Interaction between females and males grapevine moth Lobesia botrana modifies further mating preference.

During reproduction, females may boost their fitness by being selective based on direct material benefits provided by the males, such as nuptial gifts. In Lepidoptera, male provides a spermatophore containing nutrients. However, virgin males produce a bigger spermatophore, containing spermatozoa and nutrients, allowing higher female fertility. Lepidoptera females that could detect the sexual status of males may thus prefer a male without previous mating experience (i.e. a virgin male). This mate selection could be achieved by the use of chemical indices, such as sexual pheromones and cuticular compounds, known to be possibly exchanged during reproduction, and which can be indicators of a previous mating experience and known to be possibly sources of information exchanged. In this study, we experimentally presented Lobesia botrana virgin males with females in order for them to be exposed to females' natural sexual pheromones or cuticular compounds. 12 or 48 h after the exposure of males to either females' sexual pheromones or cuticular compounds, these males were confronted to naïve females, which have a choice between them or a virgin non-exposed males. We highlighted that, despite producing a spermatophore of similar volume, all exposed virgin males were less likely to mate with females 12 h after exposure, while after 48 h of exposure this is only the case for virgin males exposed to sexual pheromones. L. botrana females may thus discriminate male sexual experience based on chemical cues (either from cues transferred directly from females to males, or from changes in the cuticular or pheromone males' profile) indicating past mating experiences. Mating duration was longer for males exposed to sexual pheromones after 12 h only, and for males exposed to cuticular compounds after 48 h only. Pheromones signal might be more persistent over time and seems to more easily gather information for males. The physiological reasoning behind this result still needs to be investigated.

Evidence for 3-hydroxyhexan-2-one as a shared pheromone component for 12 South American species of cerambycid beetles.

3-Hydroxyhexan-2-one (3-C6-ketol) has emerged as the most conserved pheromone structure within the beetle family Cerambycidae. In this study, we report the sex-specific production of this compound by males of 12 species of South American cerambycid beetles. Males of Chrysoprasis chalybea Redtenbacher and Mallosoma zonatum (Sahlberg) (Tribe Dichophyiini), and Ambonus lippus (Germar), Eurysthea hirta (Kirby), Pantonyssus nigriceps Bates, Stizocera plicicollis (Germar), and Stizocera tristis (Guérin-Méneville) (Elaphidiini) produced 3R-C6-ketol as a single component, whereas males of Neoclytus pusillus (Laporte & Gory) (Clytini), Aglaoschema concolor (Gounelle), Orthostoma abdominale (Gyllenhal) (Compsocerini), Dorcacerus barbatus (Olivier), and Retrachydes thoracicus thoracicus (Olivier) (Trachyderini) produced 3R-C6-ketol, along with lesser amounts of other compounds. In field trials testing 8 known cerambycid pheromone compounds, C. chalybea, E. hirta, and R. t. thoracicus were attracted in significant numbers to traps baited with 3-C6-ketol. A second field experiment provided support for the strategy of using the attraction of cerambycid species to test lures as a method of providing leads to their likely pheromone components. Because both sexes are attracted to these aggregation-sex pheromones, live beetles can be obtained from baited traps to verify they produce the compound(s) to which they were attracted, that is, that the compounds are indeed pheromone components.

Identification, synthesis, and field evaluation of components of the female-produced sex pheromone of Helopeltis cinchonae (Hemiptera: Miridae), an emerging pest of tea.

BACKGROUND: Helopeltis cinchonae (Hemiptera: Miridae) is a major pest of tea plantations in Asia. Conventional control of pests with pesticides is unsustainable. Therefore, safe and eco-friendly alternatives, such as pheromones, are required to manage the pest. RESULTS: In gas chromatography-electroantennographic detection (GC-EAD) analysis of whole-body extracts of virgin female H. cinchonae, two compounds elicited electroantennogram (EAG) responses from male antennae. These were identified as hexyl (R)-3-acetoxybutyrate and (R)-1-acetoxy-5-butyroxyhexane using gas chromatography-mass spectrometry (GC-MS) analysis compared to synthetic compounds. This is the first study to report 1-acetoxy-5-butyroxyhexane as an insect pheromone component. The synthetic compounds elicited dose-dependent EAG responses from the antennae of male H. cinchonae. In two field trapping experiments, the individual compounds were highly attractive to male H. cinchonae when dispensed from polyethylene vials. However, higher catches were obtained with blends of the two compounds in a 1:10 ratio. The blend of racemic compounds was as attractive as the blend of (R)-enantiomers. CONCLUSIONS: We reported that 1-acetoxy-5-butyroxyhexane and hexyl 3-acetoxybutyrate are components of the female-produced sex pheromone of H. cinchonae, but further work is required on the blend and loading of pheromone and on trap design to provide an optimized system for monitoring and control of this pest. The results may also facilitate the identification of the pheromones of other Helopeltis species, which are major pests in many crops. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of deploying ethanol lures in tandem with generic pheromone lures for attraction of cerambycid beetles in field bioassays.

