Odour Choice Research Articles

Nucleus accumbens core dopamine D2 receptors are required for performance of the odor span task in male rats.

The nucleus accumbens (NAc) core gates motivationally relevant behavioral action sequences through afferents from cortical and subcortical brain regions. While the role of the NAc core in reward and effort-based decision making is well established, its role in working memory (WM) processes is incompletely understood. The odor span task (OST) has been proposed as a measure of non-spatial working memory capacity (WMC) as it requires rodents to select a novel odor from an increasing number of familiar odors to obtain a food reward. To assess the role of the NAc core in the OST using (1) reversible chemical inactivation and (2) selective blockade of dopamine D1 and D2 receptors in the area. Well-trained male rats were tested on the OST following intra-NAc core infusions of muscimol/baclofen, the D1 receptorantagonist SCH-23390 (1 μg/hemisphere) and the D2 receptorantagonist eticlopride (1 μg/hemisphere). Behavioral measurements included the average odor span, maximum odor span, choice latency, searching vigor, and patterns of responding during foraging that may relate to impulsivity. Chemical inactivation of the NAc core significantly decreased odor span relative to sham and vehicle conditions. Selective antagonism of D2, but not D1, receptors in the NAc core also produced deficits in odor span. We found that secondary behavioral measures of choice latency, searching vigor, and responding to the first odor stimulus encountered were largely unaffected by treatment. These findings suggest that D2 receptors in the NAc core are required for OST performance.

Analysis of Genes Associated with Feeding Preference and Detoxification in Various Developmental Stages of Aglais urticae.

Herbivorous insects and host plants have developed a close and complex relationship over a long period of co-evolution. Some plants provide nutrients for insects, but plants' secondary metabolites also influence their growth and development. Urtica cannabina roots and leaves are poisonous, yet Aglais urticae larvae feed on them, so we aimed to clarify the mechanism enabling this interaction. At present, studies on the detoxification mechanism of the A. urticae are rare. In our study, first, we used the A. urticae larval odor selection behavior bioassay and choice feeding preference assay to analyze the feeding preferences of A. urticae on its host plant, U. cannabina. Next, we used transcriptome sequencing to obtain the unigenes annotated and classified by various databases, such as KEGG and GO. In this study, we found that U. cannabina could attract A. urticae larvae to feed via scent, and the feeding preference assay confirmed that larvae preferred U. cannabina leaves over three other plants: Cirsium japonicum, Cannabis sativa, and Arctium lappa. The activity of detoxifying enzymes GST and CarE changed in larvae that had consumed U. cannabina. Furthermore, through transcriptomic sequencing analysis, 77,624 unigenes were assembled from raw reads. The numbers of differentially expressed genes were calculated using pairwise comparisons of all life stages; the expression of detoxification enzyme genes was substantially higher in larvae than in the pupal and adult stages. Finally, we identified and summarized 34 genes associated with detoxification enzymes, such as UDP-glucose 4-epimerase gene, 5 Glutathione S-transferase genes, 4 Carboxylesterase genes, 4 Cytochrome P450 genes, 10 ATP-binding cassette genes, 4 Superoxide dismutase, and Peroxidase. Moreover, we identified 28 genes associated with the development of A. urticae. The qRT-PCR results were nearly consistent with the transcriptomic data, showing an increased expression level of four genes in larvae. Taken together, this study examines the correlation between A. urticae and host plants U. cannabina, uncovering a pronounced preference for A. urticae larvae toward host plants. Consistent with RNA-seq, we investigated the mechanism of A. urticae's interaction with host plants and identified detoxification-related genes. The present study provides theoretical support for studying insect adaptation mechanisms and biological control.

Social odor choice buffers drug craving.

