Hydrocarbon circulation and colonial signature in Pachycondyla villosa

In ants, both cuticular and postpharyngeal gland (PPG) hydrocarbons (HCs) have been involved in nestmate recognition. However, no detailed comparison is available. A comparative study including also high density lipophorin (HDLp), an internal HC carrier, was therefore undertaken on Pachycondyla villosa. Purified HDLp is an 820 kDa lipoprotein with a density of 1.114 g/ml and two 245 and 80 kDa apo-proteins. Its hydrocarbon profile is very similar with the cuticular one, in agreement with its hydrocarbon carrier function. Conversely, n-alkanes and externally branched monomethylalkanes are markedly decreased in the PPG. According to their physical properties, this suggests that they are involved in waterproofing on the cuticle. The PPG actually contains only internally branched mono-, dimethylalkanes or monomethylalkenes; their greater fluidity is more adequate for chemical communication. The percentages of some of them are statistically not different between the cuticle and PPG. Their mixtures vary with colonies and they may thus be involved in colonial signature. A scheme for hydrocarbon circulation is discussed, involving lipophorin, cuticle, PPG and self-grooming in one individual, a pathway complementary or alternative to the selective delivery by lipophorin in some other insects. HCs are then distributed between nestmates' cuticles through allo-grooming and physical contacts.     

DOES THE VOLATILE HYDROCARBON PROFILE DIFFER BETWEEN THE SEXES: A CASE STUDY ON FIVE APHIDOPHAGOUS LADYBIRDS

Insect hydrocarbons (HCs) primarily serve as a waterproofing cuticular layer and function extensively in chemical communication by facilitating species, sex, and colony recognition. In this study, headspace solid‐phase microextraction is employed for investigating the sex‐specific volatile HC profile of five ladybirds collected from Lucknow, India namely, Coccinella septempunctata (L.), Coccinella transversalis (Fabr.), Menochilus sexmaculatus (Fabr.), Propylea dissecta (Mulsant), and Anegleis cardoni (Weise) for the first time. Major compounds reported in C. septempunctata, C. transversalis, and A. cardoni are methyl‐branched saturated HCs, whereas in M. sexmaculatus, and P. dissecta, they are unsaturated HCs. Other than A. cardoni, both the sexes of the other four ladybirds had similar compounds at highest peak but with statistically significant differences. However, in A. cardoni, which is a beetle with a narrow niche, the major compound in both male and female was different. The difference in volatile HC profile of the sexes of the five ladybirds indicates that gender‐specific differences primarily exist due to quantitative differences in chemicals with only very few chemicals being unique to a gender. This variation in semiochemicals might have a role in behavioral or ecological aspects of the studied ladybirds.     

Pavement Ant Workers (<Emphasis Type="Italic">Tetramorium caespitum</Emphasis>) Assess Cues Coded in Cuticular Hydrocarbons to Recognize Conspecific and Heterospecific Non-Nestmate Ants

Most ants live in closed societies from which non-members are excluded through fighting or ritualized displays to protect colony resources. Nestmate recognition is the process by which ants discriminate nestmate from non-nestmate ants. Ants use cues coded in mixtures of long-chain hydrocarbon compounds on the cuticle as nestmate recognition cues. Pavement ants (Tetramorium caespitum) form conspicuous wars between neighboring colonies that are organized after workers meet and make the decision to fight after assessing nestmate recognition cues. These wars involve thousands of individuals. Fighting is ritualized and few ants die in the process. We identified 24 cuticular hydrocarbon compounds, above 1% in relative abundance, in the profile of pavement ants with chain lengths ranging from 15 to 31 carbon atoms. Cuticular lipids contained, in order of abundance: mono-methyl alkanes (45–56%), n-alkanes (range: 16–40% relative abundance), and alkenes (10–20%), with small or trace amounts of di-methyl, tri-methyl alkanes and fatty acids. Results from behavioral tests show that pavement ants assess information in cuticular hydrocarbon profiles to recognize both conspecific and heterospecfic (Pogonomyrmex occidentalis and Camponotus modoc) non-nestmate ants and that the relative abundance of methyl-branched alkanes and alkenes codes for nestmate status, at least for conspecific interactions. Our data add to a growing body of knowledge about how ants use cuticular hydrocarbon based nestmate recognition cues to prevent the intrusion of non-nestmates in to colony space.     

