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The most studied pheromone in Drosophila melanogaster, cis-vaccenyl acetate (cVA), is synthesized in the male ejaculatory bulb and transferred to the female during copulation. Combined with other chemicals, cVA can modulate fly aggregation, courtship, mating and fighting. We explored the mechanisms underlying both cVA biosynthesis and emission in males of two wild types and a pheromonal mutant line. The effects of ageing, adult social interaction, and maternally transmitted cVA and microbes – both associated with the egg chorion – on cVA biosynthesis and emission were measured. While ageing and genotype changed both biosynthesis and emission in similar ways, early developmental exposure to maternally transmitted cVA and microbes strongly decreased cVA emission but not the biosynthesis of this molecule. This indicates that the release – but not the biosynthesis – of this sex pheromone strongly depends on early developmental context. The mechanism by which the preimaginal effects occur is unknown, but reinforces the significance of development in determining adult physiology and behaviour.

The most studied pheromone in Drosophila melanogaster, cis-Vaccenyl Acetate (cVA), is synthesized in the male ejaculatory bulb and transferred to the female during copulation. Combined with other chemicals cVA can modulate fly aggregation, courtship, mating and fighting. It is not detected on the cuticle of isolated males and is only released by males involved in social or sexual interaction. We explored the mechanisms underlying both cVA biosynthesis and emission in males of two wild types and a pheromonal mutant line. The effects of ageing, adult social interaction, and maternally-transmitted cVa and microbes — both associated with the egg chorion— on cVA biosynthesis and emission were measured. While ageing and genotype changed both biosynthesis and emission in similar ways, early developmental exposure to maternally-transmitted cVA and microbes strongly decreased cVA emission but not the biosynthesis of this molecule. This indicates that the release — but not the biosynthesis — of this sex pheromone strongly depends on early developmental context. The mechanism by which the preimaginal effects occur is unknown, but reinforces the significance of development in determining adult physiology and behaviour.Summary statementWe show how the biosynthesis and release of a key Drosophila pheromone is affected by ageing, by early exposure to this pheromone and to microbes, and by social context.

Binary communication systems that involve sex‐specific signaling and sex‐specific signal perception play a key role in sexual selection and in the evolution of sexually dimorphic traits. The driving forces and genetic changes underlying such traits can be investigated in systems where sex‐specific signaling and perception have emerged recently and show evidence of potential coevolution. A promising model is found in Drosophila prolongata, which exhibits a species‐specific increase in the number of male chemosensory bristles. We show that this transition coincides with recent evolutionary changes in cuticular hydrocarbon (CHC) profiles. Long‐chain CHCs that are sexually monomorphic in the closest relatives of D. prolongata (D. rhopaloa, D. carrolli, D. kurseongensis, and D. fuyamai) are strongly male‐biased in this species. We also identify an intraspecific female‐limited polymorphism, where some females have male‐like CHC profiles. Both the origin of sexually dimorphic CHC profiles and the female‐limited polymorphism in D. prolongata involve changes in the relative amounts of three mono‐alkene homologs, 9‐tricosene, 9‐pentacosene, and 9‐heptacosene, all of which share a common biosynthetic origin and point to a potentially simple genetic change underlying these traits. Our results suggest that pheromone synthesis may have coevolved with chemosensory perception and open the way for reconstructing the origin of sexual dimorphism in this communication system., Uniquely among Drosophila species, Drosophila prolongata shows a dramatic male‐specific expansion of the leg chemosensory organs. We show that this change is accompanied by an equally recent evolution of sexually dimorphic pheromones. Long‐chain hydrocarbons that are sexually monomorphic in other species are strongly enriched in D. prolongata males.

The cuticle of all insects is covered with hydrocarbons which have multiple functions. Cuticular hydrocarbons (CHCs) basically serve to protect insects against environmental harm and to reduce dehydration. In many species, some CHCs also act as pheromones. CHCs have been intensively studied in Drosophila species and more specially in D. melanogaster. In this species, flies produce about 40 CHCs forming a complex sex- and species-specific bouquet. The quantitative and qualitative pattern of the CHC bouquet was characterized during the first days of adult life but remains unexplored in aging flies. Here, we characterized CHCs during the whole—or a large period of—adult life in males and females of several wild type and transgenic lines. Both types of lines included standard and variant CHC profiles. Some of the genotypes tested here showed very dramatic and unexpected aging-related variation based on their early days profile. This study provides a concrete dataset to better understand the mechanisms underlying the establishment and maintenance of CHCs on the fly cuticle. It could be useful to determine physiological parameters, including age and response to climate variation, in insects collected in the wild.

International audience; Spiromesifen (Oberon? 240 SC; concentrated solution; Bayer CropScience, Germany) a pesticide derived from spirocyclic tetronic acids, acts mainly though blocking lipid biosynthesis via acetyl-CoA carboxylase. However, its mode of action requires further analyses. This study aims to evaluate the sublethal effects of spiromesifen on the fruit fly Drosophila melanogaster. The treatment was carried out by topical application on newly moulted pupae using two concentrations (LD10 = 21.45 and LD25 = 39.53 ?g a.i./pupa). Our results showed that the developmental duration of larvae and pupae were not significantly affected by treatment. However, spiromesifen caused delayed effects on flies that survived from treated pupae. Spiromesifen was found to decrease significantly both the morphometric measurements and the protein contents of ovaries. The protein pattern of ovaries showed a reduction in the number of protein bands affecting the progeny via vitellogenesis. Finally, compared to controls, spiromesifen decreased significantly the amounts of some cuticular hydrocarbons in treated female and male adults. Consequently, in response to the changes in cuticular hydrocarbons, their sexual behaviour was also affected. Our study brings new insights about the multiple effects and physiological consequences of disturbing lipid metabolism.