Social interactions are rewarding and protective against substance use disorders, but it is unclear which specific aspect of the complex sensory social experience drives these effects. Here, we investigated the role of olfactory sensory experience on social interaction, social preference over cocaine, and cocaine craving in rats. First, we conducted bulbectomy on both male and female rats to evaluate the necessity of olfactory system experience on the acquisition and maintenance of volitional social interaction. Next, we assessed the effect of bulbectomy on rats given a choice between social interaction and cocaine. Finally, we evaluated the influence of olfactory sensory experience by training rats on volitional partner-associated odors, assessing their preference for partner odors over cocaine to achieve voluntary abstinence and assessing its effect on the incubation of cocaine craving. Bulbectomy impaired operant social interaction without affecting food and cocaine self-administration. Rats with intact olfactory systems preferred social interaction over cocaine, while rats with impaired olfactory sense showed a preference for cocaine. Providing access to a partner odor in a choice procedure led to cocaine abstinence, preventing incubation of cocaine craving, in contrast to forced abstinence or non-contingent exposure to cocaine and partner odors. Our data suggests the olfactory sensory experience is necessary and sufficient for volitional social reward. Furthermore, the active preference for partner odors over cocaine buffers drug craving. Based on these findings, translational research should explore the use of social sensory-based treatments utilizing odor-focused foundations for individuals with substance use disorders.

Enhanced olfactory memory detection in trap-design Y-mazes allows the study of imperceptible memory traces in Drosophila.

The neural basis of behavior is identified by systematically manipulating the activity of specific neurons and screening for loss or gain of phenotype. Therefore, robust, high-scoring behavioral assays are necessary for determining the neural circuits of novel behaviors. We report a simple Y-maze design for Drosophila olfactory learning and memory assay. Memory scores in our Y-mazes are considerably better and longer-lasting than scores obtained with commonly used T-mazes. Our results suggest that trapping flies to an odor choice in a Y-maze could improve scores. We postulated that the improved scores could reveal previously undetectable memory traces, enabling the study of underlying neural mechanisms. Indeed, we identified unreported protein synthesis-dependent long-term memories (LTMs), reinforced by ingestion of (1) an aversive compound and (2) a sweet but nonnutritious sugar, both 24 h after training. We also used Y-mazes to probe how using a greater reward may change memory dynamics. Our findings predict that a greater sugar reward may extend existing memory traces or reinforce additional novel ones.

Ocean Acidification Affects Volatile Infochemicals Production and Perception in Fauna and Flora Associated With Posidonia oceanica (L.) Delile

Communication among marine organisms are generally based on production, transmission, and interpretation of chemical cues. Volatile organic compounds (VOCs) can act as infochemicals, and ocean acidification can alter their production in the source organisms as well as the interpretation of the information they drive to target organisms. Two diatoms (Cocconeis scutellum var. parva and Diploneis sp.) and a macroalga (Ulva prolifera), all common epiphytes of Posidonia oceanica leaves, were isolated and cultured at two pH conditions (8.2 and 7.7). Their biomass was collected, and the VOCs produced upon wounding were extracted and analyzed using gas chromatography. Chemotactic reactions of invertebrates triggered by VOCs were tested using a static choice experimental arena and a flow-through flume system. Odor choice experiments were performed on several invertebrates associated with P. oceanica meadows to investigate the modification of behavioral responses due to the growth of algae in acidified environments. Complex patterns of behavioral responses were recorded after exposure to algal VOCs. This study demonstrated that a) ocean acidification alters the bouquet of VOCs released by diatoms and macroalgae and b) these compounds act as infochemicals and trigger peculiar behavioral responses in benthic invertebrates. In addition, behavioral responses are species-specific, dose-dependent, and are modified by environmental constraints. In fact, the static diffusion in choice arenas produced different responses as compared to flow-through flume systems. In conclusion, we demonstrate that in future marine environments higher CO2 concentrations (leading to a pH 7.7 by the end of this century) will modify the production of VOCs by micro- and macroalgae as well as the recognition of these infochemicals by marine invertebrates.

