboratory, or on living pine trees in the field, we demonstrated that R. grandis adults can successfully enter and reproduce into D. valens galleries. <p>In Europe, R. grandis is the only species regularly found in the brood systems of D. micans, where adults and larvae attack the gregarious larvae of their prey. In such enclosed systems, R. grandis’ functional response is therefore influenced by various interrelated components, such as the prey density, the predator density, or the prey distribution. Measuring the predator’s success in terms of larval survival and growth rates, we demonstrated the time spent by R. grandis larvae to wound and kill their prey to be the main factor limiting their development. This factor may be considerably influenced by the proportions of diseased, wounded or molting prey rise in the brood system, for instance as a result of an increase in prey density, or due to the presence of conspecific adults (which wound their prey but do not consume them entirely). Furthermore, our tests suggest that no cannibalism or noticeable intraspecific competition occurred between R. grandis larvae, whereas some lighter mode of competition probably took place. <p>R. grandis also exhibits a reproductive numerical response to prey density, which mainly relies on the perception of chemical stimuli and inhibitors released in the bark beetle brood system. In the current study, we developed a non-destructive approach to follow the dynamics of volatile compound production, using sequential sample collection on SPME fibers. Our tests demonstrated that the larval activity of D. micans or D. valens strongly influences the release of some oxygenated monoterpenes. However, our attempts to correlate the relative quantities of some identified chemicals to offspring production were less successful as it concerns the identification of potential oviposition stimuli and inhibitors. <p>The problematic rose by the progression of D. micans, as well as detailed results of each of the described above studies are discussed in the two published papers and the three manuscripts forming this thesis. Bringing all these studies together, several perspectives are also presented in the general discussion. <p>/<p>Ravageur des épicéas, Dendroctonus micans est toujours en voie d’extension en France, en Turquie, en Angleterre et au Pays de Galles. Dans la plupart de ces zones, le dendroctone est accompagné de manière naturelle par son prédateur monospécifique, Rhizophagus grandis. Depuis les années 1960, le prédateur a également fait l’objet d’une production de masse et de programmes de lâchers dans les zones d’arrivée récente du scolyte.<p>Dans le cadre de la lutte biologique contre D. micans, les gestionnaires forestiers doivent donc estimer au plus tôt la présence du ravageur dans des zones jusque là indemnes, mais également vérifier l’établissement du prédateur par progression naturelle ou résultant d’introductions délibérées. Dans la présente étude, nous avons démontré l’efficacité de pièges d’interception appatés à l’aide de monoterpènes oxygénés pour la capture de R. grandis. Celle-ci s’est faite dans différentes conditions épidémiologiques, incluant notamment des zones situées en arrière du front de progression du scolyte et des zones où des lâchers artificiels ont été réalisés. Comme R. grandis est strictement inféodé au dendroctone, un autre avantage de la technique est la possibilité de réaliser un dépistage indirect du ravageur dans les zones où son statut est incertain (zones en cours de colonisation, ou considérées comme à risque à moyen terme).<p>Par ailleurs, R. grandis est également considéré comme un des meilleurs ennemis naturels potentiels pour lutter contre d’autres espèces de Dendroctonus aggressifs. Dans cette optique, R. grandis a été récemment utilisé dans un programme de lute biologique contre D. valens, ravageur invasif arrivé en Chine dans la fin des années 1990 en provenance d’Amérique du Nord. Nous avons démontré la capacité de R. grandis à s’introduire et à se reproduire dans les galeries de D. valens lors de tests de laboratoire, mais aussi sur des arbres vivants en pinèdes. <p>En Europe, R. grandis est strictement inféodé aux galeries de D. micans, où larves et adultes du prédateur s’attaquent aux larves grégaires du scolyte. Dans ce système clos, la réponse fonctionelle de R. grandis est influencée par plusieurs facteurs étroitement corrélés, la densité de proies, la densité de prédateurs, et la distribution