Prevention of desiccation is a constant challenge for terrestrial organisms. Land insects have an extracellular coat, the cuticle, that plays a major role in protection against exaggerated water loss. Here, we report that the ABC transporter Oskyddad (Osy)—a human ABCA12 paralog—contributes to the waterproof barrier function of the cuticle in the fruit fly Drosophila melanogaster. We show that the reduction or elimination of Osy function provokes rapid desiccation. Osy is also involved in defining the inward barrier against xenobiotics penetration. Consistently, the amounts of cuticular hydrocarbons that are involved in cuticle impermeability decrease markedly when Osy activity is reduced. GFP-tagged Osy localises to membrane nano-protrusions within the cuticle, likely pore canals. This suggests that Osy is mediating the transport of cuticular hydrocarbons (CHC) through the pore canals to the cuticle surface. The envelope, which is the outermost cuticle layer constituting the main barrier, is unaffected in osy mutant larvae. This contrasts with the function of Snu, another ABC transporter needed for the construction of the cuticular inward and outward barriers, that nevertheless is implicated in CHC deposition. Hence, Osy and Snu have overlapping and independent roles to establish cuticular resistance against transpiration and xenobiotic penetration. The osy deficient phenotype parallels the phenotype of Harlequin ichthyosis caused by mutations in the human abca12 gene. Thus, it seems that the cellular and molecular mechanisms of lipid barrier assembly in the skin are conserved during evolution., Author summary As in humans, lipids on the surface of the skin of insects protect the organism against excessive water loss and penetration of potentially harmful substances. During evolution, a greasy surface was indeed an essential trait for adaptation to life outside a watery environment. Here, we show that the membrane-gate transporter Oskyddad (Osy) is needed for the deposition of barrier lipids on the integument surface in the fruit fly Drosophila melanogaster through extracellular nano-tubes, called pore canals. In principle, the involvement of Osy parallels the scenario in humans, where the membrane-gate transporter ABCA12 is implicated in the construction of the lipid-based stratum corneum of the skin. In both cases, mutations in the genes coding for the respective transporter cause rapid water-loss and are lethal soon after birth. We conclude that the interaction between the organism and the environment obviously implies an analogous mechanism of barrier formation and function in vertebrates and invertebrates.

Diet quality is critical for animal development and survival. Fungi can provide nutrients that are essential to organisms that are unable to synthetize them, such as ergosterol in Drosophila melanogaster. Drosophila studies examining the influence of yeast quality in the diet have generally either provided the diet over the whole life span (larva to adult) or during the adult stage and have rarely focussed on the juvenile diet. Here, we tested the effect of yeast quality in the larval diet on pre-adult development and adult weight, survival, reproduction and food preference. The yeast Saccharomyces cerevisiae was added in three forms in three treatments—live, heated or dried—to food used as the juvenile diet or was not added (empty treatment). Adults resulting from the larvae raised on these four juvenile diets were all maintained on a similar standard laboratory food diet. Our data indicate that yeast quality in the juvenile diet affects larva-to-pupa—but not pupa-to-adult—development. Importantly, adult survival, food preference, mating behaviour and cuticular pheromones strongly varied with the juvenile diet. Therefore, the variation of yeast quality in the pre-adult Drosophila diet affects key adult life traits involved in food search, reproduction and survival.

Animals searching for food and sexual partners often use odourant mixtures combining food-derived molecules and pheromones. For orientation, the vinegar fly Drosophila melanogaster uses three types of chemical cues: (i) the male volatile pheromone 11-cis-vaccenyl acetate (cVA), (ii) sex-specific cuticular hydrocarbons (CHs; and CH-derived compounds), and (iii) food-derived molecules resulting from microbiota activity. To evaluate the effects of these chemicals on odour-tracking behaviour, we tested Drosophila individuals in a wind tunnel. Upwind flight and food preference were measured in individual control males and females presented with a choice of two food sources labelled by fly lines producing varying amounts of CHs and/or cVA. The flies originated from different species or strains, or their microbiota was manipulated. We found that (i) fly-labelled food could attract—but never repel—flies; (ii) the landing frequency on fly-labelled food was positively correlated with an increased flight duration; (iii) male—but not female or non-sex-specific—CHs tended to increase the landing frequency on fly-labelled food; (iv) cVA increased female—but not male—preference for cVA-rich food; and (v) microbiota-derived compounds only affected male upwind flight latency. Therefore, sex pheromones interact with food volatile chemicals to induce sex-specific flight responses in Drosophila.

International audience; Oberon® is a commercial formulation of spiromesifen, a pesticide inhibitor of lipid biosynthesis via acetyl CoA carboxylase, widely used in agricultural crop protection. However, its mode of action requires further analysis. We currently examined the effect of this product on Drosophila melanogaster as a non-target and model organism. Different concentrations of spiromesifen were administered by ingestion (and contact) during pre-imaginal development, and we evaluated its delayed action on adults. Our results suggest that spiromesifen induced insecticidal activity on D. melanogaster. Moreover, spiromesifen treatment significantly increased the duration of larval and pupal development at all tested concentrations while it shortened longevity in exposed males as compared to control males. Also, pre-imaginal exposure to spiromesifen quantitatively affected fatty acids supporting its primary mode of action on lipid synthesis. In addition, this product was found to modify cuticular hydrocarbon profiles in exposed female and male flies as well as their sexual behavior and reproductive capacity.