Prostate Cancer-Induced Changes in Urinary Odors at Biomarker Concentrations of PPQ with Validation by Sniffer Mouse Behavioural Assays

Although prostate-specific antigen (PSA) is a significant tumor marker for prostate cancer at present, the low specificity (approximately 33%) and so on likely lead to an overdiagnosis and patient suffering from highly invasive prostate biopsy. Complementary measures with cancer-characteristic biomarkers could improve the specificity and accuracy of diagnosis before the biopsy. Previously, “sniffer mice” were shown to be super-sensitive to differences in odors and to discriminate between odors of urine mixtures from patients with bladder cancer before and after tumor resection as well as urine odors of mice with or without experimental tumors. Here, we showed that the sniffer mice discriminate efficiently urinary odors of patients with prostate cancer using an odor plume-guided Y-maze behavioural assay. Through discrimination training in forced-odor choice, statistically significant increases in correct odor choice rates showed the super-sensitivity of sniffer mice to the olfactory cue of ppq-level urinary biomarkers for prostate cancer in 106 -fold diluted urine samples, where donor-unique odors were below the threshold. Moreover, we validated eight volatile urinary biomarkers nearly at their original relative concentrations as the prostate cancer cue even when adding a similar biomarker profile to the post-radical prostatectomy urine samples by the same behavioural score of the sniffer mice. These biomarkers and profiles could be useful for non-invasive tests for prostate and bladder cancers.

Mushroom body output differentiates memory processes and distinct memory-guided behaviors

The mushroom body (MB) of Drosophila melanogaster has multiple functions in controlling memory and behavior.1-9 However, circuit mechanisms that generate this functional diversity are largely unclear. Here, we systematically probed the behavioral contribution of each type of MB output neuron (MBON) by blocking during acquisition, retention, or retrieval of reward or punishment memories. We evaluated the contribution using two conditioned responses: memory-guided odor choice and odor source attraction. Quantitative analysis revealed that these conditioned odor responses are controlled by different sets of MBONs. We found that the valence of memory, rather than the transition of memory steps, has a larger impact on the patterns of required MBONs. Moreover, we found that the glutamatergic MBONs forming recurrent circuits commonly contribute to appetitive memory acquisition, suggesting a pivotal role of this circuit motif for reward processing. Our results provide principles how the MB output circuit processes associative memories of different valence and controls distinct memory-guided behaviors.

Intoxication Effects on Impulsive Alcohol Choice in Heavy Drinkers: Correlation With Sensation Seeking and Differential Effects by Commodity.

The preference for immediate rewards and high sensation seeking are both potent risk factors for alcohol use disorder (AUD), but how they interact during intoxication is poorly understood. To model decision making linked to AUD risk, we tested heavy drinkers for impulsive choice (delay discounting with alcohol:money or money:money) and behavioral sensation seeking using a novel odor choice task. Laboratory tasks measured actual behavior with real contingencies. Our goals were to determine, in heavy drinkers, (i) alcohol's effects on delay discounting, and (ii) how AUD risk factors relate to delay discounting, and (iii) how delay discounting with alcohol choices compares with strictly monetary choices. Thirty-five heavy drinkers (≥2 binges per month; age=22.8±2.2; 20 male; 5.8±2.3 drinks/drinking day) performed cross-commodity discounting (CCD) of immediate alcohol vs. delayed money, a monetary delay discounting (DD), and behavioral sensation-seeking tasks. CCD and DD were performed while sober and during controlled alcohol infusion targeting 0.08g/dl. The behavioral sensation-seeking task presented binary choices of odorants varying in intensity and novelty, and the risk of exposure to a malodorant. CCD and DD behaviors were highly correlated across conditions, mean r=0.64. Alcohol increased delayed reward preference in DD, p=0.001, but did not alter mean CCD, p>0.16. However, alcohol-induced changes in CCD correlated with behavioral sensation seeking, such that higher sensation seekers' immediate alcohol preference increased when intoxicated, p=0.042; self-reported sensation seeking was uncorrelated, ps>0.08. Behavioral sensation seeking also correlated with "want" alcohol following a priming dose targeting 0.035g/dl, p=0.021. CCD and DD did not correlate with self-reported drinking problems or other personality risk traits. Alcohol increased impulsive alcohol choice in high sensation seekers, suggesting an interaction that may underlie impaired control of drinking, at least in a subset of heavy drinkers-consistent with models highlighting high novelty/sensation-seeking AUD subtypes. Discounting behavior overall appears to be a generalized process, and relatively stable across methods, repeated testing, and intoxication. These findings further support the utility of behavioral tasks in uncovering key behavioral phenotypes in AUD.

Inter- and intra-mouse variability in odor preferences revealed in an olfactory multiple-choice test.

