Anti-aphrodisiac pheromone:Pheromone Resources

Anti-aphrodisiac pheromone (diminish sexual desire):

This pheromone is reported in Heliconius melpomene Linnaeus (Lepidoptera:Nymphalidae) (Schulz, 2008). The pheromones of Heliconius melpomene, of males contained the volatile compound (E)-β-ocimene along woth volatile matrix of esters of common C₁₆- and C₁₈-fatty acids with the alcohols ethanol, 2-propanol, 1-butanol, isobutanol, 1-hexanol, and (Z)-3-hexenol. The  investigation showed that β-ocimene is an antiaphrodisiac pheromone of H. melpomene (Schulz S Estrada et al., 2008).

It is reported that male of Lygus hesperus delivers a large spermatophore and fatty molecule myristyl acetate,which  absent in virgin females. When they found myristyl acetate was as effective reducing the attractiveness of virgin females. Hence, already mated males are less attractive to males compered to virgin fmales  (Colin S. Brent and  John A. Byers, 2011).

In the male ejaculate,P. brassicae females receive the anti-aphrodisiac benzyl cyanide (BC) that reduces the females' attractiveness for subsequent mating. It was  detected this pheromone in the accessory gland secretion released by mated female butterflies. When applied onto leaves, BC alone induced phytochemical changes that arrested females of the egg parasitoid. Microarray analyses revealed a similarity in induced plant responses that may explain the arrest of T. brassicae to egg-laden and BC-treated plants. Thus, a male-derived compound endangers the offspring of the butterfly by inducing plant defense (Fatouros et al.,2008).

Behavioural mating assays showed that males mount nymphs significantly shorter time compared to females, although initial mounting preference was the same. In support of our hypothesis, nymphs experienced the same percentage of mating with sperm transfer as females if they were unable to emit (E)-2-hexenal, (E)-2-octenal 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal, from their dorsal abdominal glands. We report that the aldehydes and 4-oxo-(E)-2-hexenal are detected by olfactory receptor neurons housed in smooth and grooved peg sensilla, respectively, on the adult antennae, at biologically relevant concentrations. Behavioural experiments showed that application of 4-oxo-(E)-2-hexenal or the two aldehydes at a nymph-emitted ratio, to a male/female pair during mounting initiation, decreased mating frequency to a rate comparable to that of a male/nymph pair (Harraca et al.,2010).

Courtship conditioning is an associative learning paradigm in Drosophila melanogaster, wherein male courtship behavior is modified by experience with unreceptive, previously mated females. While the training experience with mated females involves multiple sensory and behavioral interactions, we hypothesized that female cuticular hydrocarbons function as a specific chemosensory conditioned stimulus in this learning paradigm. The effects of training with mated females were determined in courtship tests with either wild-type virgin females as courtship targets, or with target flies of different genotypes that express distinct cuticular hydrocarbon (CH) profiles. Results of tests with female targets that lacked the normal CH profile, and with male targets that expressed typically female CH profiles, indicated that components of this CH profile are both necessary and sufficient cues to elicit the effects of conditioning. Results with additional targets indicated that the female-specific 7,11-dienes, which induce naive males to court, are not essential components of the conditioned stimulus. Rather, the learned response was significantly correlated with the levels of 9-pentacosene (9-P), a compound found in both males and females of many Drosophila strains and species. Adding 9-P to target flies showed that it stimulates courting males to attempt to copulate, and confirmed its role as a component of the conditioned stimulus by demonstrating dose-dependent increases in the expression of the learned response. Thus, 9-P can contribute significantly to the conditioned suppression of male courtship toward targets that express this pheromone (Siwicki, et al.,2005).