Prevention of desiccation is a constant challenge for terrestrial organisms. Land insects have an extracellular coat, the cuticle, that plays a major role in protection against exaggerated water loss. Here, we report that the ABC transporter Torr - a human ABCA12 paralog - contributes to the waterproof barrier function of the cuticle in the fruit fly Drosophila melanogaster. We show that the reduction or elimination of Torr function provokes rapid desiccation. Torr is also involved in defining the inward barrier against xenobiotics penetration. Consistently, the amounts of cuticular hydrocarbons that are involved in cuticle impermeability decrease markedly when Torr activity is reduced. GFP-tagged Torr localises to membrane nano-protrusions within the cuticle, likely pore canals. This suggests that Torr is mediating the transport of cuticular hydrocarbons (CHC) through the pore canals to the cuticle surface. The envelope, which is the outermost cuticle layer constituting the main barrier, is unaffected in torr mutant larvae. This contrasts with the function of Snu, another ABC transporter needed for the construction of the cuticular inward and outward barriers, that nevertheless is implicated in CHC deposition. Hence, Torr and Snu have overlapping and independent roles to establish cuticular resistance against transpiration and xenobiotic penetration. The torr deficient phenotype parallels the phenotype of Harlequin ichthyosis caused by mutations in the human abca12 gene. Thus, it seems that the cellular and molecular mechanisms of lipid barrier assembly in the skin are conserved in vertebrates in invertebrates.Author SummaryAs in humans, lipids on the surface of the skin of insects protect the organism against excessive water loss and penetration of potentially harmful substances. During evolution, a greasy surface was indeed an essential trait for adaptation to life outside a watery environment. Here, we show that the membrane-gate transporter Torr is needed for the deposition of barrier lipids on the skin surface in the fruit fly Drosophila melanogaster through extracellular nano-tubes, called pore canals. In principle, the involvement of Torr parallels the scenario in humans, where the membrane-gate transporter ABCA12 is implicated in the construction of the lipid-based stratum corneum of the skin. In both cases, mutations in the genes coding for the respective transporter cause rapid water-loss and are lethal soon after birth. We conclude that the interaction between the organism and the environment obviously implies an analogous mechanism of barrier formation and function in vertebrates and invertebrates.

Sex specific traits are involved in speciation but it is difficult to determine whether their variation initiates or reinforces sexual isolation. In some insects, speciation depends of the rapid change of expression in desaturase genes coding for sex pheromones. Two closely related desaturase genes are involved in Drosophila melanogaster pheromonal communication: desat1 affects both the production and the reception of sex pheromones while desat2 is involved in their production in flies of Zimbabwe populations. There is a strong asymmetric sexual isolation between Zimbabwe populations and all other “Cosmopolitan” populations: Zimbabwe females rarely copulate with Cosmopolitan males whereas Zimbabwe males readily copulate with all females. All populations express desat1 but only Zimbabwe strains show high desat2 expression. To evaluate the impact of sex pheromones, female receptivity and desat expression on the incipient speciation process between Zimbabwe and Cosmopolitan populations, we introgressed the Zimbabwe genome into a Cosmopolitan genome labeled with the white mutation, using a multi-generation procedure. The association between these sex-specific traits was determined during the procedure. The production of pheromones was largely dissociated between the sexes. The copulation frequency (but not latency) was highly correlated with the female—but not with the male—principal pheromones. We finally obtained two stable white lines showing Zimbabwe-like sex pheromones, copulation discrimination and desat expression. Our study indicates that the variation of sex pheromones and mating discrimination depend of distinct—yet overlapping—sets of genes in each sex suggesting that their cumulated effects participate to reinforce the speciation process.

Desaturase1 (desat1) is one of the few genes known to be involved in the two complementary aspects of sensory communication — signal emission and signal reception — in Drosophila melanogaster. In p...

Sex specific traits are involved in speciation but it is difficult to determine whether their variation initiates or reinforces sexual isolation. In some insects, speciation depends of the rapid change of expression in desaturase genes coding for sex pheromones. Two closely related desaturase genes are involved inDrosophila melanogasterpheromonal communication:desat1affects both the production and the reception of sex pheromones whiledesat2is involved in their production in flies of Zimbabwe populations. There is a strong asymmetric sexual isolation between Zimbabwe populations and all other “Cosmopolitan” populations: Zimbabwe females rarely copulate with Cosmopolitan males whereas Zimbabwe males readily copulate with all females. All populations expressdesat1but only Zimbabwe strains show highdesat2expression. To evaluate the impact of sex pheromones, female receptivity anddesatexpression on the incipient speciation process between Zimbabwe and Cosmopolitan populations, we introgressed the Zimbabwe genome into a Cosmopolitan genome labelled with thewhitemutation, using a multi-generation procedure. The association between these sex-specific traits was determined during the procedure. The production of pheromones was largely dissociated between the sexes. The copulation frequency (but not latency) was highly correlated with the female—but not with the male—principal pheromones. We finally obtained two stablewhitelines showing Zimbabwe-like sex pheromones, copulation discrimination anddesatexpression. Our study indicates that the variation of sex pheromones and of mating discrimination depend of distinct—yet overlapping—sets of genes in each sex suggesting that their cumulated effects participate to reinforce the speciation process.

