Polyandrous Groups Research Articles

Factors Influencing Copulation Duration in Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae).

The gregarious ectoparasitic beetle Dastarcus helophoroides (Fairmaire) is considered a primary biocontrol agent for controlling several cerambycid pests in East Asian countries. A thorough study of reproductive behavior is a prerequisite for the mass production of natural insect predators. Nonetheless, little attention has been given to this ectoparasitic beetle. We performed a series of trials to assess whether the adult copulation duration, a key behavioral trait, is differentially influenced by physiological and ecological factors, including body size, mating history, kinship, sex ratio, mating sequence, feeding status, ambient temperature, photoperiod, and time of day. Additionally, the effect of the copulation duration on the reproductive output of this beetle was also investigated. The results indicated that the copulation duration varied considerably, ranging from 1.12 min to 16.40 min and lasting for an average of 9.11 ± 0.12 min. Females with longer copulations laid more eggs and had a greater proportion of eggs hatched. Medium-sized individuals copulated significantly longer than small- and large-sized individuals. The copulation durations were significantly longer when both sexes experienced an asymmetric mating history than when both sexes experienced a symmetric mating history. Inbred couples copulated significantly longer than outbred couples. In terms of the adult sex ratio, increasing the density of females (polygamous group) or males (polyandrous group) led to significantly longer copulation durations than those in the monogamous group. The copulation durations gradually decreased with increasing the mating sequence and temperature. Food-absence couples copulated significantly longer than food-presence couples. The mean copulation duration of the scotophase was significantly longer than that of the photophase. These results demonstrate that all of the analyzed factors emerge as important factors influencing the copulation duration, ultimately affecting the reproductive outputs in this ectoparasitic beetle.

Social polyandry among siamangs: the role of habitat quality

In species where females do not associate spatially with other females, males usually range over an area including the home ranges of multiple females or defend the home range of one female. Nevertheless, social polyandry (multimale–unifemale grouping) occurs in some species. We examine an ecological constraints model relating habitat quality to facultative social polyandry in siamangs, Symphalangus syndactylus, by testing predictions of two hypotheses: (H1) variation in the size and density of important food trees affects the size of siamang home ranges and areas of exclusive use; (H2) socially polyandrous groups benefit from cooperative defence of the home range and area of exclusive use. Crown volume/ha of freestanding or strangler figs (Ficus), the most important siamang food, was negatively related to the size of the home range but not to the size of the area of exclusive use. Density and crown volume/ha of the second-most important plant food, Dracontomelon dao, was not related to the size of the home range or to the size of the area of exclusive use. Multimale groups had larger home ranges and areas of exclusive use than unimale groups, and the home ranges and areas of exclusive use of multimale groups encompassed more freestanding or strangling figs than those of unimale groups. Models of home range size including fig abundance (density or crown volume/ha) and the number of males as predictor variables suggested that multimale groups have larger home ranges than predicted by the relationship between fig abundance and home range size alone. While some other facultatively polyandrous species have larger home ranges in areas of poorer habitat quality, our results suggest a more complex situation for siamangs at our study site. Specifically, the density of large figs may constrain siamang ranging patterns, but multimale groups live in home ranges with more figs than those of unimale groups. Our results suggest that multimale groups may defend higher-quality territories than unimale groups.

Pre- and postcopulatory sexual selection favor aggressive, young males in polyandrous groups of red junglefowl.

A challenge in evolutionary biology is to understand the operation of sexual selection on males in polyandrous groups, where sexual selection occurs before and after mating. Here, we combine fine-grained behavioral information (>41,000 interactions) with molecular parentage data to study sexual selection in replicated, age-structured groups of polyandrous red junglefowl, Gallus gallus. Male reproductive success was determined by the number of females mated (precopulatory sexual selection) and his paternity share, which was driven by the polyandry of his female partners (postcopulatory sexual selection). Pre- and postcopulatory components of male reproductive success covaried positively; males with high mating success also had high paternity share. Two male phenotypes affected male pre- and postcopulatory performance: average aggressiveness toward rival males and age. Aggressive males mated with more females and more often with individual females, resulting in higher sexual exclusivity. Similarly, younger males mated with more females and more often with individual females, suffering less intense sperm competition than older males. Older males had a lower paternity share even allowing for their limited sexual exclusivity, indicating they may produce less competitive ejaculates. These results show that-in these populations-postcopulatory sexual selection reinforces precopulatory sexual selection, consistently promoting younger and more aggressive males.