des proies. En mesurant l’efficacité de prédation de R. grandis en termes de survie des larves et de taux de croissance, nous avons démontré l’influence sur leur développement du temps passé par les larves à blesser et à tuer leurs proies. Ce facteur est par ailleurs fortement dépendant de la proportion de larves malades, blessées ou en cours de mue au sein du système ;une proportion qui peut augmenter en réponse à une augmentation de la densité de proies, ou lorsque des adultes sont présents (ceux-ci blessent les proies mais ne les consomment pas entièrement). Enfin, nos tests suggèrent qu’il n’existe que peu de cannibalisme ou de compétition intraspécifique entre larves de R. grandis, tandis que des modes de compétition moins importants prennent vraisemblablement place.<p>R. grandis présente également une réponse numérique reproductive à la densité de proies disponibles, principalement basée sur la perception de stimuli et d’inhibiteurs présents dans les galeries du scolyte. Par la collecte de composés volatils présents dans ces systèmes à l’aide de fibres SPME, nous avons développé une méthode non-destructive pour suivre la dynamique de production des médiateurs chimiques. Nos tests ont démontré que l’activité des larves de D. micans ou D. valens influence fortement la dynamique de production de certains monoterpènes oxygénés. En revanche, il n’a pas été été possible de corréler les différents composés identifiés au nombre de larves de R. grandis présentes dans le système. <p>La problématique soulevée par la progression de D. micans, de même que les résultats détaillés de chacune des études décrites ci-dessus sont discutés dans les deux papiers publiés et les trois manuscrits formant cette thèse. Les différentes perspectives apportées par ce travail sont également présentées dans la discussion générale.<p><br>Doctorat en Sciences agronomiques et ingénierie biologique<br>info:eu-repo/semantics/nonPublished
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Li, Yinping. "Effects of the rove beetle, Dalotia coriaria, on western flower thrips, Frankliniella occidentalis, under laboratory conditions; and integrating the entomopathogenic fungus, Beauveria bassiana, with D. coriaria to suppress western flower thrips populations under greenhouse conditions." Diss., 2018. http://hdl.handle.net/2097/39365.
Full textAbstract:
Doctor of Philosophy<br>Department of Entomology<br>Raymond A. Cloyd<br>Western flower thrips, Frankliniella occidentalis, is one of the most destructive insect pests in greenhouse production systems due to direct and indirect plant damage resulting in substantial economic losses. In addition, western flower thrips has developed resistance to many insecticides. Therefore, alternative plant protection strategies are warranted, such as augmentative biological control. This research was designed to evaluate 1) the effect of different absolute numbers of predator (rove beetle, Dalotia coriaria) and prey (western flower thrips) on predation efficacy of rove beetle under laboratory conditions; 2) the effect of western flower thrips pupal stage, predator-prey ratio, predator-prey number, and searchable area on predation efficacy of rove beetle in the laboratory; and 3) the effectiveness and cost of integrating the entomopathogenic fungus, Beauveria bassiana, and the rove beetle, D. coriaria, in suppressing western flower thrips populations under greenhouse conditions.
Three laboratory experiments were conducted to assess predation efficacy of rove beetle adults on three western flower thrips pupal stages [prepupa, pupa, and prepupa-pupa combination (50%:50%)]. In each experiment, there were six numbers (0, 1, 2, 3, 4, and 5) of rove beetle adults and four initial numbers (15, 20, 25, and 30) of one western flower thrips pupal stage. This treatment configuration allowed for assessing the effect of predator-prey ratios (1:5, 1:10, and 1:15), accounting for different initial prey numbers, on predation efficacy of the rove beetle. Overall, for each pupal stage, the estimated mean probability of western flower thrips adults captured on yellow sticky cards decreased as the number of rove beetle adults released increased from 1 to 3, although the effect of additional rove beetle adult releases was not apparent. Furthermore, across the pupal stages considered in this study, in general, there was no evidence of any differences due to predator-prey ratios or initial prey numbers within each predator-prey ratio.
