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Colorado potato beetle [Leptinotarsa decemlineata (Say); Coleoptera: Chrysomelidae] is a widespread key pest of potatoes and other solanaceous crops of the temperate Northern Hemisphere. Its evolution of multiple pesticide resistance is a continuing threat if chemical control is relied upon for pest management. An integrated approach including semiochemicals and other non-pesticidal tactics is essential to sustainable management. In addition to the known volatile aggregation pheromone produced by male adult beetles that is attractive to both females and males, there is a yet-unidentified female-produced sex pheromone. Using caged 'bait plants' in the field in Maryland, USA, we tested the attraction of male and female beetles to groups of male-only, female-only, larvae, and uninfested bait plants.Results of five field experiments demonstrate that the female-produced sex pheromone is attractive to male beetles, whereas the male-produced pheromone is attractive to both females and males. Male attraction increased with higher densities of females on bait plants, but female attraction did not change with female density on bait plants.This is the first study to demonstrate male attraction to the female sex pheromone in the field, and to our knowledge, the first to demonstrate a beetle species using bidirectional communication between males and females. Use of semiochemicals for monitoring and management of Colorado potato beetle should consider male-, female-, as well as plant-produced volatiles as important tools for pest manipulation in potato integrated pest management. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

Background The potato tuber moth, Phthorimaea operculella is a key pest of potato and tobacco in China. We compared the sex pheromone titers released by P. operculella female, and the electroantennogram (EAG) responses of male antennae to pheromone compounds under laboratory conditions. Then, the optimal sex pheromone ratio was screened in the field. Results The P. operculella sex pheromone feeding on potato or tobacco was extracted by solvent-extraction method. Main sex pheromone compounds including E4, Z7-13: AC (PTM1) and E4, Z7, Z10-13: AC (PTM2) were found in gland. The titer and relative ratio of P. operculella sex pheromone compounds secreted by female adult moths differ between host populations, while the relative EAG responses trend of P. operculella males to the pheromone components were the same when directly stimulated. In field trials, PTM1:PTM2=8:1-4:1 and PTM1:PTM2=1:4-1:7 was the most attractive ratio to P. operculella males in tobacco and potato fields, respectively. During 2019-2020, after 8 weeks of mass trapping for each year, the sex pheromone could reduce the population of P. operculella in the potato and tobacco fields. Conclusions In this study, fixed property and quantity analyzing methods were adopted to compare sex pheromones from feeding on potato versus tobacco. EAG tests then were carried out on P. operculella males. Finally, we optimized the ratio of two sex pheromone compounds in potato and examined how this influenced field trapping. By further improving the parameters of sex pheromone application in the field, we demonstrate that deployment of sex pheromones can provide effective control of P. operculella. This article is protected by copyright. All rights reserved.

Ants use chemical signals to communicate for various purposes related to colony function. Social organization in the red imported fire ant, Solenopsis invicta, is determined by the Sb supergene, with colonies of the monogyne (single-queen) form lacking the element and colonies of the polygyne (multiple-queen) form possessing it. Polygyne workers accept new reproductive queens in their nest, but only those carrying Sb; young winged queens lacking this genetic element are executed as they mature sexually in their natal nest or as they attempt to enter a foreign nest to initiate reproduction after mating and shedding their wings. It has been suggested that queen supergene genotype status is signaled to workers by unsaturated cuticular hydrocarbons, while queen reproductive status is signaled by piperidines (venom alkaloids). We used high-throughput behavioral assays to study worker acceptance of paper dummies dosed with fractions of extracts of polygyne queens, or blends of synthetic counterparts of queen cuticular compounds. We show that the queen supergene pheromone comprises a blend of monoene and diene unsaturated hydrocarbons. Our assays also reveal that unsaturated hydrocarbons elicit discrimination by polygyne workers only when associated with additional compounds that signal queen fertility. This synergistic effect was obtained with a polar fraction of queen extracts, but not by the piperidine alkaloids, suggesting that the chemical(s) indicating queen reproductive status are compounds more polar than cuticular hydrocarbons but are not the piperidine alkaloids. Our results advance understanding of the role of chemical signaling that is central to the regulation of social organization in an important invasive pest and model ant species.

Developmental diapause is a widespread strategy for animals to survive seasonal starvation and environmental harshness. Diapaused animals often ration body fat to generate a basal level of energy for enduring survival. How diapause and fat rationing are coupled, however, is poorly understood. The nematode Caenorhabditis elegans excretes pheromones to the environment to induce a diapause form called dauer larva. Through saturated forward genetic screens and CRISPR knockout, we found that dauer pheromones feed back to repress the transcription of ACOX-3, MAOC-1, DHS-28, DAF-22 (peroxisomal β-oxidation enzymes dually involved in pheromone synthesis and fat burning), ALH-4 (aldehyde dehydrogenase for pheromone synthesis), PRX-10 and PRX-11 (peroxisome assembly and proliferation factors). Dysfunction of these pheromone enzymes and factors relieves the repression. Surprisingly, transcription is repressed not by pheromones excreted but by pheromones endogenous to each animal. The endogenous pheromones regulate the nuclear translocation of HNF4α family nuclear receptor NHR-79 and its co-receptor NHR-49, and, repress transcription through the two receptors. The feedback repression maintains pheromone homeostasis, increases fat storage, decreases fat burning, and prolongs dauer lifespan. Thus, the exocrine dauer pheromones possess an unexpected endocrine function to mediate a peroxisome-nucleus crosstalk, coupling dauer diapause to fat rationing.

Chemical signals play indispensable roles in the communication and social behavior of many organisms. Pheromones are a class of chemical signals identified initially in insects. Later, it became evident that diverse animals secrete pheromones in their body exudates and from exocrine glands and use them for social communication. The pig is a vital food animal in which steroid pheromones have been identified and their behavioral effects known since the 1960s. More recently, non-steroidal pheromones have been identified. To date, studies have reported various pheromone sources in boars (saliva, urine, and glandular secretions) and sows (urine, mammary gland secretions, and feces) and pheromone-mediated behavioral consequences are evidenced. These include the boar effect on puberty onset and subsequent estrous behaviors as well as agonistic and avoidance behaviors. Recent research has facilitated the development and evaluation of pheromone-based applications and products to improve the welfare and reproductive performance of pigs. This review aims to summarize the current knowledge of pig pheromones, and their implications in behaviors.