Offspring loss after male change in wild siamangs: the importance of abrupt weaning and male care.

Infanticide by males is assumed to promote permanent male-female associations, although its importance for social monogamy is still debated. We examined the consequences of male membership change in the largest socially monogamous primate, the siamang (Symphalangus syndactylus), a species that also forms polyandrous groups and where males may provide offspring care. We examine (a) the potential risk of infanticide by documenting changes in female-offspring relationships following male change, expecting abrupt weaning; and (b) the potential importance of male care and polyandry for offspring survival. We witnessed four male changes at Way Canguk Field Station (Indonesia) in groups where the youngest offspring was estimated to be about 2years of age. We quantified aspects of mother-offspring relationships (interindividual distance, body contact, and nipple contact) and estimated the proportion of time being carried during travel (August 2007-April 2009). In the two groups into which new males immigrated, offspring were weaned abruptly, suggesting infanticide by males as a potential risk. Even though no attacks on infants by males were witnessed, both infants disappeared shortly after the male change. Another infant disappeared after its main carrier (a male) emigrated. Conversely, in a group where the resident subordinate male replaced the dominant male, the offspring experienced no change in care and survived the transition. These findings suggest that male immigration in hylobatids increases mortality risk for infants, emphasize the importance of offspring care, and cast doubts on prior classifications of 2-year-old siamangs as independently traveling individuals.

Conflict and cooperation over sex: the consequences of social and genetic polyandry for reproductive success in dunnocks.

Conflict and cooperation within and between the sexes are among the driving forces that lead to the evolution of mating systems. Among mating strategies, female genetic polyandry and male reproductive cooperation pose challenging evolutionary questions regarding the maintenance of systems where one sex suffers from reduced fitness. Here, we investigate the consequences of social and genetic polyandry for reproductive success of females and males in a population of the dunnock, Prunella modularis. We show that female multiple mating ameliorates the negative effects of inbreeding. We, however, found little evidence that females engage in extra-group (pair) mating with less related or more heterozygous males. Breeding in socially polyandrous groups reduced the amount of paternity lost to extra-group males, such that, on average, cobreeding and monogamous males fledged a similar number of young. Importantly, c. 30% of cobreeding male dyads were related, suggesting they could gain indirect fitness benefits. Taken together, cobreeding males achieve equivalent reproductive success to monogamous counterparts under most circumstances. Our study has revealed unexpected complexities in the variable mating system of dunnocks in New Zealand. Our results differ from the well-known Cambridge dunnock study and can help our understanding of the evolution and maintenance of various breeding systems in the animal kingdom.

Dominance relationships among siamang males living in multimale groups.

Intense intolerance among males is considered to be an important mechanism maintaining the uni-male organization traditionally attributed to socially monogamous gibbons. Long-term field work, however, has revealed the existence of stable, socially polyandrous groups in at least two populations, raising questions about the mechanism that allows two adult males to co-reside in the same group. I collected 21 months of behavioral data on 7 two-male groups of wild siamangs (Symphalangus syndactylus) in southern Sumatra (Indonesia) to test the hypothesis that dominance relationships regulate the interactions of adult male siamangs and ultimately facilitate multi-male social groups. A dominant male could clearly be identified in each dyad, based on a consistent direction of agonistic interactions, displacements and the maintenance of an advantageous position in the canopy. Males identified as dominant enjoyed greater social access to the resident female and monopolized copulations. These results suggest that gibbons possess the psycho-social flexibility to regulate intra-sexual aggression and live in multi-male social units under certain social conditions. I discuss the effects that relatedness between males and female choice have in determining this grouping pattern, and the role of male intolerance in the maintenance of primate mating systems.