Desaturase1 (desat1) is one of the few genes known to be involved in the two complementary aspects of sensory communication - signal emission and signal reception - in

https://peerj.com/articles/5585/#supplemental-information; International audience; Pheromones are chemical signals that induce innate responses in individuals of the same species that may vary with physiological and developmental state. In Drosophila melanogaster, the most intensively studied pheromone is 11-cis-vaccenyl acetate (cVA), which is synthezised in the male ejaculatory bulb and is transferred to the female during copulation. Among other effects, cVA inhibits male courtship of mated females. We found that male courtship inhibition depends on the amount of cVA and this effect is reduced in male flies derived from eggs covered with low to zero levels of cVA. This effect is not observed if the eggs are washed, or if the eggs are laid several days after copulation. This suggests that courtship suppression involves a form of pre-imaginal conditioning, which we show occurs during the early larval stage. The conditioning effect could not be rescued by synthetic cVA, indicating that it largely depends on conditioning by cVA and other maternally-transmitted factor(s). These experiments suggest that one of the primary behavioral effects of cVA is more plastic and less stereotypical than had hitherto been realised.

The scent apparatus of male Eldana saccharina is a glandular complex on the costal area of the forewing. It consists of two parts; glandular complex 1 is composed of five kinds of cells (epidermal cells, scale cells, glandular cells, supporting cells, duct cells); glandular complex 2 also shows five types of cells (epidermal cells, scale cells, glandular cells, duct cells, trichogen cells). The secretory products of the two parts are discharged into separate ducts which converge before opening onto the lower side of the wing. The male also has two prominent hair-pencils borne on the coremata and large secretory trichogen cells on the genital valves. Each of these exocrine gland components plays an important part in formation of the chemically complex pheromones utilized in the precopulatory behavior of the male.

The exocrine glandular system of the nymphs and the adults of Dysdercus cingulatus were studied. The D. cingulatus nymphs present 3 dorso-abdominal glands (lying under the 3rd, 4th, and 5th abdominal terga) and a pair of dorso-lateral pygidial glands on the pygidium (tergum 8). Histological and ultrastructural studies show that the upper and lower walls of the dorso-abdominal glands differ in structure; 3 types of cells were described: epidermal cells, unicellular secretory cells, and multicellular secretory units. Each of these exocrine glands plays an important part in the behavior of the nymphs (gregariousness, alarm, defense). The morphology of the various glands is discussed, and the chemistry of their secretions and their biological functions are considered.

The toxicity of the non-steroidal ecdysteroid agonist tebufenozide was evaluated topically on adults of the cosmopolitan cockroach Blattella germanica (Blattodea: Blattellidae). The LD50 value was estimated at 402 μg/g of insect (range, 95% fiducial limits: 293–552) at 15 days after treatment. The effects on reproduction were observed in adult females of cockroaches that survived exposure to a LD25 (146 μg/g of insect) of tebufenozide. Dissection of treated females showed a clear reduction in both the number of oocytes per paired ovaries and the size of basal oocytes, as compared to controls. In addition, tebufenozide significantly reduced the mating success of pairs and altered the fertility as shown through the reduction of ootheca development and total absence of viable nymphs. Tebufenozide disrupted the Germancockroach reproduction by interferring with the homeostasis of the insect hormones.

International audience; Shortly after emergence the exoskeleton (cuticle) of adult insects is rapidly expanded, hardened (sclerotized), and pigmented (melanized). In parallel with this process, the oenocytes, which are large polyploid cells located below the abdominal epidermis, secrete onto the cuticle a cocktail of cuticular hydrocarbons (CHs) and waxes. These improve the waterproofing of the cuticle, and also provide important chemosensory and pheromonal cues linked with gender, age, and species differentiation. The hardening and pigmentation of the new cuticle are controlled by the neurohormone, bursicon, and its receptor, encoded by the DLGR2 receptor, rickets (rk); by contrast, little is known about the timecourse of changes in CH profile and about the role of bursicon in this process. Here we show in Drosophila that rk function is also required for the normal maturation of the fly's CH profile, with flies mutant for rk function showing dramatically elevated levels of CHs. Interestingly, this effect is mostly abrogated by mutations in the 119 desaturase encoded by the desaturasel gene, which introduces a first double bond into elongated fatty-acid chains, suggesting that desaturasel acts downstream of rk. In addition, flies mutant for rk showed changes in the absolute and relative levels of specific 7-monoenes (in males) and 7,11-dienes (in females). The fact that these differences in CH amounts were obtained using extractions of very different durations suggests that the particular CH profile of flies mutant for rk is not simply due to their unsclerotized cuticle but that bursicon may be involved in the process of CH biosynthesis itself.

The cuticular hydrocarbons of the fourth-instar larvae of Culex pipiens aged one and six days were analysed by gas chromatography and gas chromatography-mass spectrometry. The effect of an insect growth regulator (halofenozide = RH-0345) on the cuticular hydrocarbons was evaluated using newly moulted fourth-instar larvae of C. pipiens, at the lethal concentrations (LC50 = 12.58 and LC90 = 28.58 µ/l). A previous study revealed that RH-0345 is toxic to larvae of C. pipiens by induction of precocious larval moulting. Several cuticular hydrocarbons (CHCs) were identified and many of the other compounds remained unknown. Our data show that the CHC classes consisted of n-alkanes (C23-C29) and differed quantitatively between larval ages. Significant quantitative differences in the distribution of the hydrocarbons of different chain lengths were observed. Amounts of the CHCs of the treated larvae were shifted towards longer-chain alkanes compared to untreated larvae. Typically, treatment with halofenozide decreas...