Two laboratory experiments were conducted to assess the effects of western flower thrips pupal stage, predator-prey ratio, predator-prey number, and searchable area on predation efficacy of rove beetle adults. In experiment 1, there were two western flower thrips pupal stages (prepupa and pupa), three predator-prey ratios (rove beetle:western flower thrips—1:5, 1:10, and 1:15), and three predator-prey numbers (2, 3, and 4 times). Experiment 2 evaluated the latter two factors in combination with searchable area defined by container sizes [15.2 cm (1,834.82 cm3) and 11.5 cm (701.79 cm3)]. The estimated mean probability of western flower thrips adults captured on yellow sticky cards was significantly higher for the 1:5 predator-prey ratio [61.1% (48.5-72.4%)] than 1:10 [39% (28.1-51.2%)] and 1:15 predator-prey ratio [34.7% (24.7-46.3%)]. The estimated mean probability of western flower thrips adults captured on yellow sticky cards for 2 times the predator-prey number [57% (44.3-68.8%)] was significantly higher than 3 [37.2% (26.6-49.3%)] and 4 [40.6% (30-52.3%)] times the predator-prey number. In addition, a significantly higher estimated mean probability of western flower thrips adults was captured on the yellow sticky cards in the 15.2 cm than 11.5 cm containers.
Two greenhouse experiments were conducted that evaluated five treatments: combination of insecticides (spinosad, pyridalyl, chlorfenapyr, and abamectin), B. bassiana, D. coriaria, B. bassiana and D. coriaria combination, and a water control. Overall, the estimated mean number of western flower thrips adults captured on yellow sticky cards was significantly lower for the insecticide treatment (mean range: 0, 46) than for the B. bassiana and D. coriaria combination (mean range: 0.3, 105.1) over eight weeks. There were no significant differences in final foliage quality of chrysanthemum, Dendranthema x grandiflorum, plants among the five treatments in experiment 1, but there were significant differences in experiment 2. However, in experiment 2, the chrysanthemum plants across all treatments were not marketable due to substantial feeding damage by western flower thrips. The cost of the insecticide treatment was nearly twice that of the B. bassiana and D. coriaria combination ($963.50 vs. $495.67) and was over twice that of the B. bassiana only treatment ($963.50 vs. $417.04). The D. coriaria only treatment was the least expensive at $78.63.
The results of the research provide insight into the predatory behavior of D. coriaria on western flower thrips pupal stages, which may have practical implications for greenhouse production systems. However, predation efficacy of rove beetle adults on western flower thrips is influenced by predator-prey ratio, predator-prey number, and searchable area. Finally, greenhouse producers must initiate insecticide applications or release rove beetle adults early in the production cycle when western flower thrips populations are low to minimize plant damage.
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Ward, Meredith Curran William Stevenson. "Ecological weed management the role of ground beetles in weed seed predation /." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-3564/index.html.
Full text
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(8066012), Ivan Grijalva. "Impact of Insecticides on Cucumber Beetles (Coleoptera: Chrysomelidae) and Spider Predators in Watermelon and Corn." Thesis, 2019.
Find full textAbstract:
<p>The
primary goal of this research study was to provide updated pest management
recommendations to growers, including the reduction of insecticide applications
on a calendar basis by the use of pest economic thresholds, with the purpose of
maximizing insecticide efficacy while minimizing the associated negative
impacts on natural enemies and their ecosystem services. </p>
<p>Commercial
watermelon (<i>Citrullus lanatus</i>) production in the Midwest
typically relies on neonicotinoid and pyrethroid insecticides to manage insect
pests, particularly striped and spotted cucumber beetles (<i>Acalymma vittatum </i>Fabricius and <i>Diabrotica undecimpunctata</i> <i>howardi</i>
Barber, respectively). The role of arthropod predators in managing cucumber
beetles is not well documented, and data
on the effects of insecticides on predators in watermelon production are deficient.
Common cucumber beetle predators include coccinellid beetles found on plants,
ground-dwelling carabid beetles (Coleoptera: Carabidae) and spiders in several
families that inhabit the soil surface in watermelon fields. I hypothesize that these generalist predators
and the ecosystem services (e.g., pest predation) they provide are at risk from
insecticides used for pest management without regard to economic thresholds. My
study compared the effect of insecticide use on cucumber beetle pests, spider
predators, collembola populations and field pest predation under two
treatments: 1) watermelons treated with
neonicotinoid soil drench and subsequent pyrethroid sprays, surrounded by corn
with neonicotinoid-treated seeds (Conventional),
and 2) watermelons treated only with pyrethroid spray when economic thresholds
were reached, surrounded by corn with untreated seeds (IPM).</p>
<p>The frequent application of
insecticides decreased cucumber beetles in the
watermelon plots managed with Conventional pest management; however, they also reduced spider predators,
collembola densities, and field pests predation measurements, possibly due to
the subsequent pyrethroids applications during the growing season. In addition, our study showed that
neonicotinoid seed treatment in corn had no negative impact on any of the above-mentioned
response variables measured. </p>
<p>Ultimately, following an IPM strategy and the
use of pest monitoring helped to reduce unnecessary insecticides applications, conservation
of pest regulatory services provided by natural enemies, and possibly less ecological
impact to manage significant insect pests in watermelon plots. <b><br>
</b></p>
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Byrne, Marcus John. "Mechanisms tha allow coexistence of three closely related species of predatory beetle." Thesis, 1998. http://hdl.handle.net/10539/22060.