Cuticular spectra and inter-individual recognition in the slave-making ant Polyergus rufescens and the slave species Formica rufibarbis

Abstract. The relationship between behavioural tests and relative proportions of cuticular components were studied in the slave-making species Polyergus rufescens and the slave and Formica rufibarbis living in either monospecific or mixed colonies. A correlation between the relative proportions of the cuticular products and interindividual recognition exists in each of the two species Polyergus and Formica: Polyergus are fiercely aggressive towards individuals which have different cuticular spectra and originate from a geographically isolated nest. This seems to be true also in the case of Formica living in monospecific colonies. A similar correlation also exists between the two species, which have different cuticular spectra: encounters arranged between them show that free-living Formica are always fiercely aggressive towards Polyergus. The reason why no such correlation seems to exist, however, between Polyergus and Formica when the latter are enslaved and the two species coexist peacefully at the same nest is discussed.     

Do host species evolve a specific response to slave-making ants?

Background

Social parasitism is an important selective pressure for social insect species. It is particularly the case for the hosts of dulotic (so called slave-making) ants, which pillage the brood of host colonies to increase the worker force of their own colony. Such raids can have an important impact on the fitness of the host nest. An arms race which can lead to geographic variation in host defenses is thus expected between hosts and parasites. In this study we tested whether the presence of a social parasite (the dulotic ant Myrmoxenus ravouxi) within an ant community correlated with a specific behavioral defense strategy of local host or non-host populations of Temnothorax ants. Social recognition often leads to more or less pronounced agonistic interactions between non-nestmates ants. Here, we monitored agonistic behaviors to assess whether ants discriminate social parasites from other ants. It is now well-known that ants essentially rely on cuticular hydrocarbons to discriminate nestmates from aliens. If host species have evolved a specific recognition mechanism for their parasite, we hypothesize that the differences in behavioral responses would not be fully explained simply by quantitative dissimilarity in cuticular hydrocarbon profiles, but should also involve a qualitative response due to the detection of particular compounds. We scaled the behavioral results according to the quantitative chemical distance between host and parasite colonies to test this hypothesis.

Results

Cuticular hydrocarbon profiles were distinct between species, but host species did not show a clearly higher aggression rate towards the parasite than toward non-parasite intruders, unless the degree of response was scaled by the chemical distance between intruders and recipient colonies. By doing so, we show that workers of the host and of a non-host species in the parasitized site displayed more agonistic behaviors (bites and ejections) towards parasite than toward non-parasite intruders.

Conclusions

We used two different analyses of our behavioral data (standardized with the chemical distance between colonies or not) to test our hypothesis. Standardized data show behavioral differences which could indicate qualitative and specific parasite recognition. We finally stress the importance of considering the whole set of potentially interacting species to understand the coevolution between social parasites and their hosts.

     

Hydrocarbon distribution and colony odour homogenisation in <Emphasis Type="Italic">Pachycondyla apicalis</Emphasis>

Summary Within and between individuals hydrocarbon (HC)-circulation was studied in Pachycondyla apicalis workers, using radioactive labeling. Newly synthesized HCs occurred both in the PPG and on the epicuticle in appreciable amounts, lesser quantities were found in the crop. The front basitarsal brush contained a greater amount of radiolabeled HCs than could be predicted from its surface area, suggesting preferential secretion to these organs. We propose that the newly synthesized HCs are secreted primarily to the front basitarsal brushes and are thereafter either distributed throughout the body surface, or cleared via the PPG and the alimentary canal.Using labeled HCs as a model, we tracked the time-dependent dispersion of cuticular lipids among 11 workers, one of which was prelabeled for 24 hours. Distribution among the recipients became progressively uniform, reaching near homogenization between 5–10 days. The mean HCs transfer of P. apicalis to the PPG was substantially lower compared to that of Camponotus fellah or Aphaenogaster senilis. In contrast, transfer to the cuticle in this species was superior. We attribute the low transfer to the PPG to the inefficacy of passive body contact characteristic of P. apicalis, as opposed to trophallaxis and/or allogrooming that typify the other two species. The higher occurrence of radiolabeled HCs in P. apicalis cuticle can be attributed to their accumulation in the basitarsal brushes. The impact of cuticular lipid transfer and formation of uniform colony odour, as opposed to the maintenance of an idiosyncratic caste-specific composition, are discussed.Received 5 September 2002; revised 17 January 2003; accepted 10 February 2003.     