ISSN: 2152-2197 ; ESSN: 2152-2219. Editeur commercial : Scientific Research Publishing; International audience; Diflubenzuron (DFB, trade name dimilin® 25 WP) is a chitin synthesis inhibitor widely used against forest insect pests in Algeria. Prior to implementation of these products as chemical agents for mosquito control, knowledge on their potential effects on non-target organisms and its behaviour in water are needed. Therefore, the present study was focused on DFB and aimed to use an HPLC procedure developed previously in order to obtain information on its degradation in freshwater and its bioconcentration in adult females of the fish Gambusia affinis (Cyprinodondiformes, Poeciliidae), which is one of the best candidates fo r biological control programs against mosquitoes. The adult females were exposed to dimilin ® (initial concentration 312 ng a.i./ml) for 28 days and residues analysis determined at different exposure times (0, 7, 14, 21 and 28 days). The concentration of DFB in freshwater decreased with exposure time while the amount of residues detected at the surface of the fish body increased progressively to reach a maximum at day 14 (162.7± 14.0 ng/fish) and declined thereafter during the exposure period. In addition, DFB incorporation into body increased with decreasing DFB concentration in water at each exposure time. The following average distribution was noted at the end of experiment (28 days): about 33% of the applied concentration was detected on the surface of fish body and was recovered by simple rinsing, and about 67% was found inside the fish body. A degradation in water and surface of fish occurred starting day 14 during the experimental period. Thus, about 40% of the initial concentration was degraded in freshwater after 28 days. The results are discussed to develop a better understanding of the degradation of dimilin in water and their potential effect on non-target organisms for its application for controlling mosquito.

Running title: Dietary rescue of metabolic mutation and reproduction; To develop and reproduce, animals need long-chain Mono and PolyUnsaturated Fatty Acids (MUFAs; PUFAs). Although some UFAs can be synthesized by the organism, others must be provided by the diet. The gene desat1, involved in Drosophila melanogaster UFA metabolism, is necessary for both larval development and for adult sex pheromone communication. We first characterized desat1 expression in larval tissues. Then, we found that larvae in which desat1 expression was knocked down throughout development died during the larval stages when raised on standard food. By contrast pure MUFAs or PUFAs, but not saturated FAs, added to the larval diet, rescued animals to adulthood with the best effect being obtained with oleic acid (C18:1). Male and female mating behavior and fertility were affected very differently by preimaginal UFA-rich diet. Adult diet also strongly influenced several aspects of reproduction: flies raised on C18:1 rich diet showed increased mating performance compared to flies raised on standard adult diet. Therefore, both larval and adult desat1 expression control sex-specific mating signals. A similar nutrigenetics approach may be useful, in other metabolic mutants, to uncover cryptic effects otherwise masked by severe developmental defects.

International audience; Animals ubiquitously use chemical signals to communicate many aspects of their social life. These chemical signals often consist of environmental cues mixed with species-specific signals-pheromones-emitted by conspecifics. During their life, insects can use pheromones to aggregate, disperse, choose a mate, or find the most suitable food source on which to lay eggs. Before pupariation, larvae of several Drosophila species migrate to food sources depending on their composition and the presence of pheromones. Some pheromones derive from microbiota gut activity and these food-associated cues can enhance larval attraction or repulsion. To explore the mechanisms underlying the preference (attraction/repulsion) to these cues and clarify their effect, we manipulated factors potentially involved in larval response. In particular, we found that the (i) early exposure to conspecifics, (ii) genotype, and (iii) antibiotic treatment changed D. melanogaster larval behavior. Generally, larvae-tested either individually or in groups-strongly avoided food processed by other larvae. Compared to previous reports on larval attractive pheromones, our data suggest that such attractive effects are largely masked by food-associated compounds eliciting larval aversion. The antagonistic effect of attractive vs. aversive compounds could modulate larval choice of a pupariation site and impact the dispersion of individuals in nature.

1463-6395 10.1111/j.1463-6395.2008.00341.x; Willemart, R. H., Farine, J.-P. and Gnaspini, P. 2008. Sensory biology of Phalangida harvestmen (Arachnida, Opiliones): a review, with new morphological data on 18 species. 2014Acta Zoologica (Stockholm) 90: 2092013227 Phalangida includes three of the four suborders of Opiliones (Arachnida): Eupnoi, Dyspnoi and Laniatores. We review the literature on the sensory structures and capabilities of Phalangida, provide new morphological data for 18 species and discuss the 11 sensory structures that have been described in the group. Based on the published data encompassing both behaviour and morphology, three conclusions are apparent: (1) species of Phalangida appear to have limited abilities to detect stimuli at a distance; (2) close range olfaction probably helps to find foods with strong odours, but (3) they appear to be highly dependent on contact chemoreception to detect live prey, predators and mates. We also highlight the fact that legs I in the three suborders and pedipalps in Dyspnoi and Eupnoi are very important sensory appendages, thus legs II should not be called the 'sensory appendages' of harvestmen. In conclusion, we highlight the fact that the sensory capabilities, diet, prey capturing and handling ability, and foraging behaviour of species of Phalangida seem to be different from those of most other arachnids. Finally, we suggest future directions for studies in the field of the sensory system of the group.

