Academic literature on the topic 'Y-tube olfactometer'

AbstractThe rewarding orchid, Cremastra appendiculata (Orchidaceae), has a strong floral scent and is pollinated by long-tongued bumble bee queens (Bombus diversus tersatus Smith; Hymenoptera: Apidae). The response of queens of B. diversus tersatus to the scent of C. appendiculata was investigated using a gas chromatography–electroantennographic detector system and Y-tube olfactometer. Gas chromatography–electroantennographic detector analysis of flower extracts showed that seven compounds (nerol, methyl decanoate, methyl dodecanoate, methyl tetradecanoate, methyl hexadecanoate, ethyl dodecanoate, and ethyl tetradecanoate) elicited antennal responses from B. diversus tersatus queens. Further, Y-tube olfactometer test results showed that queens significantly preferred both the flower extracts and synthetic mixture of seven EAD active compounds compared with pentane (a solvent control). These results suggest that floral scents play an important role in attracting queens and promote successful pollination.

The potential of least-toxic compounds to repel adults of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), was explored. Bioassays in olfactometers and Petri dishes were designed to test the hypothesis that DEET (N, N-diethyl-3-methylbenzamide) can effectively repel H. axyridis adults. A bioassay in a y-tube olfactometer indicated that beetles spent significantly less time in the test arm (DEET; 10, 100, and 1,000 μg) than in the control arm (hexane blank) within a 10-min time frame. A bioassay in a 3-neck bulb-tube olfactometer indicated that significantly more beetles avoided the test arm (DEET, 142 μg) than the control arm (hexane blank) within a 40-min time frame. A bioassay in a Petri dish revealed that significantly more beetles avoided filter paper disks treated with DEET (0.1 and 1.0 mg/cm2; aged for 1 d or 5 d) than acetone (the control) within a 60-min time frame. Finally, another bioassay in a Petri dish revealed that significantly more beetles avoided filter paper strips coated with DEET/paraffin (1% or 9% mixture, aged for 1 d or 23 d) than camphor/paraffin (0.1, 1 and 9% mixtures, aged for 1 d or 23 d), or paraffin alone (the control). This investigation suggests that DEET has good potential for repelling H. axyridis adults and should be field-tested on urban structures.

Volatile synomones in tomato plants stimulate search behavior in Trichogramma pretiosum Riley, resulting in increased rates of parasitization in both the laboratory and field. In a Y-tube olfactometer, female T. pretiosum are attracted by volatiles from tomato.

The natural products of plants come as an alternative ecologically more compatiblein substitution to the synthetic insecticides. This study had the objectiveto evaluate the action of 85% Sirinol ® EC (5% of alicin extracted fromgarlic bean, 75% of fuel oils, 20% of surfactant and retentive) on Rhizoperthadominica (F.) and Sitophilus oryzae (L.) in the adult phase in stored wheat,through the assessment of repellent effect on exposed individuals to wheatgrains treated. Therfore, adults of R. dominica and S. oryzae through the useof two methods ‐Petri‐dishes and olfactometer Y shape tube‐ were exposedto 0.5, 1, 5 and 10% concentration of Sirinol ® and Percentage Repellency(PR) was determined. In each of two methods, the maximum PR of Sirinol ®was at concentration of 10%, with the recorded values 71.58% and 50.26%for adults of R. dominica and, 75.79 % and 62.96% for S. oryzae in Petridishesand Y ‐ shape olfactometer tube methods, respectively. It was shownthat S. oryzae were more sensitive to Sirinol® than R. dominica. The interactionbetween concentration and time (concentration × time) was not significantfor adults of two species.

Abstract Bed bugs (Cimex lectularius L.) (Hemiptera: Cimicidae) are obligate hematophagous ectoparasites, and, therefore, must locate suitable hosts to ensure survival and reproduction. Their largely nocturnal activity suggests that chemosensory and thermosensory cues would play critical roles in host location. Yet, the importance of olfaction in host attraction of bed bugs remains unclear. We developed and validated a Y-tube, two-choice olfactometer and tested its suitability for investigating attraction to human odors (from skin swabs). Olfactometer orientation significantly affected the percentage of bed bugs that were activated by human odors, with significantly more bed bugs responding when the olfactometer was oriented vertically (bug introduced at bottom of the olfactometer) compared with all other orientations. Starved (7–10 d) adult males, mated females, and nymphs responded (47–77% moved up the olfactometer and made a choice) when human odors were present in the olfactometer, while starved, unmated females did not respond. Skin swabs from all five human participants elicited high response rates (65–82%), and bed bugs from four different populations responded to skin swabs (40–82% response rate). However, in all assays including those resulting in relatively low response rates, bed bugs exhibited >90% preference for human odors over blank controls. These results provide strong evidence that bed bugs can respond and orient towards human odors, independently of all other host cues. Furthermore, the validated olfactometer should enable rapid and efficient evaluations of bed bug behavioral responses to semiochemicals.