Closely related egg parasitoids,Trichogramma brassicae and Trichogramma evanescens, exploit the anti-aphrodisiac pheromone benzyl cyanide of one of their hosts, the gregarious large cabbage white butterfly Pieris brassicae that deposits a clutch of more than 20 eggs per oviposition bout. The pheromone is transferred by male butterflies to females during mating to enforce female monogamy. On detecting the anti-aphrodisiac, the tiny parasitic wasps ride on a mated female butterfly to a host plant and then parasitize her freshly laid eggs. The present study demonstrates that both wasp species similarly exploit the anti-aphrodisiac mixture of methyl salicylate and indole of another host, the more common solitary small cabbage white butterfly Pieris rapae that deposits only one egg at a time. Interestingly, this behavior is innate in T. brassicae, whereas T. evanescens learns it after one successful ride on a mated female butterfly. Moreover, we show that the wasps only respond to the anti-aphrodisiacs of the 2 cabbage white butterflies when the ubiquitous compounds are part of a complete mated female odor blend  (Huigens et al.,2010).

In Drosophila melanogaster, the male ejaculatory bulb is the site of synthesis of a male-specific pheromone, cis-vaccenyl acetate, which functions as both an attractant and an anti-aphrodisiac. This long monounsaturated acetate is structurally similar to a number of shorter gland-synthesized moth pheromones. The cell monolayer that forms the Drosophila male ejaculatory bulb wall is responsible for the production and secretion of cis-vaccenyl acetate into the seminal fluid. When dissected bulbs were incubated with sodium [14-C]-acetate (or deuterated acetate), a labeled acetate ester was synthesized. The labeled acetate ester co-migrated with cis-vaccenyl acetate in thin layer chromatography. Incubation of the abdomens of males from which the ejaculatory bulbs had been removed, or the abdomens of females, with radiolabeled acetate did not yield any acetate ester, but did yield other lipid products, including hydrocarbons. When the isolated labeled acetate ester was hydrolyzed, no radioactive vaccenol was formed. This strongly suggests that the acetyl group is incorporated via a transacetylation reaction, but that the vaccenyl moiety is not synthetized in the blub. The transacetylation enzyme activity was localized in the microsomal subfraction of the bulb homogenate, and its affinity for vaccenol was not very different from that reported for monounsaturated alcohol substrates in moths (Guiraudie et al.,2007).

Gas-liquid chromatography was used to investigate the role of cis-vaccenyl acetate, cis-vaccenol and esterase 6 in the inhibition of male courtship in D. melanogaster. Results indicate that (1) cis-vaccenyl acetate is not converted tocis-vaccenol, (2) esterase 6 has no effect on the rate of cis-vaccenyl acetate loss from the reproductive tracts of mated females, (3) in vivo concentrations of cis-vaccenyl acetate transferred to females during copulation fall below effective courtship-inhibitory levels within 4 h, (4) cis-vaccenyl acetate is not translocated from the female reproductive tract to the abdominal cuticle, and that (5) mutant male flies that do not reduce the post-mating sexual attractiveness of females contain and transfer normal amounts of cis-vaccenyl acetate (Vander Meer et al.,1996).

A recent study in BMC Biology has determined that the immature stage of the bed bug (the nymph) signals its reproductive status to adult males using pheromones and thus avoids the trauma associated with copulation in this species. The success of this nymphal strategy of deterrence is instructive. Against the background of increasing problems with bed bugs, this research raises the question whether pheromones might be used to control them (Haynes et al.,2010).

After Drosophila males are rejected by mated females, their subsequent courtship is inhibited even when encountering virgin females. Molecular mechanisms underlying courtship conditioning in the CNS are unclear. In this study, we find that tyramine β hydroxylase (TβH) mutant males unable to synthesize octopamine (OA) showed impaired courtship conditioning, which could be rescued by transgenic TβH expression in the CNS. Inactivation of octopaminergic neurons mimicked the TβH mutant phenotype. Transient activation of octopaminergic neurons in males not only decreased their courtship of virgin females, but also produced courtship conditioning. Single cell analysis revealed projection of octopaminergic neurons to the mushroom bodies. Deletion of the OAMB gene encoding an OA receptor expressed in the mushroom bodies disrupted courtship conditioning. Inactivation of neurons expressing OAMB also eliminated courtship conditioning. OAMB neurons responded robustly to male-specific pheromone cis-vaccenyl acetate in a dose-dependent manner. Our results indicate that OA plays an important role in courtship conditioning through its OAMB receptor expressed in a specific neuronal subset of the mushroom bodies (Zhou et al.,2012).