In various animal species, male sexual dimorphic characters may be used during intrasexual contests as ornaments to attract females, or to hold them before, during, or after copulation. In the well-known harvestman, Phalangium opilio L., 1758, the behavioral functions of these male sexually dimorphic structures have never been studied in detail. Therefore, in addition to a morphometric study, 21 male contests and 43 sexual interactions were analyzed. Our observations revealed that during contests, the male cheliceral horns form a surface by which the contestants use to push each other face-to-face while rapidly tapping their long pedipalps against the pedipalps of the opponent, occasionally twisting the opponent's pedipalp. Scanning electron micrographs revealed contact mechanoreceptors on the pedipalp that would detect the intensity–frequency of contact with the contender's pedipalp. Larger males won almost all contests, whereas the loser rapidly fled. During sexual interactions, the longer pedipalps of the male held legs IV of the female, whereas males with shorter pedipalps held the female by legs III. No contact with the male pedipalps and chelicerae by the females was visible before, during, or after copulation. Soon after copulating, males typically bent over the female, positioning their cheliceral horns against the females's dorsum. Consequently, our data show that the cheliceral horns and the longer pedipalps of the male seem to play an important role, during both intersexual and intrasexual encountering. Resume : Chez de nombreuses especes animales, les ornementations sexuellement dimorphiques des mâles peuvent etre utilisees lors des combats rituels entre mâles ou comme signal afin d'attirer les femelles ou les retenir avant, pendant et apres l'accouplement. Chez l'opilion Phalangium opilio L., 1758, le role precis joue par ces structures n'a jamais ete mis en evidence. Au cours de ce travail, outre une etude morphometrique, nous avons analyse, grâce a des enregistrements video, 21 combats entre mâles et 43 accouplements. Nous avons pu montrer que, lors des combats, les mâles utilisent les cornes portees par les cheliceres pour se repousser lorsqu'ils sont face-a-face, tout en se tapant mutuellement a l'aide de leurs longs pedipalpes, voire en les enroulant avec ceux de l'adversaire. Des micrographies realisees au microscope electronique a balayage revelent l'existence de mecanorecepteurs sur les pedipalpes qui pourraient permettre au mâle de detecter la frequence et l'intensite des contacts des pedipalpes de son adversaire. Les mâles les plus grands gagnent presque tous les combats, le perdant fuyant rapidement. Au cours du comportement sexuel, les mâles a grands pedipalpes les utilisent pour agripper les pattes IV de la femelle, alors que les mâles a pedipalpes plus courts les retiennent par les pattes III. Il n'y a aucun contact tactile de la part des femelles avec les pedipalpes et les cheliceres des mâles avant, pendant et apres l'accouplement. Juste apres l'accouplement, le mâle s'appuie sur le dos de la femelle a l'aide des cornes de ses cheliceres. D'apres nos observations, il semble donc que les cheliceres et les longs pedipalpes des mâles jouent un role non negligeable lors des interactions intra- et inter-sexuelles chez cette espece.

The volatile constituents of the supposed defensive secretions of the glandular pouches of the adults of both sexes of the cockroach Therea petiveriana have been shown to contain N-3-methylbutylacetamide (MBA) and N-3-methylbutylpropanamide (MBP), which represented 60% of the volatile fraction. The other 40% included acidic, aromatic, and aldehydic compounds. Behavioral experiments demonstrated that the secretion acts as an alarm pheromone for adults.

