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During ex situ conservation, the adaptability of giant pandas to environmental changes is greatly challenged. The issue of natural reproduction in captive giant pandas remains unresolved both domestically and internationally. It hypothesized that the restricted natural reproductive capacity may be linked to abnormal mating behavior expression due to physiological stress resulting from incompatible pairings in confined environments. To test this hypothesis, we utilized ultra-high performance liquid chromatographytandem quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) to analyse urine metabolites in captive adult giant pandas during their breeding period. Simultaneously, enzyme-linked immunosorbent assay was employed to measure the levels of cortisol and epinephrine in urine, providing insight into the psychological state of captive giant pandas during mate selection by examining all metabolites and related biochemical pathways. This comprehensive approach aims to fully elucidate the physiological mechanisms underlying the decline in natural reproductive capacity. The metabolomics findings indicate that the aberrant expression of natural mating behaviour in captive adult male and female giant pandas may be associated with dysfunction in amino acid metabolic pathways. The activation of these metabolic pathways is linked to psychological stress, such as the tryptophan metabolic pathway and GABAergic synapse pathway. The results of physiological indicators indicate a significant correlation between the expression of natural mating behaviour in captive adult pandas and the hormone urine cortisol, which is associated with physiological stress. These findings indicate that the atypical manifestation of natural mating behaviour in captive adult giant pandas may be associated with physiological stress induced by incompatible pairings within confined environments.

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Socially plastic behaviours are widespread among animals and can have a significant impact on fitness. Here we investigated whether the socially plastic responses of female Drosophila melanogaster can evolve in predictable ways following long term manipulation of adult sex ratio and adult nutrient availability. Previous reports show that female D. melanogaster respond plastically to their same-sex social environment, and lay significantly fewer eggs after mating when previously exposed to other females. In this study, we tested two hypotheses, using females drawn from lines with an evolutionary history of exposure to variation in adult sex ratio (male biased, female biased or equal sex ratio) and adult nutritional environment (high or low quality). The first was that a history of elevated competition in female-biased regimes would select for increased plastic fecundity responses in comparison to females from other lines. The second was that these responses would also be magnified under poor nutritional resource regimes. Neither hypothesis was supported. Instead, we found that plastic fecundity responses were retained in females from all lines, and did not differ significantly across any of them. The lack of differences does not appear to be due to insufficient selection, as we did observe significant evolutionary responses in virgin egg laying patterns according to sex ratio and nutritional regime. The lack of variation in the magnitude of predicted plasticity is consistent with the idea that the costs of maintaining plasticity are low, benefits high, and that plasticity itself can be relatively hard wired.

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Speciation is a fundamental evolutionary process but the genetic changes accompanying speciation are difficult to determine since true species do not produce viable and fertile offspring. Partially reproductively isolated incipient species are useful for assessing genetic changes that occur prior to speciation. Drosophila melanogaster from Zimbabwe, Africa are partially sexually isolated from other D. melanogaster populations whose males have poor mating success with Zimbabwe females. We used the North American D. melanogaster Genetic Reference Panel (DGRP) to show that there is significant genetic variation in mating success of DGRP males with Zimbabwe females, to map genetic variants and genes associated with variation in mating success and to determine whether mating success to Zimbabwe females is associated with other quantitative traits previously measured in the DGRP. Incipient sexual isolation is highly polygenic and associated with the common African inversion In(3R)K and the amount of the sex pheromone 5,9-heptacosadiene in DGRP females. We functionally validated the effect of eight candidate genes using RNA interference to provide testable hypotheses for future studies investigating the molecular genetic basis of incipient sexual isolation in D. melanogaster.

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Exaggerated sexual traits, such as ornaments and courtship displays, are crucial for mate acquisition in many species and are often subject to directional runaway selection. However, in the face of high predation risk, natural selection can result in a reduction of conspicuous precopulatory displays to avoid detection by potential predators. Sexual selection may then favour increased investment in inconspicuous postcopulatory traits. Here, we investigated the transgenerational effects of predation on precopulatory male courtship and postcopulatory sexual traits (testes size, sperm length) in a dung fly, Sepsis punctum (Sepsidae). Behavioural assays prior to selection document a marked decrease in male courtship displays in the presence of a predator, the Asian Ant Mantis (Odontomantis planiceps). However, after ten generations of experimental evolution, flies exhibited a marked increase in courtship, both in the absence and presence of a predator. Additionally, under sustained predation pressure, male and female body size decreased but male postcopulatory traits were not significantly affected. These results suggest that precopulatory courtship can be under strong sexual selection even in the face of predation pressure. Larger flies were more susceptible to predation, and there could be canalisation of postcopulatory traits that are crucial for fertilisation.