Odor diversity decreases with inbreeding in the ant Hypoponera opacior

Reduction in heterozygosity can lead to inbreeding depression. This loss of genetic variability especially affects diverse loci, such as immune genes or those encoding recognition cues. In social insects, nestmates are recognized by their odor, that is their cuticular hydrocarbon profile. Genes underlying hydrocarbon production are thought to be under balancing selection. If so, inbreeding should result in a loss of chemical diversity. We show here that cuticular hydrocarbon diversity decreases with inbreeding. Studying an ant with a facultative inbreeding lifestyle, we found inbred workers to exhibit both a lower number of hydrocarbons and less diverse, that is less evenly proportioned profiles. The association with inbreeding was strong for methyl‐branched alkanes, which play a major role in nestmate recognition, and for n‐alkanes, whereas unsaturated compounds were unaffected. Shifts in allocation strategies with inbreeding in our focal species indicate that these ants can detect their inbreeding level and use this information to adjust their reproductive strategy. Our study is the first to demonstrate that odor profiles can encode information on inbreeding, with broad implications not only for social insects, but for sexual selection and mate choice in general. Odor profiles may constitute an honest signal of inbreeding, a fitness‐relevant trait in many species.     

Ants recognize foes and not friends

Discriminating among individuals and rejecting non-group members is essential for the evolution and stability of animal societies. Ants are good models for studying recognition mechanisms, because they are typically very efficient in discriminating ‘friends’ (nest-mates) from ‘foes’ (non-nest-mates). Recognition in ants involves multicomponent cues encoded in cuticular hydrocarbon profiles. Here, we tested whether workers of the carpenter ant Camponotus herculeanus use the presence and/or absence of cuticular hydrocarbons to discriminate between nest-mates and non-nest-mates. We supplemented the cuticular profile with synthetic hydrocarbons mixed to liquid food and then assessed behavioural responses using two different bioassays. Our results show that (i) the presence, but not the absence, of an additional hydrocarbon elicited aggression and that (ii) among the three classes of hydrocarbons tested (unbranched, mono-methylated and dimethylated alkanes; for mono-methylated alkanes, we present a new synthetic pathway), only the dimethylated alkane was effective in eliciting aggression. Our results suggest that carpenter ants use a fundamentally different mechanism for nest-mate recognition than previously thought. They do not specifically recognize nest-mates, but rather recognize and reject non-nest-mates bearing odour cues that are novel to their own colony cuticular hydrocarbon profile. This begs for a reappraisal of the mechanisms underlying recognition systems in social insects.     

Interspecific recognition in Chilean parabiotic ant species

Summary In Chile, Camponotus morosus and Solenopsis gayi sometimes co-inhabit a single nest, seemingly in a parabiotic association. To elucidate the nature of this association we conducted behavioural tests that measured aggression between homo- and allospecific ants. These tests revealed that C. morosus was aggressive towards alien conspecific and allospecific ants, but tolerated allospecific individuals from the same parabiotic society as well as allospecific individuals from a different parabiotic colony. In contrast S. gayi was much more tolerant towards alien ants whether homo- or allospecific and irrespective of their colony of origin, parabiotic or non-parabiotic.Chemical analyses showed that each species possess a distinct cuticular hydrocarbons profile. Moreover, each species tended to keep its specific profile even when living in association with the other species, in spite of very little acquired allospecific chemicals in C. morosus, dismissing chemical mimicry as the basis of the peaceful co-existence. We hypothesise that the switch from aggression to tolerance as a consequence of parabiotic association exhibited by C. morosus is due to a familiarisation as well as memorisation of the allospecific colonial odour. The finding that the parabiotic C. morosus was tolerant to S. gayi, even if they originated from a non-parabiotic nest points to an odour generalisation ability in this species.Received 12 July 2002; revised 15 January and 11 April 2003; accepted 23 April 2003.     