Atypical, ventro-ventral copulation position in aphids of the genus Stomaphis Walker, 1870 (Insecta, Hemiptera)

Firm matching of genitals during copulation is of critical importance to effective insemination and thus, gene flow. During the evolution of insects, an effective position during copulation promoted higher fecundity through control over the act of mating or elimination of competitors. Usually during insect copulation, either twisting or flexing of the male abdomen occurs, and genitals remain symmetrically or asymmetrically disposed following changes in the mating position. However, it is always the dorsal side of the male genitalia that makes contact with the ventral side of female abdomen. Here we present the unusual case of a ‘belly-to-belly’ copulation, with symmetrically positioned male genitals and no twisting of the abdomen. During the mating of two species in the Stomaphis genus of large, tree dwelling aphids, the dwarfish male is attached to the underside of the female, with the ventral part of its genitals contacting the ventral part of female abdomen, and the aedeagus effectively inserted into the female genital organs. Interestingly, congeneric species do not exhibit this sort of mating, but differences in the genital plates of females, between species, may play an important role. These observations raise many questions concerning the possible dominant role of the female during mating and later, during mate guarding by male, which can lead to monandry in this generally polyandrous group of insects. It is possible that this sort of mating is either an adaptation to the competitive behaviour of other males or a consequence of the obligatory mutualistic relationship with ants, and the adaptation to specialised ecological niches enforced by this relationship. If ants do influence the mating habits of Stomaphis then it is possible that speciation in this group of insects, and phytophagous insects generally, is partially driven by their relationship with ants.

Breeding Biology and Variable Mating System of a Population of Introduced Dunnocks (Prunella modularis) in New Zealand

Species with variable mating systems provide a unique opportunity to investigate whether females receive direct fitness benefits from additional male partners. The direct benefits provide an obvious explanation for why females would breed polyandrously, in a situation where males clearly do not attain their optimal reproductive success. Evidence for these direct benefits is, however, mixed. Here, we present a detailed study of the breeding biology of the dunnock, Prunella modularis, which inform an investigation into the effects of the social mating system on the reproductive success in a population of dunnocks in Southern New Zealand. We studied 80 different social groups over the course of three breeding seasons. Dunnocks in our population presented a variable mating system, with socially monogamous (45%), socially polyandrous (54%) and socially polygynandrous (1%) groups being observed in the same breeding season. We did not observe any polygynous social units in our study period although polygyny exists in the population. We found little difference in the numbers of eggs laid, and egg volume between monogamous and polyandrous nests. However, polyandrous groups had better hatching and fledging success than monogamous groups (composite d = 0.385, 95% CI: 0.307 to 0.463). Overall our results support the notion that polyandry is beneficial for females.

Effects of social status and stress on patterns of gastrointestinal parasitism in wild white‐handed gibbons (Hylobates lar)

Although gibbons (family Hylobatidae) are typically monogamous, polyandrous groups occur regularly. Stress associated with elevated intragroup competition among males in polyandrous groups may increase susceptibility to infectious disease. To better understand this interplay, as well as to provide the first comprehensive assessment of parasitism in free-ranging gibbons, we characterized the richness of gastrointestinal parasites and examined their prevalence in males from 14 groups (10 pair-living, 4 multi-male) of white-handed gibbons (Hylobates lar) at Khao Yai National Park, Thailand. From September 2008 to May 2009, 324 fecal samples were collected from 23 individually recognizable male gibbons and screened for gastrointestinal helminths and protozoa after isolation via fecal floatation, sedimentation, and immunofluorescent antibody detection. A total of 10 parasite species recovered, including seven nematodes, two protozoans, and one trematode. Parasite richness and species-specific prevalence were examined relative to social organization (pair-living vs. multi-male), male status (primary vs. secondary), age (subadult, adult, senior), fecal glucocorticoid levels, and time of the year. No relationship was found between parasite richness and sociodemographic or physiological factors. Similarly, prevalence of infection with parasite species was not associated with the majority of sociodemographic factors; however, Ternidens sp. and Balantidium coli varied seasonally and Trichuris sp. decreased with increasing age. Moreover, observational data suggest that competition is low in this gibbon population, and our findings are consistent with those observations in that cooperative defense may offset stress and reduce susceptibility to infection.

To Be a Dominant Female: A Hard Way to Go

Copyright: © 2012 da Silva Mota MT. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Reproduction is a very demanding task for any species. It is a combination of mating effort (time and energy spent searching and attracting sexual partners) and parental effort (time and energy invested in infant care) which are the main determinants of male and female reproductive success [1]. As an example, I am going to focus this editorial on a small primate endemic to Brazil, the common marmoset, Callithrix jacchus. They live in extended family groups with 5 to 17 individuals that may or may not be genetically related [2,3]. Reproduction is restricted to a single pair but polygynous and polyandrous groups have been also reported [4,5]. Concerning adult females, social hierarchy determines their reproductive status that competes for breeding positions and mating opportunities. The competition can be expressed by behavioral and physiological mechanisms such as intrasexual aggression, infanticide, inadequate alloparental care, puberty delay and ovulatory suppression [6]. Adult female usually gives birth to twins that are around 15% of the mother’s weight which need full time care. They are cooperative breeders and all members of the social group are potential helpers from the first day after the birth of infants [7]. It is important to note that the distribution of care varies between individuals, with adult males being the main caretakers [8]. Their participation in infant care and the number of infants being carried change prolactin levels which may be related to physical effort following carrying behavior [9]. Thus, the participation of helpers is essential to reproductive success and influence the hormonal profile of caretakers.