Volatiles emitted by the host’s food would be the first signals used by parasitoids in the host location process and are thought to play an important role in host habitat location. In this study, the olfactory responses ofTheocolax elegans(Westwood), a Pteromalid wasp that parasitizes immature stages of stored-product insect pests developing inside cereal or leguminous grains, to volatiles emitted by healthy wheat grains, their hexane extracts, and different doses of three individual compounds previously identified in cereal grain odors were investigated in Y-tube olfactometer and Petri dish arena behavioral bioassays and electroantennogram recordings. In Y-tube olfactometer bioassays, odors from healthy wheat grains and their hexane extracts were attractive to both sexes ofT. elegans. Moreover, hexane extracts elicited arresting effects in Petri dish arena. The three synthetic compounds valeraldehyde, maltol, and vanillin elicited dose-dependent responses in both male and female adult wasps confirming the capability of the peripheral olfactory systems to perceive cereal volatiles. In behavioral bioassays, different doses of vanillin were significantly attractive to both sexes.

The scale predator Rhyzobius lophanthae Blaisdell was introduced to Guam and Rota to control invasive Aulacaspis yasumatsui Takagi armored scale infestations on the native Cycas micronesica K.D. Hill populations. The predator demonstrated a clear preference for A. yasumatsui infesting adult plants, resulting in 100% seedling mortality due to the lack of a biocontrol of the scale on seedlings. A Y-tube olfactometer was employed to determine if scale-infested seedling leaves were less attractive to R. lophanthae than scale-infested mature tree leaves. Five paired combinations of seedling versus mature tree leaves were used. The R. lophanthae adults navigated toward scale-infested and un-infested leaves of adults and seedlings when paired with an empty chamber. However, a clear preference for adult leaves occurred when paired with seedling leaves. The results were unambiguous in charcoal-filtered air, intermediate in unfiltered air from an open laboratory, and most ambiguous when conducted with unfiltered in-situ air. The number of predators that did not make a choice was greatest for in-situ air and least for charcoal-filtered air. These results indicated that the substrate used in olfactometry influenced the results, and interpretations of charcoal-filtered air assays should be made with caution. Volatile chemical cues are involved in R. lophanthae preferring A. yasumatsui located on C. micronesica adults when infested adult and seedling leaves are present.

AbstractPrevious investigations showed that (1) predatory mites use odours volatilizing from spider-mite infested plants for remote prey selection and (2) the response to the volatiles is correlated to the predator's ability to control populations of the prey species. Based on this correlation, it is hypothesized that preselecting predatory mites with the aid of olfactometer experiments will increase the probability of finding an efficient natural enemy. Y-tube olfactometer experiments with 11 species of phytoseiids showed that only four species were attracted by the odour of cassava leaves infested with cassava green mite Mononychellus tanajoa (Bondar). If the hypothesis mentioned above is valid, the probability of finding an efficient natural enemy within this group of four will be higher than finding one by randomly taking a species from the initial group of 11 species. Since testing of phytoseiids with an olfactometer can be done in a few hours, it is suggested that these tests precede more laborious evaluation methods.

Bee responses to floral scent are usually influenced by both innate biases and prior experience. Honeybees are less attracted than bumblebees to tomato flowers. However, little is known about how tomato floral scent regulates the foraging behaviors of honeybees and bumblebees. In this study, the foraging behaviors of the honeybee Apis mellifera and the bumblebee Bombus lantschouensis on tomato flowers in greenhouses were investigated. Whether the two bee species exhibit different responses to tomato floral scent and how innate biases and prior experience influence bee choice behavior were examined. In the greenhouses, honeybees failed to collect pollen from tomato flowers, and their foraging activities decreased significantly over days. Additionally, neither naïve honeybees nor naïve bumblebees showed a preference for tomato floral scent in a Y-tube olfactometer. However, foraging experience in the tomato greenhouses helped bumblebees develop a strong preference for the scent, whereas honeybees with foraging experience continued to show aversion to tomato floral scent. After learning to associate tomato floral scent with a sugar reward in proboscis extension response (PER) assays, both bee species exhibited a preference for tomato floral scent in Y-tube olfactometers. The findings indicated that prior experience with a food reward strongly influenced bee preference for tomato floral scent.