Cockroaches are species that live at night and shelter in places that provide a suitable microclimate and allow them to have easy access to food. The inventory of African species is far from complete. In North Africa, little research has been conducted on wildlife Orthopteroid and more particularly on the Dictyoptera. To identify different species of cockroaches existing forest in northeastern Algeria, we made an inventory of species that live in various areas: cork oak forests [cork forests of El-Kala National Park (Tarf), of Edough (Annaba) and Souk-Ahras], eucalyptus forests (Annaba). Four species of cockroaches were collected from different sites: Loboptera decipiens, Loboptera angulata, Ectobius kervillei and some yet unidentified specimens Ectobius. All these insects are present in the litter, mainly from February to June, and their numbers are fluctuating. More than 2000 individuals of all stages were captured including 86% of the genus Loboptera and 14% of such Ectobius. Keywords: Forest Cockroaches, Inventory, Algerian Forests, Loboptera, EctobiusRésultats préliminaires d’un inventaire des Blattes forestières: Décomposeurs de la litière des forêts du Nord Est AlgérienLes blattes sont des insectes nocturnes s’abritant dans les endroits qui leur fournissent un microclimat convenable et qui leur permettent d'avoir un accès facile à la nourriture. L’inventaire des espèces africaines est loin d’être complet. En Afrique du Nord, peu de recherches ont été effectuées sur la faune des Orthoptéroïdes et plus particulièrement sur les Dictyoptères. Afin de recenser les différentes espèces de blattes forestières existant dans le Nord Est Algérien, nous avons réalisé un inventaire des espèces qui vivent dans différentes zones : forêts de chêne-liège [subéraies du Parc National d’El-Kala (Tarf), de l’Edough (Annaba) et de Souk-Ahras], forêts d’eucalyptus (Annaba). Quatre espèces de blattes ont été récoltées dans les sites prospectés: Loboptera decipiens, Loboptera angulata, Ectobius kervillei et quelques spécimens d’Ectobius non identifiés pour l’instant. Tous ces insectes sont présents dans la litière, principalement de Février à Juin, et leurs effectifs sont fluctuants. Plus de 2000 individus de tous stades ont été capturés parmi lesquels 86% sont du genre Loboptera et 14% du genre Ectobius. Mots clés : Inventaire, Forêts Algériennes, Blattes forestières, Loboptera, Ectobiu, Hamamböceği, gece ortaya çıkan ve uygun mikroiklim sağlayan ve yiyeceğe kolay erişim sağlayan yerlerde barınan bir türdür. Afrika türlerinin envanteri henüz tamamlanmamıştır. Kuzey Afrika’da, çiğneyici ağız tipi olan Orthopteroid’ler ve özellikle de Dictyoptera’nın yaban hayatı hakkında çok az araştırma yapılmıştır. Kuzeydoğu Cezayir’deki ormanda yaşayan farklı hamamböceği türlerini belirlemek amacıyla, mantar meşesi ormanları [El-Kala Milli Parkı mantar meşesi ormanları (Tarf, Edough mantar meşesi ormanları (ANnaba) ve Souk-Ahras ormanları], ökaliptüs ormanları (Annaba) olmak üzere farklı alanlarda yaşayan türlerin bir envanterini çıkardık. Farklı alanlardan dört hamamböceği türü toplandı: Loboptera decipiens, Loboptera angulata, Ectobius kervillei ve henüz tespit edilmemiş olan bazı Ectobius örnekleri. Tüm bu böcekler, ağırlıklı olarak Şubat ve Haziran arasında ölü örtüde bulunmaktadır ve sayıları ise değişmektedir. Loboptera cinsinden %86 ve Ectobius’tan %14 olmak üzere tüm evrelerden 2000’den fazla birey toplanmıştır.Anahtar kelimeler: Envanter, Cezayirli Ormanlar, orman Hamamböcekleri, Loboptera, Ectobius

Insects use chemosensory cues to feed and mate. In Drosophila , the effect of pheromones has been extensively investigated in adults, but rarely in larvae. The colonization of natural food sources by Drosophila buzzatii and Drosophila simulans species may depend on species-specific chemical cues left in the food by larvae and adults. We identified such chemicals in both species and measured their influence on larval food preference and puparation behaviour. We also tested compounds that varied between these species: (i) two larval volatile compounds: hydroxy-3-butanone-2 and phenol (predominant in D. simulans and D. buzzatii , respectively), and (ii) adult cuticular hydrocarbons (CHs). Drosophila buzzatii larvae were rapidly attracted to non-CH adult conspecific cues, whereas D. simulans larvae were strongly repulsed by CHs of the two species and also by phenol. Larval cues from both species generally reduced larval attraction and pupariation on food, which was generally—but not always—low, and rarely reflected larval response. As these larval and adult pheromones specifically influence larval food search and the choice of a pupariation site, they may greatly affect the dispersion and survival of Drosophila species in nature.

Trail-following bioassays show that trails of the two subterranean termites, Reticulitermes lucifugus grassei and R. santonensis, which are sympatric in some areas of southwestern France, are not species specific. Even when tested just above threshold level, trails from pentane extracts of whole workers of R. santonensis are always preferred by both species. If the R. santonensis extract is progressively diluted, the preference is lost. In purified extracts of workers of R. lucifugus grassei that elicited a trail-following response, only one compound is active. It was identified by GC-MS as the same major compound of the trail-following pheromone of R. santonensis: (Z,Z,E)-3,6,8-dodecatrien-1-ol (DTE-OH). The threshold concentration of activity of synthetic DTE-OH was determined to be 10−3 ng/cm of trail; optimal activity was obtained at 10−2 ng/cm of trail. The increase of trail-following activity of worker extracts of R. lucifugus grassei after hydrolysis by potassium hydroxide suggests that DTE-OH also is bound to other components in sternal gland secretions. DTE-OH was also identified in alates of R. lucifugus grassei, suggesting that the compound functions both as a trail-following and a sex pheromone, as has been shown to be the case in R. santonensis. This demonstrates the high economy developed by termites in their strategies of chemical communication.

The sexual behavior of males and females ofEurycotis floridana was investigated and the various associated behavioral sequences are described. Olfactometer data proved that the male produces a volatile sex pheromone attractive at a distance to conspecific females. The male initiates courtship behavior by exposing the glandular areas on the anterior parts of abdominal tergites 2, 7, and 8. This male calling behavior was observed throughout the day. The males can mate when 8 days old, whereas virgin females are sexually receptive 18 days after becoming adults. Once attracted near the male, the female opens her genital atrium and climbs on the back of the male, where she feeds on the glandular secretions that oozed around a little tuft of setae on the first tergite. These setae are mechanoreceptors and they are stimulated when licked by the females, which informs the male that she is in a proper position for copulation.