Monogamous and Polyandrous Mating Systems: Effects on Growth and Haematological Indices of The Albino Rat

Thirty albino rats (20 males and 10 females) of the Wistar strains were used in a sixteen week trial to evaluate the effects of monogamous and polyandrous groupings on growth and haematological variables. The monogamous group (MG) comprised 5 males and 5 females while the polyandrous group(PG) was made up of 15 males and 5 females. Final weights of the monogamous and polyandrous groups were 222.11g and 212.33g with a total weight change of 151.83g and 148.77g respectively. The final weight of males in the two groups gave statistically significant (P 0.05) values for red blood corpuscles(RBC), white blood corpuscles(WBC), Hb.conc., mean corpuscular haemoglobin concentration(MCHC), %lymphocyte and %monocyte than the polyandrous males(PM). The PM on the other hand gave higher but insignificant values for mean corpuscular haemoglobin(MCH), mean corpuscular volume(MCV), %eosinophil and %basophil than in the MM. Higher values (P 0.05) in the PF. Values for %monocyte and Hb.conc. showed slight (P> 0.05) increase among the MF. It may be concluded that monogamy promotes better weight change(growth) in males while polyandry influences better weight change in the female rats. Also monogamous groupings could result in increased PCV, Hb.conc. and %neutrophil content of the blood while polyandry could lead to a high % blood lymphocyte when the sexes are taken together. The increased circulating leucocytes observed in the polyandrous females could be as a result of their physiological adjustment to social stress.

Male care of infants in a siamang (Symphalangus syndactylus) population including socially monogamous and polyandrous groups

While male parental care is uncommon in mammals, siamang (Symphalangus syndactylus) males provide care for infants in the form of infant carrying. I collected behavioral data from a cohort of five wild siamang infants from early infancy until age 15–24 months to identify factors affecting male care and to assess the consequences of male care for males, females, and infants in a population including socially monogamous groups and polyandrous groups. There was substantial variation in male caring behavior. All males in polyandrous groups provided care for infants, but males in socially monogamous groups provided substantially more care than males in polyandrous groups, even when the combined effort of all males in a group was considered. These results suggest that polyandry in siamangs is unlikely to be promoted by the need for “helpers.” Infants receiving more care from males did not receive more care overall because females compensated for increases in male care by reducing their own caring effort. There was no significant relationship between indicators of male–female social bond strength and male time spent carrying infants, and the onset of male care was not associated with a change in copulation rates. Females providing more care for infants had significantly longer interbirth intervals. Male care may reduce the energetic costs of reproduction for females, permitting higher female reproductive rates.

Influences of mating groups on the reproductive success of the Southern Sichuan Red Panda (Ailurus fulgens styani)

The reproduction of female red pandas under three different husbandry conditions (monogamy, polygamy, and polyandry) was studied at the Chengdu Research Base for Giant Panda Breeding, and Chengdu Zoological Park, China. We monitored the fecal steroid profiles of seven females by radioimmunoassay in order to understand how the different mating groupings affect the animals' reproductive success. Of the seven females studied, all gave birth except the one that was kept in the polyandrous group. Although fecal estradiol metabolites exhibited several peaks during estrus, only one coincided with mating behavior. Fecal progesterone metabolites did not display a sustained rise in the absence of mating behavior, even though estradiol displayed a peak of secretion. This suggests that the red panda may be an induced ovulator. During gestation, fecal progesterone metabolites were maintained at a comparatively high level, and were much higher than those of nonpregnant females. The female in the polyandrous group showed an abnormal estradiol metabolite profile, with a level that was four to five times higher than those of the females in the polygynous groupings. It was observed that this female always escaped and hid in the trees to avoid courtships with males, and did not give birth. This phenomenon suggests that polyandrous groupings may be unsuitable for successful reproduction in captivity. Zoo Biol 24:169–176, 2005. © 2005 Wiley-Liss, Inc.