The fall armyworm Spodoptera frugiperda is a worldwide serious agricultural pest, and recently invades in South China. Sex pheromone can be employed to monitor its population dynamics accurately in the field. However, the pheromone components previously reported by testing different geographic populations and strains are not consistent. On the basis of confirming that the S. frugiperda population from Yunnan province belonged to the corn strain, we analyzed the potential sex pheromone components in the pheromone gland extracts of females using the gas chromatography coupled with electroantennographic detection (GC-EAD), gas chromatography coupled with mass spectrometry (GC-MS) and electroantennography (EAG). The results show that (Z)-9-tetradecenal acetate (Z9-14:Ac), (Z)-11-hexadecenyl acetate (Z11-16:Ac), (Z)-7-dodecenyl acetate (Z7-12:Ac) or (E)-7-dodecenyl acetate (E7-12:Ac) with a ratio of 100: 15.8: 3.9 induced EAD responses to varying degree: Z9-14:Ac elicited a strong EAD response, Z7-12:Ac or E7-12:Ac elicited a small but clear EAD response, while Z11-16:Ac elicited a weak EAD response. The further single sensillum recording (SSR) showed that Z9-14:Ac and Z7-12:Ac induced dose-dependent activities in two types (A and B) of sensilla in male antennae, respectively, while the sensilla in response to E7-12:Ac and Z11-16:Ac was not recorded. Finally, wind tunnel tests reveal that Z9-14:Ac and Z7-12:Ac are two principal sex pheromone components of the tested population. This article is protected by copyright. All rights reserved.

The indiscriminate use of pesticides leads to irreparable damage to the ecosystem, which motivates for sustainable alternatives like pheromone-assisted pest management. The tomato pinworm Tuta absoluta is a major threat to tomato cultivation. Moreover, its green management technology uses a pheromone trap that has a short field life. To overcome this problem, a pheromone composite with graphene oxide (GO) and amine-modified graphene oxide (AGO) that can extend the diffusion path has been developed. The composite stimulates an effective electrophysiological response in the antenna, which results in trapping of a significantly higher number of insects as compared to the commercial septa, thus qualifying it for field evaluation. Compared to AGO, the GO composite has pheromones assembled into a multilayer, which increases the pheromone diffusion path. This in turn resulted in the extension of the pheromone life that proportionally increased the pest trapped. This technique will be beneficial to farmers as they have longer field efficacy to keep the pest damage low in an environmentally friendly manner.

Responses to sex pheromones are commonly antagonized by pheromone components of closely related species. Pheromone antagonism has not been widely explored for phylogenetically distant species that have completely different pheromone components. Yet, pheromone components of sympatrically occurring species may also interfere with each other even if these species are distantly related. Here, the effects of heterospecific pheromones on electrophysiology (electroantennogram, EAG) and behavioral responses were tested on the diamondback moth Plutella xyloslella (Plutellidae) and two sympatric noctuid moth species, Spodoptera litura and Spodoptera exigua, whose larvae also feed on Brassica crops.The sex pheromone blend of P. xyloslella, and its components, did not elicit EAG responses in males of the two noctuid species, while sex pheromone components of the noctuid moths elicited significant EAG responses in P. xyloslella males. In wind tunnel bioassays, both (Z, E)-9, 12-tetradecadienyl acetate (ZE-9,12-14:OAc) and (Z, E)-9, 11-tetradecadienyl acetate (ZE-9,11-14:OAc), sex pheromone components from the noctuid moths, inhibited the upwind flight behavior of P. xyloslella males toward an intraspecific pheromone odor source. In Brassica fields, sex pheromone lures of P. xyloslella did not influence trap catches of the noctuid moths, while P. xyloslella pheromone lures baited with either ZE-9,11-14:OAc or ZE-9,12-14:OAc decreased trap catches of P. xyloslella males in a dose-dependent manner. Trap catches of P. xylostella males were also affected by the proximity of ZE-9,11-14:OAc or ZE-9,12-14:OAc to P. xylostella lures.The uni-directional pheromone antagonism by ZE-9,11-14:OAc and ZE-9,12-14:OAc suggests innovative semiochemical-based strategies for the management of P. xyloslella and other economically important pests in Brassica fields. © 2021 Society of Chemical Industry.

Mammals have microbes resident in their reproductive tract, some of which can be pathogenic while others may play a role in protecting the tract from infection. Volatile compounds play a role as sex pheromones that attract males for coitus during female estrus or heat. It is likely that these compounds themselves are secondary metabolites of bacterial flora resident in the vagina. In order to substantiate this hypothesis, bacteria were isolated from cervico-vaginal mucus (CVM) of buffalo during various phases of the estrous cycle and identified, using morphological, biochemical and molecular characteristics, as Bacillus during preestrus and diestrus, and as Staphylococcus during all three phases of the estrous cycle. Populations of Staphylococcus differed between different phases of the estrous cycle, the predominant forms being S. warneri (BCVMPE1_1) during preestrus, S. pastueri (BCVME2) during estrus and S. epidermis (BCVMDE3) during diestrus. Mice were used as chemosensors to differentiate the estrus-specific S. pasteuri (BCVME2) from the others. Chemical analysis showed that S. pasteuri (BCVME2) produced acetic, propanoic, isobutyric, butyric, isovaleric and valeric acids. In addition, it was shown that S. pasteuri (BCVME2) volatiles influenced the sexual behaviors, flehmen and mounting, of the bull. Thus, S. pasteuri (BCVME2) is a potential source of vaginal pheromone(s) during estrus in buffalo.

Most experimental studies on sexual signal regulation via hormone manipulation have focused on male signals, yet female signals demonstrate substantial phenotypic variation and hormone-dependent expression. Female red-sided garter snakes (Thamnophis sirtalis parietalis) produce a skin-based sex pheromone used by males in mate selection. The principle female sex steroid, 17 β-estradiol, controls pheromone production in snakes, but studies manipulating female garter snakes have produced conflicting results, relied on behavioral tests with males in the laboratory, and did not quantify pheromone expression. Because aromatase is the terminal enzyme in estradiol biosynthesis, we hypothesized that female garter snakes rely on aromatase to ultimately control pheromone production during the annual cycle of this species. To test this, we used a known pharmacological inhibitor of aromatase, fadrozole (FAD). Wild-caught female garter snakes were chronically treated via subcutaneous injections of either FAD (1.0 mg kg-1 ) or saline (control) for six months in the laboratory during the active period of the annual cycle then hibernated. In two separate field bioassays the next spring at the den site, FAD females received approximately 50% less courtship from wild, sexually active male garter snakes compared to SHAM females. Pheromone analysis revealed that four of the largest, unsaturated methyl ketones were specifically downregulated in FAD females, indicating that aromatase action is a crucial, permissive step in the maintenance of female attractivity.

Objectives Transport can be a stressful experience for domestic cats. The objective of this study was to evaluate the effect of a new synthetic feline facial pheromone product on relieving stress in domestic cats during short-distance transport. Methods A randomised, blinded, placebo-controlled pilot study was conducted. Prior to baseline screening, cat owners were trained via online meetings in the assessment of stress-related behaviours and overall stress visual analogue scoring. All assessments were completed 30 mins after the start of transport. A total of 150 domestic cats exhibiting stress-related behaviours during baseline screening were recruited and randomly assigned to either the treatment group (n = 75) or the placebo group (n = 75). For the placebo-controlled intervention, the product and placebo, which were identical in appearance, were provided to the treatment and placebo groups, respectively. Fifteen minutes after spraying the carriers with the product or placebo, cat owners were required to take their cat out and complete the same assessments (baseline screening). Results After the intervention, the performance of the stress-related behaviours curling, lack of motion and meowing during transport outside the home was significantly reduced in the treatment group compared with the placebo group ( P 2.94 cm, cats in the treatment group had significantly lower post-intervention stress VAS scores compared with those in the placebo group ( P Conclusions and relevance A synthetic feline facial pheromone product can alleviate short-distance transport-related stress in domestic cats with higher stress scores. This finding will benefit domestic cats during transport outside of the home.