Animals choose between sensory stimuli, a highly complex behavior which includes detection, discrimination, preference, and memory processes. Rodents are reported to display robust preferences for some odors, for instance, in the context of choosing among possible mates or food items. In contrast to the apparent robustness of responses toward these and other "ethologically relevant" odors, little is known about the robustness of behaviors toward odors which have no overt role in the rodent ecological niche, so-called "nonethologically relevant" odors. We developed an apparatus for monitoring the nose-poking behavior of mice and used this apparatus to explore the prevalence and stability of choices among different odors both across mice, and within mice over successive days. Mice were tested with a panel of either ethologically relevant or nonethologically relevant odors in an olfactory multiple-choice test. Significant preferences to nonethologically relevant odors were observed across the population of mice, with longer investigation durations to some odors more than to others. However, we found substantial inter-mouse variability in these responses, and that responses to these odors even varied within mice across days of testing. Tests with ethologically relevant odors revealed that responses toward these odors were also variable across mice, but within individual mice, responses were somewhat stable. This work establishes an olfactory multiple-choice test for monitoring odor investigation, choice, and preference behaviors and the application of this apparatus to assess across- and within-mouse odor-preference choice stability. These results highlight that odor preferences, as assayed by measuring choice behaviors, are variable. (PsycINFO Database Record

Aphicidal effects of terpenoids present in Citrus limon on Macrosiphum roseiformis and two generalist insect predators

The current study is the first report that revealed insecticidal effects of lemon (Citrus limon) peel aqueous extract (LFPAE) against common insect pest of rose, aphids (Macrosiphum roseiformis) and for its influence on useful non-target predators viz., Coccinella septempunctata and Orius laevigatus on rose plants. Effects of LFPAE seemed promising concerning pest and predators of Rosa spp. The LC ESI Q-TOF MS/MS analysis of extract revealed the presence of (l-pipecolic acid, scopoletin, pulegone, γ-terpinene, carvone, menthone, myrcene, limonene, (−)-trans-isopiperitenol, geranial and linalool as active components that may be ascribed to observed effects. Also, some major terpenoids α-pinene, β-pinene, γ-terpinene, menthone, linalool, limonene which are known to be present in lemon were tested for their efficacy. LFPAE did not show any toxicity towards C. septempunctata. However, it was moderately toxic to O. laevigatus. Food choice assays and odor choice assay revealed that there was no significant difference obtained between the percentage of pests/predators that reached a particular choice (LFPAE treated, or untreated rose leaves). According to LC50 values of LFPAE for aphids, the highest toxicity and least value (6.68mg/ml), was obtained at 72h which was almost similar to the lowest concentration tested (×6=6.25mg/ml). Besides at 24 and 48h LC50 values were somewhere around ×2 (100mg/ml) and ×3 (50mg/ml) concentrations. Among all the terpenoids tested at 24–72h, γ-terpinene was most toxic with LC50 value ranging from 0.18 to 0.004mg/ml followed by menthone (0.8–0.008), β-pinene (5.8–0.004), limonene (5.8–0.009), mixture (8.5–0.003), linalool (12.3–0.13) and α-pinene (17.8–0.02), respectively. Field data showed that LFPAE at ×1 (200mg/ml), ×2 and ×3 concentration was effective until nine days after treatment (DAT) and lowest concentration ×4 did not show affectivity beyond seven days. However, terpenoids mixture at ×1 (10mg/ml each) showed affectivity till 11DAT and lower two concentrations (×2 and ×3) caused significant mortality up to 7DAT.

Dynamics of memory-guided choice behavior in Drosophila.

Memory retrieval requires both accuracy and speed. Olfactory learning of the fruit fly Drosophila melanogaster serves as a powerful model system to identify molecular and neuronal substrates of memory and memory-guided behavior. The behavioral expression of olfactory memory has traditionally been tested as a conditioned odor response in a simple T-maze, which measures the result, but not the speed, of odor choice. Here, we developed multiplexed T-mazes that allow video recording of the choice behavior. Automatic fly counting in each arm of the maze visualizes choice dynamics. Using this setup, we show that the transient blockade of serotonergic neurons slows down the choice, while leaving the eventual choice intact. In contrast, activation of the same neurons impairs the eventual performance leaving the choice speed unchanged. Our new apparatus contributes to elucidating how the speed and the accuracy of memory retrieval are implemented in the fly brain.