Myrmecophily in Hesperiidae. The case of Vettius tertianus in ant gardens

The larvae of the hesperiid butterfly Vettius tertianus develop by eating the leaves of Aechmea mertensii, a bromeliad epiphyte restricted to ant gardens. The relationships between ants and V. tertianus larvae highlight the preferential association of the caterpillars with Pachycondyla goeldii (Ponerinae), an ant-garden initiator. The oviposition strategy of V. tertianus may thus imply the identification of the inhabiting ant species and not only the identification of the host plant. The caterpillars neither provide secretions to the ants, nor possess defensive devices (i.e. hairs or appendices) against ants. Their activity rhythm does not isolate them from foraging workers of P. goeldii and their shelters are also attainable by the ants. Moreover, as the cuticular lipid profiles of V. tertianus larvae are clearly different from those of the ants and also from the leaf-surface of A. mertensii, acceptance is not due to mimicry between larvae and plants or ants. However, the caterpillars deposit, on the leaf they eat, silk containing a mixture of substances very similar to those found on their own cuticle. No interaction with ants was recorded during observations, even though the ant gardens were patrolled by numerous P. goeldii individuals during their activity period. But when confronted with the caterpillar, none of the tested ant species reacted aggressively. These results suggest the existence of compounds, other than cuticular lipids, responsible for the absence of aggressiveness in the ants. The case of V. tertianus is relatively new as myrmecophily within Hesperiidae has been described only once. Moreover, it preferentially involves a member of the Ponerinae, a subfamily in which interactions with other arthropods are exceptional.     

Rapid evolution of cuticular hydrocarbons in a species radiation of acoustically diverse Hawaiian crickets (Gryllidae: trigonidiinae: Laupala)

Understanding the origin and maintenance of barriers to gene exchange is a central goal of speciation research. Hawaiian swordtail crickets (genus Laupala) represent one of the most rapidly speciating animal groups yet identified. Extensive acoustic diversity, strong premating isolation, and female preference for conspecific acoustic signals in laboratory phonotaxis trials have strongly supported divergence in mate recognition as the driving force behind the explosive speciation seen in this system. However, recent work has shown that female preference for conspecific male calling song does not extend to mate choice at close range among these crickets, leading to the hypothesis that additional sexual signals are involved in mate recognition and premating isolation. Here we examine patterns of variation in cuticular lipids among several species of Laupala from Maui and the Big Island of Hawaii. Results demonstrate (1) a rapid and dramatic evolution of cuticular lipid composition among species in this genus, (2) significant differences among males and females in cuticular lipid composition, and (3) a significant reduction in the complexity of cuticular lipid profiles in species from the Big Island of Hawaii as compared to two outgroup species from Maui. These results suggest that behavioral barriers to gene exchange in Laupala may be composed of multiple mate recognition signals, a pattern common in other cricket species.     

Intraspecific nestmate recognition in two parabiotic ant species: acquired recognition cues and low inter-colony discrimination

Parabiotic ants—ants that share their nest with another ant species—need to tolerate not only conspecific nestmates, but also nestmates of a foreign species. The parabiotic ants Camponotus rufifemur and Crematogaster modiglianii display high interspecific tolerance, which exceeds their respective partner colony and extends to alien colonies of the partner species. The tolerance appears to be related to unusual cuticular substances in both species. Both species possess hydrocarbons of unusually high chain lengths. In addition, Cr. modiglianii carries high quantities of hereto unknown compounds on its cuticle. These unusual features of the cuticular profiles may affect nestmate recognition within both respective species as well. In the present study, we therefore examined inter-colony discrimination within the two parabiotic species in relation to chemical differentiation. Cr. modiglianii was highly aggressive against workers from alien conspecific colonies in experimental confrontations. In spite of high inter-colony variation in the unknown compounds, however, Cr. modiglianii failed to differentiate between intracolonial and allocolonial unknown compounds. Instead, the cuticular hydrocarbons functioned as recognition cues despite low variation across colonies. Moreover, inter-colony aggression within Cr. modiglianii was significantly influenced by the presence of two methylbranched alkenes acquired from its Ca. rufifemur partner. Ca. rufifemur occurs in two varieties (‘red’ and ‘black’) with almost no overlap in their cuticular hydrocarbons. Workers of this species showed low aggression against conspecifics from foreign colonies of the same variety, but attacked workers from the respective other variety. The low inter-colony discrimination within a variety may be related to low chemical differentiation between the colonies. Ca. rufifemur majors elicited significantly more inter-colony aggression than medium-sized workers. This may be explained by the density of recognition cues: majors carried significantly higher quantities of cuticular hydrocarbons per body surface.     