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Fossilized mating insects are irreplaceable material for comprehending the evolution of the mating behaviours and life-history traits in the deep-time record of insects as well as the potential sexual conflict. However, cases of mating pairs are particularly rare in fossil insects, especially aquatic or semi-aquatic species. Here, we report the first fossil record of a group of water striders in copulation (including three pairs and a single adult male) based on fossils from the mid-Cretaceous of northern Myanmar. The new taxon, Burmogerris gen. nov., likely represents one of the oldest cases of insects related to the marine environment, such as billabongs formed by the tides. It exhibits conspicuous dimorphism associated with sexual conflict: the male is equipped with a specialized protibial comb as a grasping apparatus, likely representing an adaptation to overcome female resistance during struggles. The paired Burmogerris show smaller males riding on the backs of the females, seemingly recording a scene of copulatory struggles between the sexes. Our discovery reveals a mating system dominated by males and sheds light on the potential sexual conflicts of Burmogerris in the Cretaceous. It indicates the mating behaviour remained stable over long-term geological time in these water-walking insects.

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BACKGROUND: Anopheles gambiae continues to be widespread and an important malaria vector species complex in Uganda. New approaches to malaria vector control are being explored including population suppression through swarm reductions and genetic modification involving gene drives. Designing and evaluating these new interventions require good understanding of the biology of the target vectors. Anopheles mosquito swarms have historically been hard to locate in Uganda and therefore have remained poorly characterized. In this study we sought to identify and characterize An. gambiae s.l mosquito swarms in three study sites of high An. gambiae s.l prevalence within Central Uganda. METHODS: Nine sampling visits were made to three villages over a 2-year period. Sampling targeted both wet and dry seasons and was done for 2 days per village during each trip, using sweep nets. All swarm data were analysed using the JMP 14 software (SAS Institute, Inc., Cary, NC, USA), parametrically or non-parametrically as appropriate. RESULTS: Most of the An. gambiae s.s. swarms sampled during this study were single-species swarms. However, some mixed An. gambiae s.s. and Culex spp. mosquito swarms were also observed. Swarms were larger in the wet season than in the dry season. Mean swarm height ranged from 2.16 m to 3.13 m off the ground and only varied between villages but not by season. Anopheles gambiae mosquitoes were present in all three villages, preferred to swarm over bare ground markers, and could be effectively sampled by field samplers. CONCLUSIONS: This study demonstrated that An. gambiae s.l swarms could be effectively located and sampled in South Central Uganda and provided in-depth descriptions of hitherto poorly understood aspects of An. gambiae local swarm characteristics. Swarms were found close to inhabited households and were greater in size and number during the rainy season. Anopheles gambiae s.s swarms were significantly associated with bare ground markers and were sometimes at heights over 4 m above the ground, showing a necessity to develop tools suitable for swarm sampling at these heights. While mixed species swarms have been reported before elsewhere, this is the first documented instance of mixed genus swarms found in Uganda and should be studied further as it could have implications for swarm sampling explorations where multiple species of mosquitoes exist.

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The exposure to sublethally high temperature reduces reproductive performance in diverse organisms. Although this effect has been particularly emphasized for males or male reproductive functioning, it remains largely unknown whether the effect of heat on fertility is sex-specific. Here we examined the impact of sublethally high temperature on male and female functions in a simultaneously hermaphroditic snail species, Lymnaea stagnalis. Examining hermaphrodites is useful to evaluate the sex-specific impacts of heat exposure, since they possess male and female functions within a single individual, sharing genetic and environmental factors. Moreover, previously developed sex allocation theory allows us to compare the differential performance of sex functions. In this study, we exposed snails to 20°C (control), 24°C and 28°C for 14 days and assessed their egg and sperm production, sperm transfer, mating behaviour and growth. Both types of gamete production were significantly reduced by higher temperature, leading to an overall reduction of reproductive investment. By quantifying sex allocation, we furthermore revealed that the heat-stressed snails reduced the relative investment in their male function. This study illustrates that examining simultaneous hermaphrodites can provide significant insights for the impact of heat, and the proximate mechanism, on reproduction in diverse organisms.