Full textAbstract:
Submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in fulfilment of the degree of Doctor of Philosophy
Johannesburg, South Africa.
April 1998<br>Tottenham (Coleoptera: Staphylinidae) were found to co-occur throughout a large
expanse of Africa, apparently coexisting in the same habitat. The biology of the
three species was investigated to establish the extent of this co-occurrence, and to
explore the mechanisms, if any, by which these three species coexist.
[Abbreviated Abstract. Open document to view full version]<br>MT2017
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"Mate choice, predation and chemical defense in two species of alpine leaf-beetles." 2005. http://doc.rero.ch/lm.php?url=1000,40,4,20051027085201-VY/1_these_LabeyrieE.pdf.
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Brunke, Adam. "DIVERSITY, HABITAT USE AND POTENTIAL BIOCONTROL SERVICES OF ROVE BEETLES (COLEOPTERA: STAPHYLINIDAE) IN SOYBEAN AGROECOSYSTEMS AND ADJACENT HEDGEROWS." Thesis, 2011. http://hdl.handle.net/10214/2838.
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Rove beetles (Staphylinidae) in Ontario soybean-hedgerow agroecosystems were surveyed in 2009-2010 to identify common, widespread species and assess their potential biological control of Soybean Aphid and Bean Leaf Beetle. The spatiotemporal distributions, habitat use, and co-occurrence of staphylinids with soybean pests were studied to provide a framework for future agroecological studies of biocontrol services in soybean. A taxonomic review of the Staphylinina (Staphylinidae: Staphylininae) (‘large rove beetles’) for the geographic area of study was conducted and identification keys were created to assist in future staphylinid research. Common soybean staphylinids were generally exotic, penetrated field interiors, utilized hedgerow habitat outside the growing season and co-occurred with pest populations during vulnerable life stages. Several species exhibited nocturnal activity in soybean foliage. Biocontrol of overwintering Soybean Aphid and Bean Leaf Beetle populations in hedgerows by staphylinids may occur in buckthorn canopies and leaf litter, respectively.
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Sobek, Stephanie. "Spatiotemporal patterns of insect diversity and multitrophic interactions across a tree diversity gradient." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-AD22-F.
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Renkema, Justin Marten. "THE EFFECTS OF GROUND-FLOOR MANAGEMENT ON BLUEBERRY MAGGOT (RHAGOLETIS MENDAX CURRAN) AND PREDATORY BEETLES IN HIGHBUSH BLUEBERRIES." 2011. http://hdl.handle.net/10222/14145.
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There is very low tolerance for blueberry maggot (Rhagoletis mendax Curran) in blueberries making it a serious pest in eastern North America. Control is focused on eliminating flies with insecticides before oviposition in fruit. Organic mulches may improve highbush blueberry production, but their effects on this pest are largely unknown. The research in this thesis evaluated compost and pine needle mulches on blueberry maggot (mature maggots, pupae, emerging flies) and predatory beetles that may consume these stages.
Mulches affected fly emergence and maggot pupation. Fly emergence was reduced by 80-100% and delayed ~8 days from pupae covered with 20 cm of pine needles compared to 1 cm of soil. Emergence from 20 cm of compost was lower in wet conditions, and 5 cm of mulch did not limit emergence in the field. Pupation at increased depth reduced emergence because flies did not eclose or, if eclosed, were unable to crawl to the surface. The delay was likely due to lower temperatures at depth. No flies emerged from 1 cm in pine needles in the field probably due to high temperatures. In the laboratory, maggots pupated more deeply in pine needles than other substrates, but ~30% did not pupate in dry pine needles. Saturated soil caused ~50% of maggots to pupate on the surface.