EFFECTS OF HOST SOCIALITY ON ECTOPARASITE POPULATION BIOLOGY

Theory predicts a positive relationship between parasite infection intensity and host density. However, this generalization is complicated in natural systems by differences in life history among parasite taxa, e.g., transmissibility. Accordingly, predictions relating host density to parasite load should be specific to each parasite taxon. To illustrate this, we studied parasites that differed greatly in life history in the context of the Galapagos hawk's (Buteo galapagoensis) variably cooperative mating system. Two louse (Phthiraptera) species were collected: Colpocephalum turbinatum (Amblycera), with 53 host species, and Degeeriella regalis (Ischnocera), with 10 host species, although B. galapagoensis was the only known Galapagos host. Sixty territorial adult male hawks from 26 groups of 1-6 males were quantitatively sampled for lice. Average abundance and intensity of C. turbinatum but not D. regalis were significantly larger in large groups of hawks than small groups. Males from the same polyandrous group harbored significantly correlated abundances of C. turbinatum but not D. regalis. Prevalence, average abundance, and intensity of C. turbinatum were significantly higher than D. regalis. These are the first results to demonstrate significant differences in a suite of population responses between these louse suborders in the context of host sociality.

Behavioral and Endocrine Responses in Male Marmosets to the Establishment of Multimale Breeding Groups: Evidence for Non-monopolizing Facultative Polyandry

Studies of wild callitrichids provide conflicting evidence regarding polyandrous groups. One perspective supports a monopolizing breeding strategy on the part of one male, while the alternative perspective suggests that polyandry does not lead to a breeding monopoly. We tested the hypotheses in male marmosets (Callithrix kuhlii) with 5 polyandrous groups composed of related/familiar males as our attempts to establish polyandrous groups of unrelated/familiar males failed. We monitored male social and sexual behavior and urinary testosterone (T) and cortisol (CORT) across the first 80 days of group formation and contrasted them with similar measures in males housed in monogamous groups. We also examined the same measures across the females' ovulatory cycles for polyandrous males. We found little evidence that males in polyandrous groups exercised a mating monopoly over the female and no evidence for overt competition between polyandrous males. We found 2 behavioral differences: polyandrous males were less often in proximity and copulated more often with the female than monogamous males did. Our findings suggest that the males in newly-formed groups of marmosets do not monopolize breeding and social behavior with the female. This appears to be the case for 3 reasons. First, males may use sperm competition rather than overt competition. Secondly, it may take longer for relationships to develop between the female and the males in polyandrous groups versus in monogamous groups. Thirdly, the cost of infant care is sufficiently high to demand that group members get along when groups are small and reproductive benefits are shared.

The relative influence of prey abundance and co-breeders on the reproductive performance of polyandrous Pale Chanting-goshawks

This study investigates if the reproductive performance of polyandrous Pale Chanting-goshawks, Melierax canorus, is governed by the abundance of dominant rodent-prey species or a co-breeding male participating fully in prey being delivered to the female and young. Polyandrous trios in prey-rich habitat, the only habitat where these trios occurred, failed to produce more offspring than monogamous pairs, but attempted more second broods in years of high prey abundance. The higher the prey-delivering rates at the nesting sites by either one monogamous male or two polyandrous males (combined effort), the higher the proportion of time their females spent in close proximity to the nest. Since there were no significant differences between the body masses of nestlings fledged by polyandrous and monogamous groups, higher delivery rates relieved females from away-from-the-nest hunting duties and permitted them to feed on prey not fed to offspring. Although breeding in polyandrous trios held fitness benefits for females, e.g. to accumulate the necessary body reserves for laying a second clutch in years of high prey abundance, it is still not clear how males benefited. The reproductive performance of each group was strongly linked to the abundance of the dominant, otomyine rodent prey (Otomys unisulcatus and Parotomys brantsii) and it was therefore prey abundance, and not the number of males delivering prey to the female and nestlings at each nesting site, that controlled the reproductive performance of cooperative-breeding Pale Chanting-goshawks.