Leaves and fruit of nine apple (Malus x domestica Borkh.) genotypes were evaluated for insect injury in 1998 and 1999. Foliar and fruit injury from 12 insect species was inconsistently affected by genotype. Spraying trees with oil affected neither fruit insect injury nor fruit phytotoxicity. In choice feeding assays, incidence of Japanese beetle (JB) feeding and leaf area consumed was greater for 'Liberty' than for 'York.' Genotypes did not differ in no-choice feeding assays. Choice and no-choice feeding assays between apple and oak indicated that JB could distinguish host plants in an artificial environment. Trichome density appeared different among three genotypes. 'York', the non-preferred genotype, had highest specific leaf weight and concentration of phloridzin, a feeding repellent. 'Liberty' the preferred genotype, had the lowest specific leaf weight, and had the highest concentration of quercitrin, a feeding stimulant. Olfactory stimuli of JB was evaluated with a Y-tube olfactometer. Beetles preferred the side of the Y-tube containing leaf tissue of apple or Virginia creeper over the side with no leaf. Beetles did not choose one plant species over the other. Bias test of beetle orientation in the Y-tube olfactometer indicated that in the morning, but not the afternoon, beetles preferentially moved into the left side of the Y-tube. Humidity did not affect beetle orientation. In darkness JB preferred a leaf disc over a paper disc and beetles tended to remain on the leaf.
Ph. D.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Knowledge about biology and animal behavior is critical to understanding how a particular organism interacts with its environment. Identifying the sex of individuals is an essential step in conducting behavioral studies. An integral part of animal behavior is communication, which can be intermediated by pheromones. Within different groups, insects are the animals use pheromones the most in order to carry out their fundamental activities. Cratosomus flavofasciatus, a Coleoptera of the Curculionidae family, popularly called the Orange-tree-borer, is considered one of the main citrus pests, occurring in Sergipan orchards. The objective of this work was to evaluate the morphological characteristics that allow the sexual differentiation of C. flavosfaciatus and to evaluate the attractiveness of C. flavosfaciatus to the synthetic compounds that make up the pheromone of this species. To verify the sexual dimorphism of C. flavofasciatus, a geometric morphometry analysis was first made using 80 adult individuals of each sex. There were 27 landmarks in the ventral region in each individual. The anatomical landmarks 2, 9, 10, 11, 18, 21 were the ones that contributed most to the distinction between males and females, which represent the region of the rostrum, the final portion of the abdomen and the end of the thorax. For sex confirmation, a withdrawal of the genitalia of both sexes was also performed. In females it was possible to recognize the following structures: sternite VIII and bursa copulatrix. In males, it was possible to observe the gastric spicule and the aedeagus with a pair of parammero. The Procrustes Anova showed significant differences between the sexes (P<0.001) and the size (centroid) in relation to sex (P <0.001), but there was no difference in shape in relation to size (P = 0.229) and the form in relation to sex in conjunction with the size (P = 0.707). Principal component analysis demonstrated an evident differentiation between the genders based on the ventral region of the species. The first two main components explained 51.909% (PC1 + PC2: 39.563% + 12.346%) of the shape variation. The discriminant analysis indicated a significant difference (permutation test = 10,000 permutations; P < 0.001) for the sexual dimorphism of the ventral region. The determination of the adult sex of C. flavofasciatus through the last abdominal sternum is as accurate as the dissection of the genitalia. The behavioral response of C. flavofasciatus to synthetic pheromonal compounds (a mixture of 2-((1R, 2S)-1-methyl-2-(prop-1-en-2-yl)cyclobutil)ethanol (grandisol), (E)-2-(3,3-dimethyl-cyclohexylidene)ethanol (alcohol E) and (Z)-2-(3,3-dimethyl-cyclohexylidene)ethanol (alcohol Z)) and for their host plants Cordia curassavica (Maria-Preta) and Citrus sinensis (Orange Tree) were evaluated by olfactory tests performed on a Y-tube olfactometer. Both sexes were significantly more attracted to C. sinensis stalks (P <0.05) than to filtered air. Tests with C. curassavica stalk attracted only males (P = 0.02). When the insects had the opportunity to choose between C. curassavica stalks and C. sinensis stalks, males preferred those from C. curassavica (P = 0.01), whereas females showed no significant preference (P> 0.05). The combination of the C. curassavica and C. sinensis volatiles associated with the synthetic pheromone at 100ppm concentration was more attractive for both sexes (P <0.05) than for the control (hexane together with the host plant). On the other hand, at the concentration of 10ppm, only the association with C. curassavica attracted males (P = 0.009). These results can be used as a basis for field testing, contributing to the development of an environmentally safe and effective method for monitoring orange tree borer.