Mulching altered beetle diversity and activity/density and affected beetle predation on maggots and pupae. Compost plots in a highbush blueberry field attracted predatory carabids and staphylinids, although some staphylinids were frequent in pine needles and phytophagous carabids preferred unweeded compost plots. Attraction to compost, particularly for Pterostichus melanarius (Illiger), was due primarily to higher prey densities - earthworms and millipedes - than other treatments. This beetle consumed some maggots or pupae in soil or compost, but predation rates decreased when alternative prey was abundant.
Blueberry bushes in weedy compost plots attracted many flies, but infestation rates were higher in composted bushes only in the year mulch was applied. Overall, thick mulching with pine needles contributes most significantly to blueberry maggot management. Future research should explore integration of mulch with other tactics for R. mendax control.
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Makwela, Maria Mammolawa. "Biodiversity of predatory beetle groups, carabidae and coccinellidae and their role as bioindicators in wheat agroecosystems." Diss., 2019. http://hdl.handle.net/10500/26902.
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Predatory Ground beetles (Coleoptera: Carabidae) and Lady beetles (Coleoptera: Coccinellidae) are two of the most diverse groups found in wheat agroecosystems, globally. These groups are important from both an economic and ecological perspective due to their natural services provision. The effect of wheat agroecosystem management on species diversity, abundance, biomass and composition in South Africa is not yet documented, and there is no existing data indicating which predatory carabid and coccinellid species provides essential ecosystem services and bioindicator roles. Therefore, we examined the effects of organic, conventional and intercropped agroecosystems on ground beetle and lady beetle abundance, dried weight (biomass), composition and diversity. Sampling of wheat agroecosystems was conducted in three systems i.e. organic, conventional and organic intercropped. Post-hoc Tukey test indicated a statistically significant difference between species diversity, biomass and abundance in organic and intercropped systems compared to the conventional systems. Regression analysis indicated significant positive correlation between aphid’s density and predatory carabid and coccinellid beetles in the intercropped systems. Amongst the weather factors temperature influenced aphid density and carabid and coccinellid beetles’ abundance. PCA (Principal Component Analysis) revealed significant positive correlation between individual biomass and cropping system. Conventional system showed a negative correlations with carabid and coccinellid individual biomass. We found that some carabid and coccinellid species can be used to measure the quality of agroecosystems. This study provides a fundamental basis for identification and monitoring of carabid and coccinellid species and their role as bioindicators of ecological disturbance. The identified bioindicator species in this study can assist in developing conservation and biomonitoring strategies within agroecosystems.<br>Agriculture and Animal Health<br>M. Sc. (Agriculture)
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Feng, Wen-Bin, and 馮文斌. "The effect of insecticide exposure on intraspecific variation of life history traits in agricultural generalist predator Paederus beetle." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/699f8t.
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碩士<br>國立中興大學<br>昆蟲學系所<br>106<br>The tradeoff of life history trait in the evolution of insecticide resistance is common in insect owing to energy acquisition mainly channels for detoxifying enzyme purposes. In addition, acute exposure of insecticide may also elicit impact on physiology and behavior on survived insects. The rove beetle, Paederus fuscipes Curtis, is a beneficial insect that suppresses agricultural pest populations in agroecosystems. However, as with other agricultural pests, massive input of pesticides may have led to selection of resistance in populations of Paederus beetles. Hence, any change of life history traits of Paederus beetle may disrupt their ecosystem service or facilitate their invasion in human setting. In the study, we determined median lethal time of ten field-collected strains in Taiwan against three insecticides that commonly employed to manage agricultural pests including imidacloprid, cyhalothrin and fenitrothion. We exhibited that the toxicities of cyhalothrin and fenitrothion were similar among strains (1 to 4-fold) but significant difference among tested strains was detected in imidacloprid treatment (1 to 16-fold). The effect of long term exposure of imidacloprid on life history traits of Paederus beetle was limited, in which only egg incubation and adult longevity were significantly compensated in the evolution of insecticide resistance. In particular, the egg incubation period was prolonged and adult longevity was reduced along with increasing of imidacloprid resistance. The sublethal effect of imidacloprid on biological attributes of offspring and adult fecundity was investigated on two strains with different level of imidacloprid resistance. The adult sex ratios were slightly female-biased in most combinations. The quality of offspring, particularly eggs, was significantly decrease when adults of Ji strain were sublethal exposed to imidacloprid. In addition, hormetic effect was apparent in Ji strain as mean fecundity per female increase from 12.80 ± 8.95 (±SE) to 42.70 ± 13.77 (±SE) eggs in comparison with those of control (7.10 ± 1.32 (±SE)). However, the phenomenal was rather inconsistent among strains tested possibly owing to difference in insecticide resistance level as reproductive compensation was absent in the resistant population.