Divergent mechanisms for water conservation in Drosophila species

The role of melanization and cuticular lipids in water conservation has been studied in many Drosophila species (Diptera: Drosophilidae). Nevertheless, a comparative approach to larval and adult stages of ecologically diverse, wild Drosophila species is still required. Based upon abdominal cuticular melanization patterns, wild‐caught Drosophila species were categorized as (1) melanic, (2) fixed‐melanic, or (3) non‐melanic. At the interspecific level, the ecological significance of melanization and cuticular lipids was determined by the inverse association of melanization and cuticular water loss in melanic species, and of cuticular lipids and cuticular water loss in fixed‐melanic and non‐melanic species. Interestingly, higher amounts of cuticular lipids were also evident in fixed as well as non‐melanic species, as compared to melanic species at larval stages, which is consistent with their differences in reduced water loss rates. Moreover, fixed‐melanic and non‐melanic species exhibited comparatively higher (ca. 1.8–2.0 fold) desiccation resistance. Thus, cuticular lipids provide a better waterproofing mechanism than melanization. Furthermore, acclimation to dehydration stress in adults improved desiccation resistance in melanic species, whereas such effects were lacking in fixed‐melanic and non‐melanic species. However, there were no changes in cuticular components as a consequence of desiccation acclimation. Thus, our results indicate that melanic, fixed‐melanic, and non‐melanic Drosophila species differ in the evolved physiological mechanisms of water conservation to adapt to dry conditions.     

The importance of cuticular permeability, osmolyte production and body size for the desiccation resistance of nine species of Collembola

Euedaphic collembolans have recently been shown to actively regulate internal osmotic pressure by means of sugars and polyols in response to desiccation. In contrast, studies of cuticular permeability have shown that some, especially epedaphic, species of collembolans may primarily rely on a low cuticular permeability to survive desiccation. To elucidate to what extent these strategies are important for desiccation resistance, the survival of 7-day acute desiccation stress (LRH(50)), the cuticular water conductance constant and osmolyte production were investigated in nine species of collembolans, covering euedaphic, hemiedaphic and epedaphic species. The LRH(50) values ranging from 98.8% to 95.2% RH showed no correlation with the vertical distribution of species, since both the highest and lowest values were found in epedaphic species. The water conductance varied from 698+/-141 to 41+/-13 microg h(-1) cm(-2) mmHg(-1) and showed good agreement with the vertical distribution of species in their natural habitats. Modelling the drying curves showed that, in addition to cuticular permeability and osmolyte production, body size also plays an important role in the survival of short-term severe desiccation stress. Furthermore, the model pointed to the need for behavioural responses to desiccation, particularly in epedaphic species. Thus, in keeping with expected humidity regimes in their respective microhabitats, euedaphic species rely on small body size, high cuticular permeability and the ability to actively regulate the osmotic pressure of their body fluids, hemiedaphic species have similar strategies but with reduced cuticular permeability, whereas in epedaphic species, active regulation of osmotic pressure is replaced by combinations of greatly reduced cuticular permeability or greatly reduced surface area to volume ratio combined with behavioural responses to desiccation.     

Cleptoparasites, social parasites and a common host: Chemical insignificance for visiting host nests, chemical mimicry for living in

Social insect colonies contain attractive resources for many organisms. Cleptoparasites sneak into their nests and steal food resources. Social parasites sneak into their social organisations and exploit them for reproduction. Both cleptoparasites and social parasites overcome the ability of social insects to detect intruders, which is mainly based on chemoreception. Here we compared the chemical strategies of social parasites and cleptoparasites that target the same host and analyse the implication of the results for the understanding of nestmate recognition mechanisms. The social parasitic wasp Polistes atrimandibularis (Hymenoptera: Vespidae), and the cleptoparasitic velvet ant Mutilla europaea (Hymenoptera: Mutillidae), both target the colonies of the paper wasp Polistes biglumis (Hymenoptera: Vespidae). There is no chemical mimicry with hosts in the cuticular chemical profiles of velvet ants and pre-invasion social parasites, but both have lower concentrations of recognition cues (chemical insignificance) and lower proportions of branched alkanes than their hosts. Additionally, they both have larger proportions of alkenes than their hosts. In contrast, post-invasion obligate social parasites have proportions of branched hydrocarbons as large as those of their hosts and their overall cuticular profiles resemble those of their hosts. These results suggest that the chemical strategies for evading host detection vary according to the lifestyles of the parasites. Cleptoparasites and pre-invasion social parasites that sneak into host colonies limit host overaggression by having few recognition cues, whereas post-invasion social parasites that sneak into their host social structure facilitate social integration by chemical mimicry with colony members.     