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Sexual selection and the evolution of costly mating strategies can negatively impact population viability and adaptive potential. While laboratory studies have documented outcomes stemming from these processes, recent observations suggest that the demographic impact of sexual selection is contingent on the environment and therefore may have been overestimated in simple laboratory settings. Here we find support for this claim. We exposed copies of beetle populations, previously evolved with or without sexual selection, to a 10-generation heatwave while maintaining half of them in a simple environment and the other half in a complex environment. Populations with an evolutionary history of sexual selection maintained larger sizes and more stable growth rates in complex (relative to simple) environments, an effect not seen in populations evolved without sexual selection. These results have implications for evolutionary forecasting and suggest that the negative demographic impact of sexually selected mating strategies might be low in natural populations.

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Human-induced climate change is leading to higher average global temperatures and increasingly extreme weather events. High temperatures can have obvious effects on animal survival, particularly in ectotherms. However, the temperature at which organisms become sterile may be significantly lower than the temperature at which other biological functions are impaired. In the fruit fly Drosophila virilis, males are sterilized at temperatures above 34 °C, but are still active and able to mate normally. We investigated the male behavioural changes associated with high-temperature fertility loss. We exposed males to a warming treatment of 34.4 °C or 36.6 °C for 4 h, and then recorded their mating behaviour after being allowed to recover for 24 h. Previous work in this species suggests that males exposed to 34.4 °C lose the ability to produce new sperm, but can utilize mature sperm produced before the heat shock. We therefore predicted that these males would increases their courtship rate, and reduce their choosiness, in order to try to ensure a mating before their remaining mature sperm die. In contrast, over two-thirds of males exposed to 36.6 °C are completely sterile. In standard mating trials, earlier exposure to 34.4 °C or 36.6 °C did not affect male courtship behaviour when compared to control males kept at 23 °C. Exposure to high temperatures also did not alter the extent to which males directed courtship toward females of the same species. However, males exposed to 36.6 °C were significantly slower to mate, and had a reduced likelihood of mating, when compared to control males. Overall, exposure to high temperatures did not alter male courtship behaviour, but did lower their likelihood of mating. This suggests that females can distinguish between normal and heat-sterilized males before mating, and that female mate choice may at least partly mitigate the population-level consequences of high-temperature induced male sterility in this species.

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Osmia cornuta Latr. is largely managed worldwide for the pollination of orchard crops, playing a key role in the maintenance of healthy ecosystems and ensuring economic and social benefits for human society. The management techniques of this pollinator include the possibility of delaying emergence from cocoons after diapause, allowing for the pollination of later-blooming fruit crops. In this study, the mating behaviour of bees emerging at the natural time (Right Emergence Insects) and of late-emerged bees (Aged Emergence Insects) was described in order to test if a delay in emergence could affect the mating sequence of O. cornuta. Markov analysis of the mating behaviour revealed the occurrence of antenna motion episodes that were repeated in a stereotyped manner at regular intervals during the mating sequence of both Right Emergence Insects and in Aged Emergence Insects. Pouncing, rhythmic and continuous emission of sound, motion of antennae, stretching of the abdomen, short and long copulations, scratching, inactivity, and self-grooming were identified as the stereotyped behavioural units of a behavioural sequence. The occurrence of short copulations, the frequency of which increased with the age of bees, could lead to a failure in the reproduction of the mason bee.