Male cerambycid beetles of the large subfamilies Cerambycinae and Lamiinae produce aggregation-sex pheromones that attract both sexes. The pheromones of many species are conserved among both closely related species (e.g., congeners) and more distantly related species (e.g., different subfamilies), including those endemic to different continents. This parsimony in pheromone structures suggests that multiple species may be attracted to traps baited with blends of pheromones, and such blends are finding use in delineating geographic ranges of native species and in surveillance programs for incursions of exotic species. Here, we present the results of a field experiment conducted at multiple sites in Iowa that tested the effects of deploying ethanol lures in tandem with a 6-component blend of common pheromone components for cerambycine and lamiine species and a 5-component blend that specifically targeted lamiines. Eight cerambycine species showed significant treatment effects, most of which were attracted to the 6-component blend, and ethanol increased attraction for half of these species. Two cerambycine species were attracted only by ethanol. Seven lamiine species were attracted by the lamiine-specific blend, alone or when combined with ethanol, and 3 of these species also were attracted to the 6-component blend. Taken together, these findings provide further evidence that carefully crafted blends of pheromones can be used to monitor the presence or abundance of multiple cerambycid species. Ethanol either increased the number of beetles attracted by pheromones or had no effect, so there is no apparent downside to deploying ethanol lures in combination with pheromones.

(Z, Z, Z)-3,6,9-Nonadecadiene, a potential inhibitor of sex pheromone of Grey Tea Geometrid (Lepidoptera: Geometridae): electroantennogram test, wind tunnel, and in silico study.

Sex pheromone analogs have high structural similarity to sex pheromone components. They also play a role in studying many agricultural pests. In our study, (Z, Z, Z)-3,6,9-nonadecadiene (Z3Z6Z9-19:Hy) was successfully synthesized, which is an analogue to 1 of 2 sex pheromone components of Ectropis grisescens Warren (Z, Z, Z)-3,6,9-octadecatriene (Z3Z6Z9-18:Hy), and it showed potential inhibition in experiments. In the electroantennogram test, Z3Z6Z9-19:Hy showed a dose-dependent response, and only measured half the response of Z3Z9-6,7-epo-18:Hy. However, the compound significantly reduced positive response of E. grisescens males by up to 70% in the Y-tube olfactometer. Furthermore, in the wind tunnel, it significantly inhibited all types of behavioral responses. The percentage of moths contacting the pheromone odor source was reduced even at the lowest dose tested. In silico study afterward, molecular docking results showed affinity between Z3Z6Z9-19:Hy and sensory neuron membrane protein 1. Our study revealed the potential of Z3Z6Z9-19:Hy as a sex pheromone inhibitor, which would provide new tools for monitoring and mating disruption of E. grisescens.

(R)-(+)-γ-Decalactone is Conserved in North America as a Pheromone Component of Osmoderma eremicola (Coleoptera: Scarabaeidae) and a Kairomone of Elater abruptus (Coleoptera: Elateridae).

The scarab genus Osmoderma (Coleoptera: Scarabaeidae) includes several large species called hermit beetles that develop within dead and decaying hardwood trees. Males of at least three Palearctic species produce the aggregation-sex pheromone (R)-(+)-γ-decalactone, including the endangered O. eremita (Scopoli). However, hermit beetles have received less attention in the western hemisphere, resulting in a large gap in our knowledge of the chemical ecology of Nearctic species. Here, we identify (R)-( +)-γ-decalactone as the primary component of the aggregation-sex pheromone of the North American species Osmoderma eremicola (Knoch). Field trials at sites in Wisconsin and Illinois revealed that both sexes were attracted to lures containing (R)-(+)-γ-decalactone or the racemate, but only males of O. eremicola produced the pheromone in laboratory bioassays, alongside an occasional trace of the chain-length analog γ-dodecalactone. Females of the congener O. scabra (Palisot de Beauvois) were also significantly attracted by γ-decalactone, suggesting further conservation of the pheromone, as were females of the click beetle Elater abruptus Say (Coleoptera: Elateridae), suggesting that this compound may have widespread kairomonal activity. Further research is needed to explore the behavioral roles of both lactones in mediating behavioral and ecological interactions among these beetle species.

Replenishment of Drosophila Male Pheromone After Mating.

Insect exocrine gland products can be involved in sexual communication, defense, territory labelling, aggregation and alarm. In the vinegar fly Drosophila melanogaster the ejaculatory bulb synthesizes and releases 11-cis-Vaccenyl acetate (cVa). This pheromone, transferred to the female during copulation, affects aggregation, courtship and male-male aggressive behaviors. To determine the ability of male flies to replenish their cVa levels, males of a control laboratory strain and from the desat1 pheromone-defective mutant strain were allowed to mate successively with several females. We measured mating frequency, duration and latency, the amount of cVa transferred to mated females and the residual cVa in tested males. Mating duration remained constant with multiple matings, but we found that the amount of cVa transferred to females declined with multiple matings, indicating that, over short, biologically-relevant periods, replenishment of the pheromone does not keep up with mating frequency, resulting in the transfer of varying quantities of cVa. Adult responses to cVa are affected by early developmental exposure to this pheromone; our revelation of quantitative variation in the amount of cVa transferred to females in the event of multiple matings by a male suggests variable responses to cVa shown by adults produced by such matings. This implies that the natural role of this compound may be richer than suggested by laboratory experiments that study only one mating event and its immediate behavioral or neurobiological consequences.