Semiochemical background in the environment can influence insect orientation to release points of the same or different semiochemicals. endo-Brevicomin is a pheromone component of the tree-killing bark beetle Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae) that has a biphasic dose–response curve, enhancing attraction at low release rates but reducing attraction at high rates. We investigated the effect of artificial manipulation of background levels of endo-brevicomin on D. frontalis responses to sources of aggregation attractant in the field. Traps baited with the aggregation pheromone component frontalin and the host odor alpha-pinene were deployed either with or without a background of endo-brevicomin produced by three surrounding dispensers of this semiochemical each located 20 m away. Two tested levels of endo-brevicomin background caused catches to increase by an order of magnitude above those in the absence of background. Presence of background also altered the beetles' biphasic dose–response when endo-brevicomin dispensers were added to traps. Background reduced or concealed attraction-enhancement otherwise observed for low-release dispensers added to traps, and it decreased the release rate necessary to produce reductions in catches. We propose that spatial variability in abundance of natural, background sources of endo-brevicomin in the environment (i.e., infested trees) is a cause of the observed variability in effects of endo-brevicomin dispensers on southern pine beetle behavior in the field. Furthermore, our results illustrate the potential complexity of the density-dependent effects of biphasic pheromone components on bark beetle mass attack and colonization behavior.

Odorant-binding proteins (OBPs) of vertebrates belong to the lipocalin superfamily and perform a dual function: solubilizing and ferrying volatile pheromones to the olfactory receptors, and complexing the same molecules in specialized glands and assisting their release into the environment. Within vertebrates, to date they have been reported only in mammals, apart from two studies on amphibians. Based on the small number of OBPs expressed in each species, on their sites of production outside the olfactory area and their presence in biological fluids known to be pheromone carriers, such as urine, saliva and sexual secretions, we conclude that OBPs of mammals are specifically dedicated to pheromonal communication. This assumption is further supported by the observation that some OBPs present in biological secretions are endowed with their own pheromonal activity, adding renewed interest to these proteins. Another novel piece of evidence is the recent discovery that glycosylation and phosphorylation can modulate the binding activity of these proteins, improving their affinity to pheromones and narrowing their specificity. A comparison with insects and other arthropods shows a completely different scenario. While mammalian OBPs are specifically tuned to pheromones, those of insects, which are completely different in sequence and structure, include carriers for general odorants in addition to those dedicated to pheromones. Additionally, whereas mammals adopted a single family of carrier proteins for chemical communication, insects and other arthropods are endowed with several families of semiochemical-binding proteins. Here, we review the literature on the structural and functional properties of vertebrate OBPs, summarize the most interesting new findings and suggest possible exciting future developments.

Loxosceles reclusa, or brown recluse spider, is a harmful household spider whose habitat extends throughout the Midwest in the USA and other regions in the world. The pheromones and other biomolecules that facilitate signaling for brown recluses and other spider species are poorly understood. A rapid and sensitive method is needed to analyze airborne spider signaling biomolecules to better understand the structure and function of these biochemicals in order to control the population of the spiders. In this study, we developed a novel headspace solid-phase microextraction (HS-SPME)-GC/MS method to analyze potential pheromones and biomolecules emitted by the brown recluse spider. The method is highly selective and sensitive for biomolecule identification and quantification from a single live spider. Using this novel non-destructive HS-SPME-GC/MS technique, we identified 11 airborne biomolecules, including 4-methylquinazoline, dimethyl sulfone, 2-methylpropanoic acid, butanoic acid, hexanal, 3-methylbutanoic acid, 2-methylbutanoic acid, 2,4-dimethylbenzaldehyde, 2-phenoxyethanol, and citral (contains both isomers of neral and geranial). Some of these airborne biomolecules were also reported as semiochemicals associated with biological functions of other spiders and insects. The method was also applied to study the airborne biochemicals of Plectreurys tristis, another primitive hunting spider with a poor web, enabling quantitation of the same compounds and demonstrating a difference in signaling molecule concentrations between the two species. This method has potential application in the study of pheromones and biological signaling in other species, which allows for the possibility of utilizing attractant or deterrent functions to limit household populations of harmful species.

Four species of Limonius wireworms (Coleoptera: Elateridae), L. californicus, L. canus, L. infuscatus and L. agonus, are serious crop pests in North America. Limoniic acid, (E)-4-ethyloct-4-enoic acid, has been reported as a sex pheromone component of female L. californicus and L. canus, and a sex attractant for male L. infuscatus. In the same study, both limoniic acid and the analog (E)-5-ethyloct-4-enoic acid were highly attractive in field experiments. Moreover, six carboxylic acids in headspace volatiles of Limonius females elicited responses from male antennae but were not tested for behavioral activity. Here, we report trap catch data of Limonius spp. obtained in field experiments at 27 sites across North America. All four Limonius species were attracted to limoniic acid and to the analog but not to the carboxylic acids. Adding these carboxylic acids to limoniic acid, or to the analog, reduced its attractiveness. In dose–response studies, trap lures containing 0.4 mg or 4 mg of limoniic acid afforded large captures of L. californicus and L. infuscatus. Neither limoniic acid nor the analog were deterrent to other elaterid pest species. The broad attractiveness of limoniic acid to Limonius spp., and its non-deterrent effect on heterogeners, may facilitate the development of generic pheromone-based monitoring and management tools for multiple click beetle species.

Melanotus communis Gyllenhal (Coleoptera: Elateridae) larvae are a common soil-dwelling pest of many crops, including sweet potato, grains, and tobacco. Although many studies have focused on the larval stage of this pest, the seasonal activity and ecology of the adults (click beetles) are not well understood. The overarching goal of this study was to relate M. communis adult activity to host crops in the North Carolina row-crop agroecosystem. To do this, we conducted a two-year study documenting male M. communis activity, using a recently identified sex attractant pheromone, 13-tetradecenyl acetate. This project was divided into two parts: 1) a pheromone assessment study testing the efficacy and specificity of 13-tetradecenyl acetate, and two analogs, 13-tetradecenyl butyrate and 13-tetradecenyl hexanoate, and 2) a landscape survey using traps baited with 13-tetradecenyl acetate. Results of the efficacy study showed that 13-tetradecenyl acetate was the most effective M. communis lure when compared to non-baited control traps or traps baited with the two homologs. The landscape study documented a strong association between M. communis catch and the adjacent crop type. We found that adult M. communis abundance was greatest near corn, followed by sweet potato, and then cotton. Analysis of activity over time found that the peak activity occurred during July. Overall, this project demonstrates the usefulness of pheromone-baited traps in providing new information about M. communis activity.

Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (DFB), is the most damaging insect pest of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, in western North America. Individual high-value trees and stands can be protected during DFB outbreaks using the beetle's anti-aggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), which is available in several commercial formulations. However, other methylcyclohexanones similar in molecular structure to MCH have been shown to repel bees from agricultural areas. In forest systems, wild bees (Hymenoptera: Apiformes) provide essential pollination services to many forb and shrub species. Therefore, it is important to determine whether resident wild bee communities are affected in forests treated with MCH. To address this, the bee community was sampled within experimental sites located in Idaho and Montana, USA in 2016. At both sites, there was no significant difference in overall bee abundance, species richness, or diversity between MCH-treated plots and untreated control plots. Overall, these results indicate that treatment of Douglas-fir with MCH does not negatively impact the resident wild bee community.

Field experiments were carried out in the reclaimed land east of Cairo-Alexandria Desert Road, Village of Wardan, Giza Governorate, Egypt, to evaluate the impact of using nano-gels pheromone for the first time on the attraction of the RPW adults by pheromone traps compared to the control which is normal pheromone during two successive seasons in 2018 and 2019. Also, this study aimed to compare the efficacy of two types of trap, traditional trap (type 1) and dry funnel trap (type 2) in capturing of RPW adults. Results revealed that the nano gel pheromone traps attracted significantly more adults with an average of (4.26 and 3.56) adults/trap and total of (55.33 and 46.33) adults/trap compared to control with an average (2.69 and 2.46) and total of (35.00 and 32.00) adults/trap for the two seasons 2018 and 2019 respectively. Results indicated that the use of nano gel pheromone for the first time in field improved the trap catchability to RPW adults by 22.51 and 18.30% of total number of RPW adults captured throw out the two successive seasons respectively. In addition, there was no significant difference between the total numbers of RPW adults collected by the two tested type of traps over the two successive seasons. Furthermore, the sex ratio between males and females of total collected RPW adults found to be1: 1.43 and 1: 1.94 at 2018 and 2019 respectively.

Paralobesia viteana (Clemens), grape berry moth, is a major pest of grapes in Eastern North America. There is substantial regional variation in the response of male P. viteana to sex pheromone-baited monitoring traps in Michigan vineyards. Males are readily captured in traps in the southwest region, whereas in the northwest very few males are captured, despite larval infestation in grapes in both regions. Y-tube olfactometers and field experiments determined the response of male moths from northern and southern populations to the pheromone blend used in monitoring lures and to females from both regions. In Y-tube choice tests, males responded similarly to the standard pheromone blend, and males did not preferentially choose females from either region. In field trials, traps baited with unmated females were deployed to test the preference of resident males for females from the two regions and for standard pheromone lures. In southwest Michigan vineyards, significantly more males were caught in traps with a 1.0-µg standard pheromone lure than in traps with captive females collected from vineyards in both regions or in traps with a blank lure control. A similar pattern of male captures among lure treatments was observed in northwest vineyards, although many fewer males were trapped and differences among treatments were not significant. We conclude that the observed regional differences in male response to pheromone traps are not caused by variation in pheromone-mediated behavioral responses, suggesting that other biotic and/or abiotic differences determine the regional variation in captures of this species.

The sex pheromone composition of alfalfa plant bugs, Adelphocoris lineolatus (Goeze), from Central Europe was investigated to test the hypothesis that insect species across a wide geographical area can vary in pheromone composition. Potential interactions between the pheromone and a known attractant, (E)-cinnamaldehyde, were also assessed. Coupled gas chromatography-electroantennography (GC-EAG) using male antennae and volatile extracts collected from females, previously shown to attract males in field experiments, revealed the presence of three physiologically active compounds. These were identified by coupled GC/mass spectrometry (GC/MS) and peak enhancement as hexyl butyrate, (E)-2-hexenyl butyrate and (E)-4-oxo-2-hexenal. A ternary blend of these compounds in a 5.4:9.0:1.0 ratio attracted male A. lineolatus in field trials in Hungary. Omission of either (E)-2-hexenyl-butyrate or (E)-4-oxo-2-hexenal from the ternary blend or substitution of (E)-4-oxo-2-hexenal by (E)-2-hexenal resulted in loss of activity. These results indicate that this Central European population is similar in pheromone composition to that previously reported for an East Asian population. Interestingly, another EAG-active compound, 1-hexanol, was also present in female extract. When 1-hexanol was tested in combination with the ternary pheromone blend, male catches were reduced. This compound showed a dose-response effect with small doses showing a strong behavioral effect, suggesting that 1-hexanol may act as a sex pheromone antagonist in A. lineolatus. Furthermore, when (E)-cinnamaldehyde was field tested in combination with the sex pheromone, there was no increase in male catch, but the combination attracted both males and females. Prospects for practical application are discussed.

Anagrus atomus (L.) is an egg parasitoid used for the biological control of Empoasca vitis (Goethe) in vineyards. Sex pheromones play a crucial role in mate finding process of several parasitoid species and could be used for monitoring under field conditions. We carried out lab and field studies aiming at assessing the existence and identity of a possible A. atomus sex pheromone. We found that males were significantly attracted by virgin female independently from female age. Males were not attracted from individuals of the same sex but they were attracted by crude extract of an unmated female and its polar fraction. Eugenol (4-allyl-2-methoxyphenol) was identified as the attractive substance and proved to be attractive not only in the olfactometer but also in another laboratory bioassay and under field conditions. Attraction of males, but not females, confirms that this is not an aggregation pheromone. This is the first sex-pheromone component identified in Mymaridae but more compounds could be involved in the mating behaviour of A. atomus. The utility of a sex pheromone in A. atomus is discussed in the context of fitness returns.

Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is a tropical mirid bug used as a biocontrol agent in protected crops, including tomatoes. Although N. tenuis predates important insect pests, especially whitefly, it also causes damage by feeding on tomato plants when prey populations decline, resulting in significant economic losses for growers. The pest is now established in some all-year-round tomato crops in Europe and control measures involve the application of pesticides which are incompatible with current IPM programs. As part of future IPM strategies, the pheromone of N. tenuis was investigated. Volatile collections were made from groups and individuals of mated and unmated, females and males. In analyses of these collections by gas chromatography coupled with electroantennographic (EAG) recording from antennae of male bugs, two EAG-active components were detected and identified as 1-octanol and octyl hexanoate. Unlike other mirids, both male and female N. tenuis produced the two compounds, before and after mating, and both sexes gave EAG responses to both compounds. Furthermore, only octyl hexanoate was detected in whole body solvent washes from both sexes. These compounds are not related to the derivatives of 3-hydroxybutyrate esters found as pheromone components in other members of the Bryocrinae sub-family, and the latter could not be detected in volatiles from N. tenuis and did not elicit EAG responses. Nevertheless, experiments carried out in commercial glasshouses showed that traps baited with a blend of the synthetic pheromone components caught essentially only male N. tenuis, and significantly more than traps baited with octyl hexanoate alone. The latter caught significantly more N. tenuis than unbaited traps which generally caught very few bugs. Traps at plant height caught more N. tenuis males than traps 1 m above or at the base of the plants. The trap catches provided an indication of population levels of N. tenuis and were greatly reduced following an application of insecticide.