棉铃虫成虫对两种关键花香气味的联系性学习

PDF HTML阅读 XML下载 导出引用 引用提醒 棉铃虫成虫对两种关键花香气味的联系性学习 DOI: 10.5846/stxb201308142079 作者: 作者单位: 河南农业大学植物保护学院 郑州 450002,河南农业大学植物保护学院 郑州 450002,河南农业大学植物保护学院 郑州 450002,河南农业大学植物保护学院 郑州 450002,河南农业大学植物保护学院 郑州 450002,河南农业大学植物保护学院 郑州 450002,河南农业大学植物保护学院 郑州 450002 作者简介: 通讯作者: 中图分类号: 基金项目: 国家公益性行业(农业)专项资助项目(201203036);河南省教育厅自然科学研究基础项目(12A210012) Associative learning of Helicoverpa armigera adults to two key floral odours Author: Affiliation: Plant Protection College,Henan Agricultural University,Plant Protection College,Henan Agricultural University,Plant Protection College,Henan Agricultural University,Plant Protection College,Henan Agricultural University,Plant Protection College,Henan Agricultural University,Plant Protection College,Henan Agricultural University,Plant Protection College,Henan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了明确棉铃虫对苯乙醛和乙酸苯甲酯两种关键花香气味的联系性学习行为,在室内分别测定了不同学习训练的棉铃虫雌雄成虫对两种关键花香气味的选择偏好性反应和雄成虫的触角电位反应。偏好性测定结果表明,无花香气味接触经历的棉铃虫对苯乙醛和乙酸苯甲酯的选择频次均无显著差异,且单纯的花香气味接触经历也不能诱导棉铃虫气味偏好性的显著改变,唯有花香气味接触经历伴随蔗糖溶液进行强化训练时,才能诱导气味偏好性的显著性改变。从对两种花香气味的联系性学习看,棉铃虫更容易将苯乙醛与蔗糖溶液进行联系性学习,而不容易将乙酸苯甲酯与蔗糖溶液进行联系性学习。从性别差异看,雌虫比雄虫具有更强的将花香气味与蔗糖溶液进行联系性学习的能力。触角电位测定结果表明,不同学习训练的棉铃虫雄成虫对两种花香气味和绿叶气味顺-3-己烯-1-醇的EAG反应值之间不存在显著性差异。总之,花香气味伴随食物资源的联系性学习经历,能够明显提高棉铃虫成虫对花香气味的选择偏好,可以此为基础进一步优化花香引诱剂的配方设计和应用技术。 Abstract:As an important polyphagous agricultural insect pest species, the adults of Helicoverpa armigera (Lepidoptera: Noctuidae) have the traits and habit of feeding various flower nectar as complementary nutrition. Two common floral volatiles, phenylacetaldehyde and benzyl acetate, which being released from a number of nectar host and oviposition host plant species of many moths and exhibited fairly strong attractiveness in previous field trapping experiments, are the key olfactory cues on guiding the flower-visiting behaviour of various moth species, including H. armigera. To elucidate the associative learning ability of H. armigera moths to these floral volatiles, we tested the odour choice preference of the male and female moths after different training treatments (naïve, exposure, and conditioning) in a dual choice bioassay, as well as the electroantennographic (EAG) responses of the male moths to these odours (use cis-3-hexen-1-ol as a reference) after corresponding treatments. The results of the odour preference bioassay manifested that, the choice frequencies of the naïve group (having no contact experience with the floral odours) did not differ significantly between phenylacetaldehyde and benzyl acetate; moreover the exposure treatment (exposure to these odours without the association of food rewarding) could not also induce significant alteration of the odour preference; interestingly, the conditioning treatment (conditioning with the pairs of conditioned stimuli [floral odour] and the unconditioned stimulus [sucrose solution]) significantly altered the odour preference pattern, suggesting that H. armigera moths could associate the olfactory cues with the presence of food reward. Comparison of the learning performance of H. armigera conditioned with different floral odours showed that, phenylacetaldehyde was easier to be associated with sucrose solution than benzyl acetate, and the choice response percents of the males and females to phenylacetaldehyde correspondingly reached up to 70.00% and 67.50% after conditioned, respectively, but the individuals in the benzyl acetate-conditioned group only exhibited a weak discrimination response to the paired odour sources, suggesting that the preference of H. armigera to benzyl acetate was an innate response rather than later learned response. The difference in associative learning between the two sexes was also studied. The results suggested that the female moths had stronger learning capacity of associating floral odours with sucrose solution than that of the male moths, which might be caused by the differential nectar-feeding requirements between sexes, since that three behaviors (feeding, mating, and oviposition) are involved in the life of female moths while oviposition is absent in the life of male moths. The results of EAG recording showed that the EAG responses of all the three male groups (naïve, exposure, and conditioning) to the two floral odours and a green leaf volatile (cis-3-hexen-1-ol) did not differ significantly, suggesting that the associative learning of the males to phenylacetaldehyde occurred at the level of central nervous system rather than at the level of peripheral nervous system such as the olfactory receptor in the antennae. Taken together, the associative learning experience of floral odours paired with food resource could further improve the selection preference of H. armigera moths to the odour used as the conditioned stimulus. Our results provided a foundation for the further optimization of the formula design and field application of floral odour-based attractants on the basis of the associative learning. 参考文献 相似文献 引证文献