Courtship and mating behavior of Endoclita signifer (Hepialidae: Lepidoptera) and the male sex pheromones in hairbrushes.

Endoclita signifer Walker is the most destructive wood-boring pest of Eucalyptus in China, causing significant economic and ecological damage. As an insect of the primitive Lepidoptera family Hepialidae, E. signifer fly and mat for only 10-20 min at dusk. The courtship and mating behavior of E. signifer adults and whether male moths release sex pheromones are still unknown, especially since transitory flight survival strategies in primitive moths differ from advanced moths like noctuids. In this study, we first observed the courtship and mating behavior of E. signifer by considering the effects of space and then analyzed extracts of male hairbrushes using gas chromatography-electroantennogram detection. Our results indicated that during the courtship period, flying males form courtship fields, lekking, and chase flying females before mating with them; E. signifer were more successful in mating in larger spaces (Length × Width × Height = 9.6 × 7 × 4 m); 5 compounds in the hairbrushes of the male moths which elicited antennal responses of 2 sexes, despite at high concentrations. Combined with it, indicating that communication between male and female may rely on male sex pheromones. These findings can serve as a basis for studying the mechanisms of sex communication in E. signifer and developing sex pheromone-based trapping techniques.

The greening-causing agent alters the behavioral and electrophysiological responses of the Asian citrus psyllid to a putative sex pheromone.

The Asian Citrus Psyllid (ACP), Diaphorina citri, is a vector of the pathological bacterium Candidatus Liberibacter asiaticus (CLas), which causes the most devastating disease to the citrus industry worldwide, known as greening or huanglongbing (HLB). Earlier field tests with an acetic acid-based lure in greening-free, 'Valencia' citrus orange groves in California showed promising results. The same type of lures tested in São Paulo, Brazil, showed unsettling results. During the unsuccessful trials, we noticed a relatively large proportion of females in the field, ultimately leading us to test field-collected males and females for Wolbachia and CLas. The results showed high rates of Wolbachia and CLas infection in field populations. We then compared the olfactory responses of laboratory-raised, CLas-free, and CLas-infected males to acetic acid. As previously reported, CLas-uninfected males responded to acetic acid at 1 µg. Surprisingly, CLas-infected males required 50 × higher doses of the putative sex pheromone, thus explaining the failure to capture CLas-infected males in the field. CLas infection was also manifested in electrophysiological responses. Electroantennogram responses from CLas-infected ACP males were significantly higher than those obtained with uninfected males. To the best of our knowledge, this is the first report of a pathogen infection affecting a vector's response to a sex attractant.

Methionol as an aggregation-sex pheromone of the desert-dwelling beetle Eustromula valida (Coleoptera: Cerambycidae).

As part of a long-term project on unraveling the use of pheromones in the large beetle family Cerambycidae, field trials were conducted with generic blends of known cerambycid pheromones at a desert site in southern California. In the first year of testing (2022), the species Eustromula valida (LeConte) (subfamily Cerambycinae, tribe Elaphidiini) and Aethecerinus latecinctus (Horn) (Cerambycinae, Trachyderini) were weakly attracted to one of the lure blends. In follow-up trials in 2023, only E. valida were caught, and collection of volatiles from both sexes of E. valida determined that males sex-specifically produced 3-methylthiopropan-1-ol (methionol), a compound that was not in the tested lure blends. Beetles of both sexes were strongly and specifically attracted to this compound in field bioassays, verifying that it is an aggregation-sex pheromone. No sympatric species were attracted to methionol while it was deployed in the field. Several recent studies have identified methionol as a pheromone component for other cerambycid species in both North and South America, suggesting it may represent another common pheromone component within the Cerambycidae.

More about the role of 2,6-dichlorophenol in tick courtship: identification and olfactometer bioassay in Amblyomma cajennense and Rhipicephalus sanguineus

This study aimed to identify 2,6-dichlorophenol (2,6-DCP) in Amblyomma cajennense and to evaluate its role in A. cajennense and Rhipicephalus sanguineus courtship. Hexanic extract from attractive females was purified by solid phase extraction and the phenol was identified by the single ion monitoring method using GC/MS. In an olfactometer, the responses of A. cajennense and R. sanguineus males to females, control rubber septa or rubber septa impregnated with 2,6-DCP at 50, 500, and 5000 ng, respectively, were studied. 2,6-DCP was identified in A. cajennense extract and the males oriented themselves toward the concentration of 500 ng. These septa and the females were recognized as copula partners. The septa treated with 2,6-DCP did not attract and were not even recognized by the R. sanguineus males, whereas the females were recognized. Due to the presence of 2,6-DCP in A. cajennense and the results of biological bioassays, it was concluded that this compound acts as an attractant and mounting sex pheromone in this tick, but it does not play any role in R. sanguineus courtship.