Social behavior is one of the most fascinating and complex behaviors in humans and animals. A fundamental process of social behavior is communication among individuals. It relies on the capability of the nervous system to sense, process, and interpret various signals (e.g., pheromones) and respond with appropriate decisions and actions. Eusocial insects, including ants, some bees, some wasps, and termites, display intriguing cooperative social behavior. Recent advances in genetic and genomic studies have revealed key genes that are involved in pheromone synthesis, chemosensory perception, and physiological and behavioral responses to varied pheromones. In this review, we highlight the genes and pathways that regulate queen pheromone-mediated social communication, discuss the evolutionary changes in genetic systems, and outline prospects of functional studies in sociobiology.

The vaginal microbiota has been studied in animal reproduction and fertility, in particular little information of vaginal microbes in reference to bovine reproduction and pheromone production is known. The vaginal mucosa in healthy cow is colonized by an equilibrated and dynamic composition of aerobic, facultative anaerobic and obligate anaerobic microbes. Cervico-vaginal mucus (CVM) composition, viscosity and volume vary with the cyclicity and health status of the reproductive tract. In addition, CVM contains pheromones, volatile compounds, and proteins that attract males for coitus. Commensal microbiota plays a key role in protection of the genital tract from pathogenic microbes by competition effect. In the bovine species, the microbial composition, its abundance and diversity in the female gut, vagina, urine, saliva, and feces, and the associated chemical communication remains poorly documented. The impact of microbes in the reproductive tract of cow, buffalo and certain mammals are discussed in this review. Since the microbial population diversity of CVM is modified during estrus phase it presumes that it may have a role for pheromone production in conspecific. Herein, we would like to critically discuss the current state of knowledge on microbially produced signals in animals and the role of genital and CVM microbiota in estrous cycle and pregnancy.

The information that female insects perceive and use during oviposition site selection is complex and varies by species and ecological niche. Even in relatively unexploited niches, females interact directly and indirectly with conspecifics at oviposition sites. These interactions can take the form of host marking and re-assessment of prior oviposition sites during the decision-making process. Considerable research has focused on the niche breadth and host preference of the polyphagous invasive pest Drosophila suzukii Matsumura (Diptera: Drosophilidae), but little information exists on how conspecific signals modulate oviposition behavior. We investigated three layers of social information that female D. suzukii may use in oviposition site selection—(1) pre-existing egg density, (2) pre-existing larval occupation, and (3) host marking by adults. We found that the presence of larvae and host marking, but not egg density, influenced oviposition behavior and that the two factors interacted over time. Adult marking appeared to deter oviposition only in the presence of an unmarked substrate. These results are the first behavioral evidence for a host marking pheromone in a species of Drosophila. These findings may also help elucidate D. suzukii infestation and preference patterns within crop fields and natural areas.

Bark beetles (family: Curculionidae; subfamily: Scolytinae) in the Dendroctonus and Ips genera are the most destructive forest pests in the Northern hemisphere. They use cytochromes P450 (P450s) to detoxify tree-produced terpenes to produce pheromones, in de novo pheromone production and to oxidize odorants on antennae. Many Dendroctonus spp. use trans-verbenol as an aggregation pheromone, and it is formed from host-tree produced α-pinene hydroxylated by CYP6DE1 during larval stages, stored as verbenyl ester of fatty acids, and then released when the female begins feeding on a new host tree. Ips spp. hydroxylate de novo produced myrcene to form ipsdienol. Subsequent steps form the appropriate enantiomeric composition of ipsdienol and convert ipsdienol to ipsenol. In this article we review recent progress in elucidating the functions of P450s in Ips and Dendroctonus species and in doing so provide insights into the role of these enzymes in host phytochemical detoxification and pheromone production.

Background Excretory-secretory (ES) products are crucial in maintaining helminths in the host. Consequently, the proteins of ES are potential vaccine molecules and potential therapeutic agents for autoimmune diseases. Heligmosomoides polygyrus bakeri, a gastrointestinal parasite of mice, is a model of hookworm infection in humans. ES produced by both sexes of H. polygyrus bakeri L4 stage cultured separately shows different immunomodulatory properties than ES obtained when both sexes are cultured together. Accordingly, the objective of this study was to identify and compare the excretory-secretory molecules from single-sex and mixed cultures. Methods The composition of ES of male and female L4 stage nematodes in the presence (cultured together) or absence (cultured alone) of the opposite sex was examined. Proteins were identified using mass spectrometry. The functions of identified proteins were explored with Blast2GO. Results A total of 258 proteins derived from mixed larval culture in the presence of sex pheromones were identified, 160 proteins from pure female cultures and 172 from pure male cultures. Exposure of nematodes to the sex pheromones results in abundant production of proteins with immunomodulatory properties such as Val proteins, acetylcholinesterases, TGF-β mimic 9 and HpARI. Proteins found only in ES from mixed larval cultures were TGF-β mimics 6 and 7 as well as galectin. Conclusions The presence of the opposite sex strongly influences the composition of ES products, probably by chemical (pheromone) communication between individuals. However, examination of the composition of ES from various conditions gives an opportunity for searching for new potentially therapeutic compounds and anthelminthics as well as components of vaccines. Manipulation of the nematode environment might be important for the studies on the immunomodulatory potential of nematodes. Graphical Abstract

The precopulatory behaviour of the larviform females of Ripidius quadriceps Abeille de Perrin, 1872 is described. The calling posture of virgin females is documented. The cephalic morphology and microstructures are visualised using scanning electron microscopy, in particular the secretory pores in the cuticle of inflatable maxillary palps. An exhaustive overview of relevant publications revealed that the location of secretory pores on the head of females is unique within the order Coleoptera. Compared to other beetles with sedentary calling females, the calling phase of the short-lived and non-feeding female of Ripidius is exceptionally short. For bioassays, various traps using virgin females of Ripidius were tested. It is likely that the sedentary behaviour of the short-lived female combined with a unique morphology and priority for investing in reproduction is compensated for by the actively flying males with remarkably flabellate antennae. The life cycle of this species, including some of the exceptions recorded at the individual level, is discussed. Perspectives for a biological and morphological survey of this rarely collected western Palaearctic species are outlined. In addition, the calling behaviour, secretory sites and location of pheromone glands in females of Coleoptera producing long range pheromones is reviewed.