Using scalar products to refine the interpretative value of an orientation choice test.

Choice tests, which are often used to examine animal preferences, can be difficult to interpret when no clear choice has been made or when using very young animals which exclude test repetition. We present a new method to evaluate the behavior in a choice test based on the orientation of the animal and illustrate its use when facing those conditions. Using rat pups in an open field maze with a choice of odors, we obtained x,y coordinates of 2 markers (head and body center) using a video-tracking freeware. Two vectors were calculated: an animal orientation vector (body to head) and a perfect orientation vector (body to odor source). The angle between the 2 vectors in each frame was converted into a scalar product ranging from 1 (pup oriented directly towards the odor source) to -1 (facing the opposite direction). A mean scalar product was calculated for each odor source, with the difference between the 2 mean scalar products indicating degree of preference for an odor. The information provided by the mean scalar product difference (MSPD) could not be obtained from other measures, such as binary choice, velocity, or distance moved. The MSPD provides a single, noncategorical value for each animal to describe degree of preference in a choice test. This variable was more effective in differentiating animals, thus allowing a reduction in the number of animals or tests necessary to reach significance.

EPA-1213 – Preference of essential oil as an indicator of individual psychological characteristics

It is known that physiological characteristics of an individual arecorrelated with the formation of a person's emotional background when perceiving external sensory stimuli, as indicated by the close relationshipbetween olfactory and emotiogenicbrain structures. Individual ranking of pleasant and unpleasant odors can be described interms of typological and personality traits, and is associated with persistentpsychological characteristics. We aimed to determine the relationship between preference of essential oil andpsychological individual characteristics. 110healthy volunteers (women and men) -students aged 18 to 23 years with no documented manifestations of rhinalpathologies participated in this study. We used the following tests: ‘Personality differential’, ‘Personality and typological inventory’ by L.N. Sobchik, WAM (Wellbeing, Activity, Mood), and State Anxiety Inventory byC. Spielberger, Y. Hanin. We selected essential oils ofmint, lavender, lemon, rose, common wormwood, pine, ylang-ylang, and sandalwood. Rejection of certain essential oils may be caused by ostensibly real negative personal characteristics, which s/he seeksto get rid of. Amongthose with normal level of anxiety the description of the most pleasant odorwas similar to the description of the real ego. Among those with an anxious accentuation and anxious psychopathythe description of the most pleasant odor and the dynamic ego were similar. Thus, a person consciously hands over a choiceof odor to the personalcharacteristics s/he believes canenhance or rouse positive feelings: subjectively pleasantodors reduced the level of StateAnxiety, improved Wellbeing and Mood, and increased activity.