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Hazzard, Ruth V. "Coleomegilla maculata (DeGeer) predation on eggs of Colorado potato beetle, Leptinotarsa decemlineata (Say)." 1989. https://scholarworks.umass.edu/theses/3055.
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Erbilgin, Nadir. "Association, population dynamics, and underlying behaviors of bark beetle predators in the health of red pine plantations." 2001. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Rothenwöhrer, Christoph. "Plant-herbivore-predator communities and grassland management intensity - Implications for biodiversity conservation practices on local and landscape scales." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-F18D-9.
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Kalibbala, Faith Nandawula. "The performance of the seed feeding bruchid beetle Sulcobruchus subsuturalis (Pic) (Cleoptera: Bruchidae) in the biological control of Caesalpinia decapetala (Roth) Alston (Fabaceae) an invasive weed in South Africa." Thesis, 2009. http://hdl.handle.net/10539/6785.
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The release of the seed eating beetle Sulcobruchus subsuturalis for biological control of
Caesalpinia decapetala in South Africa has been ongoing since 2000. This is the first
post release evaluation of the efficacy of the agent against the weed. The study assessed
the phenology of C. decapetala and S. subsuturalis at two sites and included determining
the establishment of the beetle on the target weed at 25 study sites. In addition, the effects
of S. subsuturalis on seed densities as well as seed germination and seedling recruitment
were examined. Furthermore predation by native ants and attacks by native parasitoids
were also examined at two release sites. Mature filled pods were available on the tree
from September (spring) to March (summer) when the beetle is expected to be
reproductively active. The majority of beetle releases by Working for water took place in
summer. However the proportion of beetle infested seeds, which were only recovered
inside pods in the tree canopy at study sites, was low (0 to 15.5%). Consequently high
seed densities and seedling recruitment were observed in the field. In the laboratory, S.
subsuturalis did not lay eggs on buried seeds, however seed infestation levels were
generally high. Only 8.3% of the seeds containing adults germinated and 6.3% emerged
into seedlings. Of the seeds containing larvae, only 14.6% germinated and 2.1% emerged
into seedlings. Thus far, S. subsuturalis has failed to maintain high populations on the
target weed, possibly due to egg predation by native ants (Crematogaster species,
Pheidole megacephala, Messor natalensis and Tetramorium avium) and attacks by native
parasitoids. Egg predation reached 100% within 10 days. Egg parasitism by unknown
parasitoids ranged between 80 and 93.1% in Limpopo. The parasitic wasp Dinarmus
altifrons was recovered once developing inside a C. decapetala seed infested with S.
subsuturalis. Further investigations regarding attacks by indigenous parasitoids on S.
subsuturalis are required to determine the extent of this problem. Meanwhile releases of
S. subsuturalis against C. decapetala should continue. However release efforts need to be
improved by (a) using inundative rather than inoculative releases (b) Releasing every
year between September and March (summer) and (c) involving land owners, farmers
and nature reserve authorities in release activities. Ultimately an additional agent should
be sought for release against C. decapetala as the weed may not be the preferred host for
S. subsuturalis.
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von, Fragstein und Niemsdorff Paul-Albin Maximilian. "Tritrophic interactions between Populus tremula, leaf beetles and their natural enemies - from the field to the laboratory." Thesis, 2011. http://hdl.handle.net/11858/00-1735-0000-0006-B3AF-8.
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