Background Olfactory cues have been shown to have an important role in guiding gravid mosquito females to selected sites for egg laying. The objective of this study was to determine the influence of emanations from soil from a breeding site and the putative oviposition pheromone nonane on oviposition-site selection of natural populations of Anopheles gambiae sensu lato (s.l.) and Culex quinquefasciatus. Methods This field-based study was conducted in Mvomero District in East-central Tanzania. In a dual-choice experimental set up, clay bowls were dug into the ground and filled with one of the following treatments: (i) distilled water + autoclaved soil (control), (ii) distilled water + soil from a natural mosquito breeding site, (iii) distilled water + nonane and (iv) distilled water + nonane + soil from a natural breeding site. Soil was dried and autoclaved or dried only before use. After five days of incubation, larvae were collected daily for 10 days. The median number of larvae per bowl per day was used as outcome measure. Results Autoclaved soil had a significant attractive effect on oviposition behaviour of Cx. quinquefasciatus (median values ± s.e: 8.0 ± 1.1; P An. gambiae (median value ± s.e: 0.0 ± 0.2; P = 0.18). Nonane and emanations from untreated soil significantly and positively influenced the selection of oviposition sites by both An. gambiae s.l. (median values ± s.e.: 12.0 ± 2.0 and 4.5 ± 1.5, respectively; P Cx. quinquefasciatus (median values ± s.e.: 19.0 ± 1.3 and 17.0 ± 2.0, respectively; P < 0.0001). A mixture of nonane and untreated soil caused a synergistic effect on oviposition behaviour in An. gambiae s.l. (median value ± s.e.: 23.5 ± 2.5; P P P Cx. quinquefasciatus (median value ± s.e.: 41.0 ± 2.1; P P ) or untreated soil alone (median value ± s.e.: 17.0 ± 2.0; P An. gambiae was 0.56 (P Cx. quinquefasciatus 0.59 (P Conclusions The larval pheromone nonane and emanations from breeding-site soil both induced oviposition in wild An. gambiae s.l. and Cx. quinquefasciatus, with a synergistic effect when both stimuli were present simultaneously. This is the first study in which nonane is shown to cause oviposition under natural conditions, suggesting that this compound can potentially be exploited for the management of mosquito vectors.

An arrayed combination of water-soluble deep cavitands and cationic dyes has been shown to optically sense insect pheromones at micromolar concentration in water. Machine learning approaches were used to optimize the most effective array components, which allows differentiation between small structural differences in targets, including between different diastereomers, even though the pheromones have no innate chromophore. When combined with chiral additives, enantiodiscrimination is possible, dependent on the size and shape of the pheromone.

Pheromones are communication chemicals and regulatory signals used by animals and represent unique tools for organisms to mediate behaviors and make "decisions" to maximize their fitness. Phenotypic plasticity refers to the innate capacity of a species to tolerate a greater breadth of environmental conditions across which it adapts to improve its survival, reproduction, and fitness. The pinewood nematode, Bursaphelenchus xylophilus, an invasive nematode species, was accidentally introduced from North America into Japan, China, and Europe; however, few studies have investigated its pheromones and phenotypic plasticity as a natural model. Here, we demonstrated a novel phenomenon, in which nematodes under the condition of pheromone presence triggered increased reproduction in invasive strains (JP1, JP2, CN1, CN2, EU1, and EU2), while it simultaneously decreased reproduction in native strains (US1 and US2). The bidirectional effect on fecundity, mediated by presence/absence of pheromones, is henceforth termed pheromone-regulative reproductive plasticity (PRRP). We further found that synthetic ascaroside asc-C5 (ascr#9), the major pheromone component, plays a leading role in PRRP and identified 2 candidate receptor genes, Bxydaf-38 and Bxysrd-10, involved in perceiving asc-C5. These results suggest that plasticity of reproductive responses to pheromones in pinewood nematode may increase its fitness in novel environments following introduction. This opens up a new perspective for invasion biology and presents a novel strategy of invasion, suggesting that pheromones, in addition to their traditional roles in chemical signaling, can influence the reproductive phenotype among native and invasive isolates. In addition, this novel mechanism could broadly explain, through comparative studies of native and invasive populations of animals, a potential underlying factor behind of the success of other biological invasions.

Toxic puffers accumulate their defense substance (tetrodotoxin; TTX) through the food chain. Although the previous study suggests that 5,6,11-trideoxyTTX, a nontoxic TTX analog detected simultaneously with TTX in toxic puffers or their prey, acts as an olfactory chemoattractant for grass puffers, it is unclear whether toxic puffers are commonly attracted to 5,6,11-trideoxyTTX, and which types of olfactory sensory neurons (OSNs) detect 5,6,11-trideoxyTTX. Here, we demonstrated that green spotted puffer, a phylogenetically distant species from the grass puffer, is attracted to 5,6,11-trideoxyTTX. 5,6,11-TrideoxyTTX administration made green spotted puffers stay longer at the administered site, whereas a food odor (l-Arg) made them actively swim throughout the aquarium. Attractive responses were not observed when TTX or its vehicle was administered, nor when 5,6,11-trideoxyTTX was administered to anosmic fish. Furthermore, double immunohistochemistry with activity marker and crypt OSN marker antibodies labeled oval cells with apical invagination on the olfactory epithelium surface treated with 5,6,11-trideoxyTTX. These results suggest that 5,6,11-trideoxyTTX acts as an olfactory chemoattractant detected by crypt OSNs, and attraction to 5,6,11-trideoxyTTX odor appears to be a trait shared by toxic puffers for social communication or effective toxification.

Reproductive synchrony generally occurs in various group-living animals. However, the underlying mechanisms remain largely unexplored. The migratory locust,Since 2019, a plague of flying insects known as migratory locusts has been causing extensive damage to crops in East Africa. Migratory locusts sometimes live a solitary lifestyle but, if environmental conditions allow, they form large groups containing millions of individuals known as swarms that are responsible for causing locust plagues.Locusts are able to maintain such large swarms because they can aggregate and synchronize. When they live in swarms, individual locusts produce odors that are sensed by other individuals in the group. For example, an aggregation pheromone, called 4-vinylanisole, is known to help keep large groups of locusts together. However, it is less clear how odors synchronize the reproductive cycles of the females in a swarm so that they are ready to mate with males and lay their eggs at the same time. To address this question, Chen et al. examined when female locusts reached sexual maturity after they were exposed to odors produced by other locusts living alone or in groups. The experiments found that only 4-vinylanisole, which was abundantly released by adult male locusts living in groups, stimulated female locusts to reach sexual maturity at the same time. This odor increased the levels of a hormone known as juvenile hormone in less-developed females to help them reach sexual maturity sooner. These findings demonstrate that when migratory locusts are living in swarms, male locusts promote the female locusts to reach sexual maturity at the same time by promoting less-developed females to ‘catch up’ with other females in the group. A next step will be to investigate the neural and molecular mechanisms underlying the ‘catch up’ effect induced by 4-vinylanisole.