In polyandrous butterflies males transfer a large, nutritious ejaculate at mating. Larger ejaculates delay female remating and confer an advantage in sperm competition. However, large ejaculates are costly, potentially selecting for male adjustment of ejaculate size to the risk of sperm competition. Here, we test if male ejaculate size in the butterfly Pieris napivaries with male density, and whether males assess sperm competition risk using the male sex pheromone citral as a cue. The results conformed to sperm competition theory and showed that male P. napi tailored their reproductive investment in response to the risk of sperm competition; ejaculates transferred by males in the high male density treatments were on average 23% larger than ejaculates transferred at low male densities. The results also show for the first time that the sex pheromone citral was used by males to assess male density; ejaculates transferred by males in presence of added male sex pheromone were 19% larger than ejaculates transferred in the control. In conclusion, the study shows how the sex pheromone not only facilitates female acceptance when dispensed by courting males but also allows males to assess the degree of male competition for matings (Mellström, et al.,2009).

Chemical cues play a major role in the process of host selection by parasitoids, a process that has been discriminated into several steps such as habitat location, host location, and host acceptance. Egg parasitoids are known to rely on infochemicals of the adult host stage, e.g., pheromones, rather than cues emitted by the inconspicuous host eggs themselves. Here, we show that three different Trichogramma(Hymenoptera: Trichogrammatidae) species were attracted to the synthetic sex pheromone of the olive, Olea europea L., pest Prays oleae(Bern) (Lepidoptera: Yponomeutidae). In Y-tube olfactometer experiments, we revealed differences in the behavior of four testedTrichogramma strains to different concentrations of the host pheromone. Although wasps of Trichogramma oleae (Voegele & Poitale) (IO47) were significantly attracted to two concentrations of the host pheromone, another strain of the same species (IO24) did not show a response to any offered concentrations. Trichogramma cacoeciaeMarchai females showed greatest attraction toward the pheromone to three of five offered concentrations. Bioassays with Trichogramma bourarachae Pintureau & Babault wasps showed a positive response of the parasitoids to three concentrations of the host pheromone. Detection of the moth sex pheromone may result in an enhanced searching effort by Trichogramma wasps in an area with host eggs and eventually lead to an increased parasitism rate of these eggs (Milonas et al.,2009).

During mating in many butterfly species, males transfer spermatophores that contain anti-aphrodisiacs to females that repel conspecific males. For example, males of the large cabbage white, Pieris brassicae (Lepidoptera: Pieridae), transfer the anti-aphrodisiac, benzyl cyanide (BC) to females. Accessory reproductive gland (ARG) secretion of a mated female P. brassicae that is deposited with an egg clutch contains traces of BC, inducing Brussels sprouts plants (Brassica oleracea var. gemmifera) to arrest certainTrichogramma egg parasitoids. Here, we assessed whether deposition of one egg at a time by the closely related small cabbage white, Pieris rapae, induced B. oleracea var. gemmifera to arrest Trichogramma wasps, and whether this plant synomone is triggered by substances originating from maleP. rapae seminal fluid. We showed that plants induced by singly laid eggs ofP. rapae arrest T. brassicae wasps three days after butterfly egg deposition. Elicitor activity was present in ARG secretion of mated female butterflies, whereas the secretion of virgin females was inactive. Pieris rapae used a mixture of methyl salicylate (MeSA) and indole as an anti-aphrodisiac. We detected traces of both anti-aphrodisiacal compounds in the ARG secretion of mated female P. rapae, whereas indole was lacking in the secretion of virgin female P. rapae. When applied onto the leaf, indole induced changes in the foliar chemistry that arrested T. brassicae wasps  (Fatouros et al.,2009).