Encoding of Mixtures in a Simple Olfactory System

Natural odors are usually mixtures; yet, humans and animals can experience them as unitary percepts. Olfaction also enables stimulus categorization and generalization. We studied how these computations are performed with the responses of 168 locust antennal lobe projection neurons (PNs) to varying mixtures of two monomolecular odors, and of 174 PNs and 209 mushroom body Kenyon cells (KCs) to mixtures of up to eight monomolecular odors. Single-PN responses showed strong hypoadditivity and population trajectories clustered by odor concentration and mixture similarity. KC responses were much sparser on average than those of PNs and often signaled the presence of single components in mixtures. Linear classifiers could read out the responses of both populations in single time bins to perform odor identification, categorization, and generalization. Our results suggest that odor representations in the mushroom body may result from competing optimization constraints to facilitate memorization (sparseness) while enabling identification, classification, and generalization.

Smells familiar: group-joining decisions of predatory mites are mediated by olfactory cues of social familiarity

Group-living animals frequently have to trade off the costs and benefits of leaving an established group and joining another group. Owing to their high fitness relevance, group-joining decisions are commonly nonrandom and may be based on traits of both individual members and the group such as life stage, body size, social status and group density or size, respectively. Many group-living animals are able to recognize and to associate preferentially with familiar individuals, i.e. those encountered before. Hence, after dispersing from established groups, animals commonly have to decide whether to join a new familiar or unfamiliar group. Using binary choice situations we assessed the effects of social familiarity on group-joining behaviour of the plant-inhabiting predatory mite Phytoseiulus persimilis. Group living in P. persimilis is brought about by the patchy distribution of its spider mite prey and mutual conspecific attraction. In the first experiment, gravid predator females given a choice between spider mite patches occupied by unfamiliar and familiar groups of females strongly preferred to join familiar groups and to deposit their eggs in these patches. Preference for socially familiar groups was robust across biases of spider mite prey densities between choice options. The second experiment revealed that the predatory mite females can smell social familiarity from a distance. Females subjected to odour choice situations in artificial cages were more strongly attracted to the odour of familiar than unfamiliar groups. We argue that P. persimilis females preferentially join socially familiar groups because a familiar social environment relaxes competition and optimizes foraging and reproduction.

Olfactory Cues Used in Host Selection by Frankliniella occidentalis (Thysanoptera: Thripidae) in Relation to Host Suitability

Olfactory responses of Frankliniella occidentalis (Pergande) to odors from six vegetable host plants-cabbage (Brassica oleracea), lettuce (Lactuca sativa), cucumber (Cucumis sativus), eggplant (Solanum melongena), celery (Apium graveolens) and garlic (Allium sativum) - were measured in choice tests in a Y-tube olfactometer, while host suitability of these same plants was assessed based on life table parameters-development time, survival rates, fertility, offspring sex ratio, female longevity, and an index of population change (I) - measured on leaf disks. Olfactory response was measured on both undamaged and mechanically-damaged plants. Regardless of plant damaged, female F. occidentalis responded positively to the odors of cabbage, lettuce, cucumber, and eggplant, but showed negative responses to celery and garlic, when offered a choice of plant odor or clean air. When female thrips were offered choices between each possible pairing of undamaged plants, or pairings of mechanically-damaged plants, the order of preference was cabbage = lettuce = cucumber > eggplant > celery = garlic. Male thrips responded differently, males responded positively only to undamaged lettuce and eggplant compared to clean air, while among mechanically-damaged plants only cucumber elicited a positive response. Given a choice between all possible pairings of undamaged plants, male thrips preferred lettuce to celery, and eggplant to garlic, whereas among pairings of mechanically-damaged plants male thrips preferred lettuce to celery, and cucumber to eggplant. The order of suitability of the six host plants based on life table parameters for F. occidentalis was essentially the same as the order of preference by female thrips. These results indicate that host plant odor is an important cue for female F. occidentalis in recognizing hosts suitable for oviposition. Information on plant attraction and repellency may be useful in thrips pest management. In addition, the correspondence of preference and performance that we found suggests that evolution of local host adaptation and, perhaps, host specialization, is possible.