The coconut rhinoceros beetle, Oryctes rhinoceros (Linnaeus 1758) (Coleoptera: Scarabaeidae: Dynastinae) (CRB), is endemic to tropical Asia where it damages both coconut and oil palm. A new invasion by CRB occurred on Guam in 2007 and eradication attempts failed using commonly applied Oryctes rhinoceros nudivirus (OrNV) isolates. This and subsequent invasive outbreaks were found to have been caused by a previously unrecognized haplotype, CRB-G, which appeared to be tolerant to OrNV. The male-produced aggregation pheromone of the endemic, susceptible strain of O. rhinoceros (CRB-S) was previously identified as ethyl 4-methyloctanoate. Following reports from growers that commercial lures containing this compound were not attractive to CRB-G, the aim of this work was to identify the pheromone of CRB-G. Initial collections of volatiles from virgin male and female CRB-G adults from the Solomon Islands failed to show any male- or female-specific compounds as candidate pheromone components. Only after five months were significant quantities of ethyl 4-methyloctanoate and 4-methyloctanoic acid produced by males but not by females. No other male-specific compounds could be detected, in particular methyl 4-methyloctanoate, 4-methyl-1-octanol, or 4-methyl-1-octyl acetate, compounds identified in volatiles from some other species of Oryctes. Ethyl 4-methyloctanoate elicited a strong electroantennogram response from both male and female CRB-G, but these other compounds, including 4-methyloctanoic acid, did not. The enantiomers of ethyl 4-methyloctanoate and 4-methyloctanoic acid were conveniently prepared by enzymatic resolution of the commercially-available acid, and the enantiomers of the acid, but not the ester, could be separated by gas chromatography on an enantioselective cyclodextrin phase. Using this approach, both ethyl 4-methyloctanoate and 4-methyloctanoic acid produced by male CRB-G were shown to be exclusively the (R)-enantiomers whereas previous reports had suggested male O. rhinoceros produced the (S)-enantiomers. However, re-examination of the ester and acid produced by male CRB-S from Papua New Guinea showed that these were also the (R)-enantiomers. In field trapping experiments carried out in the Solomon Islands, both racemic and ethyl (R)-4-methyloctanoate were highly attractive to both male and female CRB-G beetles. The (S)-enantiomer and the corresponding acids were only weakly attractive. The addition of racemic 4-methyloctanoic acid to ethyl 4-methyloctanoate did significantly increase attractiveness, but the addition of (R)- or (S)-4-methyloctanoic acid to the corresponding ethyl esters did not. Possible reasons for the difference in assignment of configuration of the components of the CRB pheromone are discussed along with the practical implications of these results.

Most mammals rely on chemosensory cues for individual recognition, which is essential to many aspects of social behavior, such as maternal bonding, mate recognition, and inbreeding avoidance. Both volatile molecules and nonvolatile peptides secreted by individual conspecifics are detected by olfactory sensory neurons in the olfactory epithelium and the vomeronasal organ. The pertinent cues used for individual recognition remain largely unidentified. Here we show that nonformylated, but not N-formylated, mitochondrially encoded peptides—that is, the nine N-terminal amino acids of NADH dehydrogenases 1 and 2—can be used to convey strain-specific information among individual mice. We demonstrate that these nonformylated peptides are sufficient to induce a strain-selective pregnancy block. We also observed that the pregnancy block by an unfamiliar peptide derived from a male of a different strain was prevented by a memory formed at the time of mating with that male. Our findings also demonstrate that pregnancy-blocking chemosignals in the urine are maternally inherited, as evidenced by the production of reciprocal sons from two inbred strains and our test of their urine’s ability to block pregnancy. We propose that this link between polymorphic mitochondrial peptides and individual recognition provides the molecular means to communicate an individual’s maternal lineage and strain.

Trypodendron retusum (LeConte) (Coleoptera: Curculionidae: Scolytinae) females excised from newly attacked trembling aspen, Populus tremuloides Michaux (Salicaceae), were shown for the first time to produce the aggregation pheromone (+)-lineatin. Coupled gas chromatographic-electroantennographic detection analysis (GC-EAD) disclosed that the antennae of T. retusum, as well as the antennae of three sympatric species, native T. lineatum (Olivier) and T. rufitarsus (Kirby) and exotic T. domesticum (L.), respond to synthetic (+)-lineatin, but not the (−) enantiomer. In contrast, the antennae of T. betulae Swaine responded to SR- and RR-linalool oxide pyranoid and did not detect lineatin. GC-EAD analysis of volatiles from host and nonhost tree species revealed that conifer-produced α-pinene and angiosperm-produced conophthorin and salicylaldehyde were perceived by the antennae of all three native lineatin-perceiving species, suggesting behavioral activity. Field trapping experiments showed that salicylaldehyde synergized the response of coastal, but not interior, T. retusum to lineatin and inhibited the response of T. lineatum and T. rufitarsus. In the absence of salicylaldehyde, α-pinene appeared to inhibit the response of interior T. retusum to lineatin, while for T. lineatum and T. rufitarsus it had an apparent positive additive or synergistic effect. No behavioral response occurred to conophthorin. The results provide evidence for semiochemical-based reproductive isolation between T. retusum and T. betulae, and between these two angiosperm-infesting species and the two conifer-infesting species. They do not explain how isolation could be maintained between T. lineatum and T. rufitarsus.

Flying insects are known to orient themselves over large distances using minute amounts of odors. Some bear pectinate antennae of remarkable architecture thought to improve olfactory per- formance. The semiporous, multiscale nature of these antennae influences how odor molecules reach their surface. We focus here on the repeating structural building blocks of these antennae in Saturniid moths. This microstructure consists of one ramus or branch and its many hair-like sensilla, responsible for chemical detection. We experimentally determined leakiness, defined as the proportion of air going through the microstructure rather than flowing around it, by particle image velocimetry visualization of the flow around three-dimensional printed scaled-up mock-ups. The combination of these results with a model of mass transfer showed that most pheromone molecules are deflected around the microstructure at low flow velocities, keeping them out of reach. Capture is thus determined by leakiness. By contrast, at high velocities, molecular diffusion is too slow to be effective, and the molecules pass through the structure without being captured. The sensory structure displays maximal odor capture efficiency at intermediate flow speeds, as encountered by the animal during flight. These findings also provide a rationale for the previously described “olfactory lens,” an increase in pheromone reception at the proximal end of the sensors. We posit that it is based on passive mass transfer rather than on physicochemical surface processes.

The walnut twig beetle, Pityophthorus juglandis Blackman, and its associated fungal pathogen that causes thousand cankers disease, currently threaten the viability of walnut trees across much of North America. During a 2011 assessment of seasonal flight patterns of P. juglandis with yellow sticky traps baited with the male-produced aggregation pheromone component, 3-methyl-2-buten-1-ol, dramatically reduced catches were recorded when Tree Tanglefoot adhesive was used to coat the traps. In summer 2011, two trap adhesives were tested for potential repellency against P. juglandis in a field trapping bioassay. SuperQ extracts of volatiles from the most repellent adhesive were analyzed by gas chromatography–mass spectrometry, and limonene and α-pinene were identified as predominant components. In field-based, trapping experiments both enantiomers of limonene at a release rate of ~700 mg/d conferred 91–99% reduction in trap catches of P. juglandis to pheromone-baited traps. (+)- and (‒)-α-Pinene reduced trap catch by 40 and 53%, respectively, at the highest release rate tested. While a combination of R-(+)-limonene and (+)-α-pinene resulted in a 97% reduction in the number of P. juglandis caught, the combination did not consistently result in greater flight trap catch reduction than individual limonene enantiomers. The repellent effect of limonene may be valuable in the development of a semiochemical-based tool for management of P. juglandis and thousand cankers disease.