Drosophila melanogaster males court mated females significantly less actively than they court virgins. Courtship-inhibiting chemicals (anti-aphrodisiacs) released by mated females when males are present could play a role in controlling the sexual attractiveness of mated females. To test this hypothesis, the attractiveness of intact mated females, which are able to release aversive chemical signals, was compared to that of decapitated mated females, which do not release the signals. By 24 h after mating, reduced female sexual attractiveness was due almost entirely to anti-aphrodisiacs released when males were present. Anti-aphrodisiacs vary between strains, and have been identified as hydrocarbons found primarily on the cuticle of mature males. The quantity of these hydrocarbons on mated females increases when males are present, but the increase is not due to tranfer from the males. When males with radiolabelled cuticular hydrocarbons were paired with mated females, no transfer of label could be detected. Interstrain comparisons showed that males from one strain do not necessarily respond to the anti-aphrodisiac of another, and that male cuticular hydrocarbons may provide a chemical stimulus that induces release of anti-aphrodisiac by mated females. (Scott et al.,1990).

Gregarious mature males of the desert locust (Schistocerca gregaria) emit a courtship-inhibiting pheromone continuously to repel rivals. This signal evokes a strong response from males with recent experience of mature females. However, if males have been female deprived for some time, they start to ignore the pheromone and attempt to usurp females that are guarded by males. The probability and intensity with which males struggle for an occupied mate was found to depend on the time previously spent without a female. This adaptive behaviour is similar to the response to host-marking pheromones in phytophagous insects and parasitoids (Seidelmann et al.,2006).

Males of the beetle Tenebrio molitor produce a volatile sex pheromone which attracts females of the same species. The pheromone level peaks 8 days after emergence and then reaches a plateau. Elimination of endocrine centers by decapitating male adults 24 hr following adult ecdysis did not impair pheromone production. Treatment of decapitated males with juvenile hormone analogues did not make any detectable difference in the levels of pheromone activity. However, undecapitated males treated with juvenile hormone analogue showed a significant increase in pheromone activity when compared with those that had been decapitated and subsequently treated with juvenile hormone analogue. This observation is discussed in the light of published research on the effect of juvenile hormone on pheromone activity of females of T. molitor (Menon et al.,1976).

Phoretic insects utilize other animals to disperse to new environments. We recently discovered how egg parasitoids use an exciting phoretic strategy to reach egg-laying sites of their butterfly hosts. In the laboratory, femaleTrichogramma wasps detect and mount mated female cabbage white butterflies that emit an anti-aphrodisiac pheromone. Hardly any information exists about the natural occurrence of phoresy in wasps of this genus. Therefore, we monitored the presence of phoretic Trichogramma wasps on lepidopteran hosts in the field. Only female wasps were found at low prevalence on six lepidopteran species. Wasps were mostly found on female hosts and mainly on abundant solitary host species. This is the first report of phoretic Trichogramma wasps on butterflies in nature. We suggest that phoresy is only one of several strategies used by these polyphagous egg parasitoids. The evolution of phoresy is discussed in relation to the nutritional ecology of egg parasitoids (Fatouros et al.,2012).

References:

Colin S. Brent and  John A. Byers.2011. Female attractiveness modulated by a male-derived anti-aphrodisiac pheromone in a plant bug. Animal Behaviour, 82:937-943.

Fatouros, Nina E., and Martinus E. Huigens.2012."Phoresy in the field: natural occurrence of Trichogramma egg parasitoids on butterflies and moths."BioControl 57(4): 493-502.