Variability in adult group compositions of a prosimian primate

Many species fall into specific mating-system categories, and that category is usually associated with a suite of behavioral and morphological characteristics. Several lemur species, including Propithecus diadema edwardsi, have been labeled "idiosyncratic" because variation in socionomic sex ratios among groups is consistent with wide variation in social structure. We used several hypotheses founded in behavioral ecology to assess variability in P. d. edwardsi. First we examined 46 group-mating seasons to quantify variability. We then tested predictions that the number of males per group would increase as the number of adult females increased, and the number of males would increase as female mating synchrony increased. Examining variation in offspring survival relative to the number of adult males in a group may tell us which composition is likely to persist into the future, so we also hypothesized that as the number of males in a group increased, fertility and offspring survival would increase. We found an equal distribution of polygynous, polygynandrous, pairs, and polyandrous groups. Furthermore, female distribution and mating synchrony did not predict the number of males, and offspring survival was not correlated with the number of males. Since infants survived equally well in groups of all compositions, sifakas experienced no pressure to maintain a particular number of adult males per adult female. The small number of adults per group (mean=3.2) may result from balancing feeding competition against predator detection. Augmenting the mate pool available from the group with mates from neighboring groups may promote the notable variability seen in the adult group compositions of sifakas.

Dynamic adjustment of parental care in response to perceived paternity.

Theories of parental care evolution predict that genetic relatedness will be an important variable in the amount of care a parent provides. However, current inferences of relatedness-based parental investment from studies in humans and birds remain challenged. No study has yet demonstrated parental care adjustment in a manner uncomplicated by life-history correlates or experimental design. We now present a unique test that controls for individual life histories and demonstrates paternity-related dynamic adjustments in parental care. Brood-rearing male bluegill sunfish (Lepomis macrochirus) that are cuckolded to a varying degree will either increase or decrease their parental investment in response to changing information on paternity during brood development. Specifically, as parental males detect paternity lost to cuckolders and, hence, a reduction in the value of their brood, they adaptively lower their level of parental care. Conversely, if they detect that their paternity is higher than previously assessed, they adaptively raise their level of parental care. This dynamic adjustment during brood rearing indicates the importance of genetic relatedness in parental investment decisions and provides needed empirical support for theoretical predictions.

Population structure and breeding system of the sex‐role reversed, polyandrous Bronze‐winged Jacana Metopidius indicus

Bronze-winged Jacanas Metopidius indicus studied from 1995 to 1997 at Vembanur lake in southern India had a consistent sex-ratio bias of about 1.9 males per female. Only half of males and females defended territories and thus could breed; the remaining birds were non-resident floaters. Floaters were lighter and younger than residents Bronze-winged Jacanas were sex-role reversed: females were 60.3% heavier and behaviourally dominant to males, which carried tout all the incubation and chick care. The ratio of potential reproductive rates was skewed to females by about 4:1, indicating that strongly reversed sexual selection probably operates in this species. Each year about 60% of resident females were monogamous and 40% were polyandrous with up to four males. Over 60% of resident males were in polyandrous groups. Heavier females had larger harems and produced more clutches per season. The peak breeding season was late July to early September. Over 90% of clutches were depredated before hatching. Nearly half of clutches of artificial eggs were attacked by rodents, the rest by birds. Mean ciutch mass was only 16.8% of female mass, giving this species one of the greatest capacities of any shorebird for laying multiple clutches. High predation rates and low energetic costs of parental care may have been important factors influencing the evolution of sex-role reversal and polyandry in jacanas.

Balancing sexual selection through opposing mate choice and male competition

Male–male competition and female mate choice act contemporaneously in the cockroach Nauphoeta cinerea and the social pheromone of males influences the outcome of both forms of sexual selection. We therefore examined the joint and separate effects of male–male competition and female mate choice to determine if the selective optima for the pheromone were the same or different. Dominant males in a newly established hierarchy mated more frequently, but not exclusively. Manipulations of the multi-component social pheromone produced by males of N. cinerea showed that both long- and close-range attraction of females by males were influenced by the quantity and composition of the pheromone. The most attractive composition, however, differed from that which was most likely to confer high status to males. Since the outcome of male–male competition can conflict with mating preferences exhibited by females, there is balancing sexual selection on the social pheromone of N. cinerea. Such balancing selection might act to maintain genetic variation in sexually selected traits. We suggest that the different forms of sexual selection conflict in N. cinerea because females prefer a blend different to that which is most effective in male–male competition in order to avoid mating with overly aggressive males.