Mormidea v-luteum (Lichtenstein, 1796) feeds on commercial crops, such as rice and ryegrass, causing damage that slows growth and reduces productivity. With the aim of developing an eco-friendly control technique, we investigated the compounds involved in chemical communication in this species. The volatiles produced by a group of seven males or females allocated to different aerated glass chambers were collected for 24 h and analyzed by gas chromatograph/mass spectrometry and gas chromatography/Fourier transform infrared spectroscopy. The analyses showed six male-specific compounds, identified as two isomers of zingiberenol (compounds 1 and 2), three isomers of murgantiol (3, 5 and 6) and sesquipiperitol (4). Compounds 1 and 5 were the major components and were produced in a ratio of 6:4. The absolute stereochemistry of the two isomers of zingiberenol was established as (1S,4R,1'S)-1 and (1R,4R,1'S)-2 by chiral gas chromatography. Stereochemistry was not determined for all the other molecules. To confirm the attractiveness of these chemicals, bioassays were performed in a Y-tube olfactometer, first using crude extracts and, subsequently, synthetic compounds. Male volatiles were attractive to both sexes, demonstrating an aggregation pheromone. In bioassays with synthetic compounds, (1'S)-zingiberenol was highly attractive to both males and females. However, when (1'S)-murgantiol was tested, only females were attracted. Interestingly, when a mixture of zingiberenol and murgantiol isomers was tested, it was attractive to both sexes, with females more attracted to the mixture than to zingiberenol alone; males did not distinguish between treatments. Thus, the bioassay data suggest that the molecules have different functions in chemical communication of this species: zingiberenol acts primarily as an aggregation pheromone, while murgantiol plays a role as a sex pheromone.

The use of insect sex pheromones is an alternative technology for pest control in agriculture and forestry, which, in contrast to insecticides, does not have adverse effects on human health or environment and is efficient also against insecticide-resistant insect populations.1,2 Due to the high cost of chemically synthesized pheromones, mating disruption applications are currently primarily targeting higher value crops, such as fruits.3 Here we demonstrate a biotechnological method for the production of pheromones of economically important moth pests using engineered yeast cell factories. Biosynthetic pathways towards several pheromones or their precursors were reconstructed in the oleaginous yeast Yarrowia lipolytica, which was further metabolically engineered for improved pheromone biosynthesis by decreasing fatty alcohol degradation and downregulating storage lipid accumulation. The sex pheromone of the cotton bollworm Helicoverpa armigera was produced by oxidation of fermented fatty alcohols into corresponding aldehydes. The resulting pheromone was just as efficient and specific for trapping of H. armigera male moths in cotton fields in Greece as a synthetic pheromone mixture. We further demonstrated the production of the main pheromone component of the fall armyworm Spodoptera frugiperda. Our work describes a biotech platform for the production of commercially relevant titres of moth pheromones for pest control by yeast fermentation.Significance statementAgriculture largely relies on insecticides and genetically modified crops for pest control, however alternative solutions are required due to emerging resistance, toxicity and regulatory issues, and consumer preferences. Mating disruption with sex pheromones that act by preventing insect reproduction is considered the most promising and scalable alternative to insecticides. This method is highly efficient and safe for human health and environment. The likelihood of insect resistance development is very low and can be handled by adjusting the pheromone composition. The high cost of chemically synthesized pheromones is the major barrier for the wider adoption of pheromones. A novel method based on yeast fermentation enables the production of insect sex pheromones as a lower cost from renewable feedstocks.

The Chinese oak silkworm, Antheraea pernyi, has not only been semi-domesticated as an important economical insect but also used for genetic research. The female moths of A. pernyi employ a pheromone blend containing (E,Z)-6,11-hexadecadienal (E6,Z11-16:Ald), (E,Z)-6,11-hexadecadienyl acetate (E6,Z11-16:OAc), and (E,Z)-4,9-tetradecadienyl acetate (E4,Z9-14:OAc). While its biosynthesis pathway is largely unknown. By deep sequencing and de novo assembly of sex pheromone gland (PG) transcriptome, we identified 141 candidate genes that are putatively related to pheromone biosynthesis, degradation, and chemoreception in A. pernyi. Gene expression patterns and phylogenetic analysis revealed that two desaturases (AperDES1 and 2), two fatty acid reductase (AperFAR1 and 2), and three acetyltransferase genes (AperACT1, 2 and 3) showed PG-biased or specific expression and were phylogenetically related to genes known to be involved in pheromone synthesis in other species. Furthermore, two carboxylesterases (AperCOE6 and 11) and two chemosensory protein (AperCSP1 and 6) were also expressed specifically or predominantly in the PGs, which might be related to sex pheromone degradation and transportation, respectively. Based on these results, the sex pheromone biosynthesis and metabolic pathway was proposed in A. pernyi. This study provides some crucial candidates for further functional elucidation, and may be used for interfering sexual communication in other Saturniidae pests.

Whether stored-grain insects can communicate with each other inside stored-grain bulks is an important question for the development of pest management programs. Movements of the individual adults of Cryptolestes ferrugineus towards caged adult(s), in the presence or absence of wheat, were studied inside an apparatus (10 cm length), using an infrared camera. The numbers of the caged adults were 1, 20, or 50 of females or males, and 100 or 200 mixed-sex adults. Without grain, both males and females moved towards the caged single male, but not the caged single female. With grain, neither males nor females moved towards the caged single male or female. When 50 males were added to the cage, females did move significantly towards the caged males. There were trends for introduced males and females to move towards caged males at higher densities.

The insect olfactory system operates as a well-choreographed ensemble of molecules which functions to selectively translate volatile chemical messages present in the environment into neuronal impulses that guide insect behaviour. Of these molecules, binding proteins are believed to transport hydrophobic odorant molecules across the aqueous lymph present in antennal sensilla to receptors present in olfactory sensory neurons. Though the exact mechanism through which these proteins operate is still under investigation, these carriers clearly play a critical role in determining what an insect can smell. Binding proteins that transport important sex pheromones are colloquially named pheromone binding proteins (PBPs). Here, we have produced a functional recombinant PBP from the horticultural pest, Epiphyas postvittana (EposPBP3), and experimentally solved its apo-structure through X-ray crystallography to a resolution of 2.60 Å. Structural comparisons with related lepidopteran PBPs further allowed us to propose models for the binding of pheromone components to EposPBP3. The data presented here represent the first structure of an olfactory-related protein from the tortricid family of moths, whose members cause billions of dollars in losses to agricultural producers each year. Knowledge of the structure of these important proteins will allow for subsequent studies in which novel, olfactory molecule-specific insecticides can be developed.