O conhecimento sobre a biologia e o comportamento animal é fundamental para compreensão de como determinado organismo interage com o seu ambiente. A identificação do sexo dos indivíduos é um passo essencial na execução de estudos comportamentais. Um ponto integrante do comportamento animal é a comunicação, a qual pode ser intermediada por feromônios. Dentre os vários grupos, os insetos são os animais que mais utilizam os feromônios para desempenhar suas atividades fundamentais. Cratosomus flavofasciatus, um coleóptero da família Curculionidae, popularmente chamado de broca-da-laranjeira, é considerado uma das principais pragas do citros, apresentando grande ocorrência em pomares sergipanos. O presente trabalho teve como objetivo avaliar características morfológicas que permitam a diferenciação sexual de C. flavosfaciatus e avaliar a atratividade de C. flavosfaciatus aos compostos sintéticos que compõem o feromônio de agregação dessa espécie e à suas plantas hospedeiras. Para verificar o dimorfismo sexual de C. flavofasciatus, primeiramente foi feito uma análise de morfometria geométrica utilizando 80 indivíduos adultos de cada sexo. Foram feitos 27 marcos anatômicos (landmarks) na região ventral em cada indivíduo. Os marcos anatômicos 2, 9, 10, 11, 18 e 21 foram os que mais contribuíram para a distinção entre machos e fêmeas, os quais representam a região do rostro, a porção final do abdômen e o final do tórax. Para confirmação do sexo, foi realizada também a retirada da genitália de ambos os sexos. Nas fêmeas foi possível o reconhecimento das seguintes estruturas: esternito VIII e bursa copulatrix. Já nos machos foi possível observar a espícula gastral e o edeago com par de parâmeros. A Anova de Procrustes demonstrou diferença significativa da forma (P < 0,001) e do tamanho (centróide) (P < 0,001) entre os sexos, porém não houve diferença da forma em relação ao tamanho (P = 0,229) bem como da forma em relação ao sexo em conjunto com o tamanho (P = 0,707). A análise de componentes principais demonstrou uma evidente diferenciação entre os sexos com base na região ventral da espécie. Os dois primeiros componentes principais explicaram 51,91% (PC1 + PC2: 39,56% + 12,35%) da variação da forma. A análise de discriminantes indicou diferença significativa (teste de permutação = 10000 permutações; P < 0,001) quanto ao dimorfismo sexual da forma da região ventral. A determinação do sexo em adultos de C. flavofasciatus através do último esternito abdominal é tão precisa quanto à dissecação da genitália. A resposta comportamental de C. flavofasciatus aos compostos feromonais sintéticos (mistura de 2-((1R, 2S)-1-metil-2-(prop-1-en-2-il)ciclobutil)etanol (grandisol), (E)-2-(3,3-dimetilciclohexilideno)etanol (álcool E) e (Z)-2-(3,3-dimetilciclohexilideno)etanol (álcool Z)) e para suas plantas hospedeiras Cordia curassavica (Maria-Preta) e Citrus sinensis (Laranjeira) foi avaliada por meio de testes olfativos realizados em um olfatômetro em “Y”. Ambos os sexos foram significativamente mais atraídos para os caules de C. sinensis (P < 0,05) que para o ar filtrado. Já os testes com caules de C. curassavica atraíram significativamente somente os machos (P = 0,02). Quando os insetos tiveram a oportunidade de escolher entre caules de C. curassavica e caules de C. sinensis, os machos preferiram os de C. curassavica (P = 0,01), já as fêmeas não apresentaram preferência significativa (P > 0,05). A combinação dos voláteis de C. curassavica e C. sinensis associadas ao feromônio sintético na concentração de 100ppm foi mais atrativa para ambos os sexos (P < 0,05) que para o controle (hexano juntamente com a planta hospedeira). Por outro lado, na concentração de 10ppm, somente a associação com C. curassavica atraiu apenas os machos (P = 0,009). Tais resultados podem ser utilizados como base para testes de campo, contribuindo para o desenvolvimento de um método ambientalmente seguro e eficaz para o monitoramento da broca-da-laranjeira.