Hamambocegi, gece ortaya cikan ve uygun mikroiklim saglayan ve yiyecege kolay erisim saglayan yerlerde barinan bir turdur. Afrika turlerinin envanteri henuz tamamlanmamistir. Kuzey Afrika’da, cigneyici agiz tipi olan Orthopteroid’ler ve ozellikle de Dictyoptera’nin yaban hayati hakkinda cok az arastirma yapilmistir. Kuzeydogu Cezayir’deki ormanda yasayan farkli hamambocegi turlerini belirlemek amaciyla, mantar mesesi ormanlari [El-Kala Milli Parki mantar mesesi ormanlari (Tarf, Edough mantar mesesi ormanlari (ANnaba) ve Souk-Ahras ormanlari], okaliptus ormanlari (Annaba) olmak uzere farkli alanlarda yasayan turlerin bir envanterini cikardik. Farkli alanlardan dort hamambocegi turu toplandi: Loboptera decipiens, Loboptera angulata, Ectobius kervillei ve henuz tespit edilmemis olan bazi Ectobius ornekleri. Tum bu bocekler, agirlikli olarak Subat ve Haziran arasinda olu ortude bulunmaktadir ve sayilari ise degismektedir. Loboptera cinsinden %86 ve Ectobius’tan %14 olmak uzere tum evrelerden 2000’den fazla birey toplanmistir. Anahtar kelimeler: Envanter, Cezayirli Ormanlar, orman Hamambocekleri, Loboptera, Ectobius

International audience; Recognition of conspecifics and mates is based on a variety of sensory cues that are specific to the species, sex and social status of each individual. The courtship and mating activity of Drosophila melanogaster flies is thought to depend on the olfactory perception of a male-specific volatile pheromone, cis-vaccenyl acetate (cVA), and the gustatory perception of cuticular hydrocarbons (CHs), some of which are sexually dimorphic. Using two complementary sampling methods (headspace Solid Phase Micro-Extraction [SPME] and solvent extraction) coupled with GC-MS analysis, we measured the dispersion of pheromonal CHs in the air and on the substrate around the fly. We also followed the variations in CHs that were induced by social and sexual interactions. We found that all CHs present on the fly body were deposited as a thin layer on the substrate, whereas only a few of these molecules were also detected in the air. Moreover, social experience during early adult development and in mature flies strongly affected male volatile CHs but not cVA, whereas sexual interaction only had a moderate influence on dispersed CHs. Our study suggests that, in addition to their role as contact cues, CHs can influence fly behavior at a distance and that volatile, deposited and body pheromonal CHs participate in a three-step recognition of the chemical identity and social status of insects.

Poster

Summary Nymphs and adult females ofBlatta orientalis and nymphs ofEurycotis floridana produce a proteinaceous sticky secretion which accumulates on the last abdominal tergites. The proteic patterns do not differ between individuals of the same species. HPLC analyses show that all the common amino acids are found in both species, aspartic and glutamic acids representing 24 to 37% of the total amount of amino acids. InB. orientalis, glutamic acid is the more abundant amino acid whereas inE. floridana it is the aspartic acid. The secretion appears and accumulates rapidly on isolated insects. Behavioural assays revealed that these secretions have a defensive role.

International audience; Many animals attract mating partners through the release of volatile sex pheromones, which can convey information on the species, gender and receptivity of the sender to induce innate courtship and mating behaviours by the receiver. Male Drosophila melanogaster fruitflies display stereotyped reproductive behaviours towards females, and these behaviours are controlled by the neural circuitry expressing male-specific isoforms of the transcription factor Fruitless (FRU(M)). However, the volatile pheromone ligands, receptors and olfactory sensory neurons (OSNs) that promote male courtship have not been identified in this important model organism. Here we describe a novel courtship function of Ionotropic receptor 84a (IR84a), which is a member of the chemosensory ionotropic glutamate receptor family, in a previously uncharacterized population of FRU(M)-positive OSNs. IR84a-expressing neurons are activated not by fly-derived chemicals but by the aromatic odours phenylacetic acid and phenylacetaldehyde, which are widely found in fruit and other plant tissues that serve as food sources and oviposition sites for drosophilid flies. Mutation of Ir84a abolishes both odour-evoked and spontaneous electrophysiological activity in these neurons and markedly reduces male courtship behaviour. Conversely, male courtship is increased--in an IR84a-dependent manner--in the presence of phenylacetic acid but not in the presence of another fruit odour that does not activate IR84a. Interneurons downstream of IR84a-expressing OSNs innervate a pheromone-processing centre in the brain. Whereas IR84a orthologues and phenylacetic-acid-responsive neurons are present in diverse drosophilid species, IR84a is absent from insects that rely on long-range sex pheromones. Our results suggest a model in which IR84a couples food presence to the activation of the fru(M) courtship circuitry in fruitflies. These findings reveal an unusual but effective evolutionary solution to coordinate feeding and oviposition site selection with reproductive behaviours through a specific sensory pathway.

WOS:000296521400044; International audience; Fatty-acids (FAs) are required in the diet of many animals throughout their life. However, the mechanisms involved in the perception of and preferences for dietary saturated and unsaturated FAs (SFAs and UFAs, respectively) remain poorly explored, especially in insects. Using the model species Drosophila melanogaster, we measured the responses of wild-type larvae and adults to pure SFAs (14, 16, and 18 carbons) and UFAs (C18 with 1, 2, or 3 double-bonds). Individual and group behavioral tests revealed different preferences in larvae and adults. Larvae preferred UFAs whereas SFAs tended to induce both a strong aversion and a persistent aggregation behavior. Adults generally preferred SFAs, and laid more eggs and had a longer life span when ingesting these substances as compared to UFAs. Our data suggest that insects can discriminate long-chain dietary FAs. The developmental change in preference shown by this species might reflect functional variation in use of FAs or stage-specific nutritional requirements, and may be fundamental for insect use of these major dietary components.