Host Plant Selection by Larvae of the Muga Silk Moth,Antheraea assamensis, and the Role of the Antenna and Maxillary Palp

The importance of olfactory senses in food preference in fifth instar larvae of Antheraea assamensis Helfer (Lepidoptera: Saturniidae) was examined by subjecting larvae with only antennae or maxillary palpi after microsurgery to food and odor choice tests. Mean percent consumption, total consumption, and choice indices were used as parameters for drawing conclusions. The foods used were two hosts, two non-hosts, and a neutral medium (water). Both antennae and maxillary palpi were fully competent in preference for host plants, Persea bombycina Kostermans (Laurales: Lauraceae) and Litsea polyantha Juss, over the non-hosts, Litsea grandifolia Teschner and Ziziphus jujuba Miller (Rosales: Rhamnaceae). Both were competent in rejecting the non-hosts, L. grandifolia and Z. jujuba. The odor choice test was carried out using a Y-tube olfactometer and showed similar results to the ingestive tests. The results indicate the necessity of functional integration of a combination of olfactory and gustatory sensilla present in different peripheral organs in food acceptance by A. assamensis larvae.

Acquisition of species-specific perfume blends: influence of habitat-dependent compound availability on odour choices of male orchid bees (Euglossa spp.)

Male orchid bees (Euglossini, Apidae, Hymenoptera) expose species-specific blends of volatile chemicals (perfume bouquets) during their courtship display. The perfumes are acquired by collecting fragrant substances from environmental sources, which are then accumulated in specialised hind leg pouches. To balance the perfume composition, the males need to find and collect the required substances in specific relative amounts while facing seasonal, local or habitat-dependent differences in compound availability. Experience-dependent choice of odours, i.e. 'learned avoidance' of recently collected components, has been proposed as the mechanism that mediates the accumulation of the stereotypical compound ratios. In the present study, we used the presence of certain compounds in male hind leg pouches as proxy for the respective local compound availability, and investigated whether differences in content are correlated with differences in chemical choice assays. Our results suggest that volatile availability differs between localities (n = 16) as well as habitats (n = 2; coastal vs. inland) across the Yucatán peninsula, Mexico, for both studied species. Male Euglossa dilemma showed a pronounced preference for benzyl benzoate and eugenol at locations where those compounds were rare in hind leg extracts, as predicted by the learned avoidance model. No equivalent correlations were found for Euglossa viridissima. This is the first study to combine chemical analyses of perfumes with bioassays of odour choice. It strengthens the view that negative feedback from collected odours modifies future chemical choice and helps males to acquire specific perfume blends.

Host feeding experience affects host plant odour preference of the polyphagous leafminer Liriomyza bryoniae

AbstractHerbivorous insects use highly specific volatiles or blends of volatiles characteristic to particular plant species to locate their host plants. Thus, data on olfactory preferences can be valuable in developing integrated pest management tools that deal with manipulation of pest insect behaviour. We examined host plant odour preferences of the tomato leafminer, Liriomyza bryoniae (Kaltenbach) (Diptera: Agromyzidae), which is an economically important agricultural pest widespread throughout Europe. The odour preferences of leafminers were tested in dependence of feeding experiences. We ranked host plant odours by their appeal to L. bryoniae based on two‐choice tests using a Y‐tube olfactometer with five host plants: tomato, Solanum lycopersicum Mill.; bittersweet, Solanum dulcamara L.; downy ground‐cherry, Physalis pubescens L. (all Solanaceae); white goosefoot, Chenopodium album L. (Chenopodiaceae); and dead nettle, Lamium album L. (Lamiaceae). The results imply that ranking of host plant odours by their attractiveness to L. bryoniae is complicated due to the influence of larval and adult feeding experiences. Without any feeding experience as an adult, L. bryoniae males showed a preference for the airflow with host plant odour vs. pure air, whereas females did not display a preference. Further tests revealed that adult feeding experience can alter the odour choice of L. bryoniae females. After feeding experience, females showed a preference for host plant odour vs. pure air. Feeding experience in the larval stage influenced the choice by adults of both sexes: for males as well as females reared on bittersweet the odour of that plant was the most attractive. Thus, host feeding experience both in larval and/or adult stage of polyphagous tomato leafminer L. bryoniae influences host plant odour preference by adults.