Fatouros, Nina E., Colette Broekgaarden, Gabriella Bukovinszkine'Kiss, Joop JA van Loon, Roland Mumm, Martinus E. Huigens, Marcel Dicke, and Monika Hilker. 2008. Male-derived butterfly anti-aphrodisiac mediates induced indirect plant defense." Proceedings of the National Academy of Sciences105(29):10033-10038.

Fatouros, Nina E., Foteini G. Pashalidou, Wilma V. Aponte Cordero, Joop JA van Loon, Roland Mumm, Marcel Dicke, Monika Hilker, and Martinus E. Huigens.2009. Anti-aphrodisiac compounds of male butterflies increase the risk of egg parasitoid attack by inducing plant synomone production." Journal of chemical ecology 35(11):1373-1381.

Guiraudie‐Capraz, Gaëlle, Dang Ba Pho, and Jean‐Marc Jallon.2007.Role of the ejaculatory bulb in biosynthesis of the male pheromone cis‐vaccenyl acetate in Drosophila melanogaster." Integrative zoology 2,(2): 89-99.

Harraca, Vincent, Camilla Ryne, and Rickard Ignell.2010.Nymphs of the common bed bug (Cimex lectularius) produce anti-aphrodisiac defence against conspecific males." BMC biology 8(1): 121.

Haynes, Kenneth F., Mark H. Goodman, and Michael F. Potter.2010. Bed bug deterrence." BMC biology 8(1): 117.

Huigens, Martinus E., Jozef B. Woelke, Foteini G. Pashalidou, T. Bukovinszky, Hans M. Smid, and Nina E. Fatouros.2010. Chemical espionage on species-specific butterfly anti-aphrodisiacs by hitchhiking Trichogramma wasps." Behavioral Ecology 21(3): 470-478.

Mellström, Helena Larsdotter, and Christer Wiklund.2009. Males use sex pheromone assessment to tailor ejaculates to risk of sperm competition in a butterfly." Behavioral Ecology 20(5):1147-1151.

Menon, Maya.1976. Hormone-pheromone relationships of male Tenebrio molitor."Journal of Insect Physiology 22 (7):1021-1023.

Milonas, P. G., A. F. Martinou, D. Ch Kontodimas, F. Karamaouna, and M. A. Konstantopoulou. 2009.Attraction of different Trichogramma species to Prays oleae sex pheromone." Annals of the Entomological Society of America 102(6):1145-1150.

Schulz, S., Estrada, C., Yildizhan, S., Boppré, M., and Gilbert, L.E. 2008. An antiaphrodisiac in Heliconius melpomene butterflies. J. Chem. Ecol. 34:82-93.

Scott, David, and Larry L. Jackson.1990. The basis for control of post-mating sexual attractiveness by Drosophila melanogaster females." Animal behaviour 40(5): 891-900.

Seidelmann, Karsten.2006.The courtship-inhibiting pheromone is ignored by female-deprived gregarious desert locust males." Biology letters 2(4): 525-527.

Siwicki, Kathleen K., Paul Riccio, Lisa Ladewski, Fabrice Marcillac, Laurence Dartevelle, Stephanie A. Cross, and Jean-François Ferveur.2005.The role of cuticular pheromones in courtship conditioning of Drosophila males."Learning & Memory 12(6): 636-645

Vander Meer, Robert K., Martin S. Obin, Stephen Zawistowski, Kathy B. Sheehan, and Rollin C. Richmond. 1996.A reevaluation of the role of cis-vaccenyl acetate, cis-vaccenol and esterase 6 in the regulation of mated female sexual attractiveness in Drosophila melanogaster." Journal of insect physiology 32(8):681-686.

Zhou, Chuan, Hai Huang, Susy M. Kim, Hsuanwen Lin, Xianglan Meng, Kyung-An Han, Ann-Shyn Chiang, Jing W. Wang, Renjie Jiao, and Yi Rao.2012. Molecular genetic analysis of sexual rejection: roles of octopamine and its receptor OAMB in Drosophila courtship conditioning." The Journal of Neuroscience 32(41): 14281-14287.