Genetics, behaviour and chemical recognition of the invading ant Pheidole megacephala

Introduced species often become ecologically dominant, displacing native species and posing a serious threat to ecosystem function and global biodiversity. Ants are among the most widespread and damaging alien species; introductions are often accompanied by population-level behavioural and genetic changes contributing to their success. We investigated the genetic structure, chemical profile and nestmate recognition in introduced populations of the invasive big-headed ant, Pheidole megacephala, in Australia. Behavioural analyses show that workers are not aggressive towards conspecifics from different nests, even at large geographical scales (up to 3000 km) and between populations encompassing a wide range of environmental conditions. By contrast, interactions with workers of other species invariably result in agonistic behaviours. Genetic analyses reveal that populations have low genetic diversity. No genetic differentiation occurs among nests of the same population; differentiation between populations, though significant, remains weak. Chemical analyses indicate that cuticular lipids are similar between colonies of a population, and that differentiation between populations is low. Altogether, these results indicate that the big-headed ant P. megacephala forms a large unicolonial population across northern/eastern Australia.     

Male pheromone polymorphism and reproductive isolation in populations of Drosophila simulans

The dominant cuticular hydrocarbons (HC) in Drosophila simulans are 7‐tricosene (7‐T) and 7‐pentacosene (7‐P). The 7‐T is the major HC in East Africa and in other continents. In West Africa, D. simulans is very rare and displays 7‐P as the major compound. We studied three D. simulans strains from Egypt (Eg), Sao‐Tome (ST), and Cameroon (Cam), with 7‐T, intermediary or 7‐P phenotypes. HC profiles of ST and Cam female differed slightly from corresponding male profiles; females had more 7‐T and less 7‐P. Varying temperature affected all HCs (even those with 27 and 29 carbons)‐not just 7‐T and 7‐P; there was no clear relationship between HC phenotype and resistance to desiccation. We report reproductive isolation between Eg and ST and Eg and Cam (but not between ST and Cam), which is due to Eg and Cam female preferences for their own males. In conclusion, our findings do support divergence of D. simulans populations from West Africa for both pheromonal profile and mating preference.     

Thief ants have reduced quantities of cuticular compounds in a ponerine ant, Ectatomma ruidum

Abstract. Workers of a tropical ponerine ant, Ectatomma ruidum (Roger), exhibit a system of intercolonial thievery for food; thief ants enter conspecific colonies, intercept food, and carry it to their own colony. We analysed thief ants, ants from the thief's colony, and ants from the colony being robbed to determine if changes in cuticular profiles could facilitate entry by thieves into a target colony. Thief ants have significantly lower total quantities of dichloromethane-soluble cuticular compounds than non-thieves. The reduction in cuticular compounds on thieves suggests that thievery is facilitated by inhibition of either synthesis or acquisition of its home colony's recognition cues. Five of the fifteen compounds differed significantly in their relative proportion among colonies. Principal components analysis lends support to the hypothesis that both inhibition of a thief's home colony cues and acquisition of its target colony's cues play a role in successful thievery.     

Genetic study of the production of sexually dimorphic cuticular hydrocarbons in relation with the sex-determination gene transformer in Drosophila melanogaster

In Drosophila melanogaster, the main cuticular hydrocarbons (HCs) are some of the pheromones involved in mate discrimination. These are sexually dimorphic in both their occurrence and their effects. The production of predominant HCs has been measured in male and female progeny of 220 PGa14 lines mated with the feminising UAS-transformer transgenic strain. In 45 lines, XY flies were substantially or totally feminised for their HCs. Surprisingly, XX flies of 14 strains were partially masculinised. Several of the PGa14 enhancer-trap variants screened here seem to interact with sex determination mechanisms involved in the control of sexually dimorphic characters. We also found a good relationship between the degree of HC transformation and GAL4 expression in oenocytes. The fat body was also involved in the switch of sexually dimorphic cuticular hydrocarbons but its effect was different between the sexes.