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In Caenorhabditis elegans, a species reproducing mostly via self-fertilization, numerous signatures of selfing syndrome are observed, including differences in reproductive behaviour compared to related obligatory outcrossing species. In this study we investigated the effect of nearly 100 generations of obligatory outcrossing on several characteristics of male reproductive behaviour. A genetically uniform ancestral population carrying a mutation changing the reproductive system to obligatory outcrossing was split into four independent populations. We predicted that the transition from the natural reproductive system, where males were extremely rare, to obligatory outcrossing, where males comprise 50% of the population and are necessary for reproduction, will increase the selection pressure on higher effectiveness of mating behaviour. Several characteristics of male mating behaviour during a 15 min interaction as well as copulation success were compared between the ancestral and evolved populations. No significant differences in male mating behaviour or fertilization success were detected between generations 1 and 97 of obligatory outcrossing populations. We found, however, that longer contact with females increased chances of successful copulation, although this effect did not differ between populations. We conclude that either selection acting on male mating behaviour has not been strong enough, or mutational input of new adaptive variants has not been sufficient to cause noticeable behavioural differences after 97 generations of evolution starting from genetically uniform population.

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Mating rate optima often differ between the sexes: males may increase their fitness by multiple mating, but for females multiple mating confers little benefit and can often be costly (especially in taxa without nuptial gifts or mala parental care). Sexually antagonistic evolution is thus expected in traits related to mating rates under sexual selection. This prediction has been tested by multiple studies that applied experimental evolution technique, which is a powerful tool to directly examine the evolutionary consequences of selection. Yet, the results so far only partly support the prediction. Here, we provide another example of experimental evolution of sexual selection, by applying it for the first time to the mating behaviour of a seed beetle Callsorobruchus chinensis. We found a lower remating rate in polygamy-line females than in monogamy-line (i.e. no sexual selection) females after 21 generations of selection. Polygamy-line females also showed a longer duration of first mating than monogamy-line females. We found no effect of male evolutionary lines on the remating rate or first mating duration. Though not consistent with the original prediction, the current and previous studies collectively suggest that the observed female-limited responses may be a norm, which is also consistent with the conceptual advances in the last two decades of the advantages and limitations of experimental evolution technique.

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Animals adapt to their environments in the course of evolution. One effective approach to elucidate mechanisms of adaptive evolution is to compare closely related species with model organisms in which knowledge of the molecular and physiological bases of various traits has been accumulated. Drosophila elegans and its close relatives, belonging to the same species group as the model organism D. melanogaster, exhibit various unique characteristics such as flower-breeding habit, courtship display, territoriality, sexual dimorphism, and colour polymorphism. Their ease of culturing and availability of genomic information makes them a useful model for understanding mechanisms of adaptive evolution. Here, we review the morphology, distribution, and phylogenetic relationships of D. elegans and related species, as well as their characteristic flower-dependent biology, food habits, and life-history traits. We also describe their unique mating and territorial behaviours and note their distinctive karyotype and the genetic mechanisms of morphological diversity that have recently been revealed.

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Detailed animal movement analysis can help understand spatial population processes as the ultimate consequences of individual behaviour and ecological impacts. The mating strategy of mammalian herbivores is adapted to the distribution of females; thus, it is important to observe the activity of animals during a rut. In this paper, we used a new approach to examine the relationship between red deer stags' movement activity and the fertile period of hinds. We presumed a relationship between stags' daily activity changes and the period when hinds are in heat. We determined temporal conception trends, including the first and last conception dates in the examined population and the conception peak. In the same period, i.e., in the interval of major ecological significance when mating takes place, the activity of stags was analysed by GPS telemetry. The data collected in the examined period indicate that 60% of the hinds were conceived between 31 August and 19 September. We demonstrated that conception rates differed significantly between the first and second half of the rutting period. At the beginning of the reproductive cycle, the high number of hinds on heat (oestrus synchrony) increased the activity of stags (harem herding) compared to the pre-rutting period. As the mating season progressed, the movement activity of stags increased more (searching behaviour), induced by the decreasing number of fertile hinds. Therefore, we found that the oestrus of hinds significantly influenced the movement activity of stags in red deer.

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Doublesex (Dsx) has a conserved function in controlling sexual morphological differences in insects, but our knowledge of its role in regulating sexual behaviour is primarily limited to Drosophila. Here, we show with the parasitoid wasp Nasonia vitripennis that males whose Dsx gene had been silenced (NvDsx-i) underwent a three-level pheromonal feminization: (i) NvDsx-i males were no longer able to attract females from a distance, owing to drastically reduced titres of the long-range sex pheromone; (ii) NvDsx-i males were courted by wild-type males as though they were females, which correlated with a lower abundance of alkenes in their cuticular hydrocarbon (CHC) profiles. Supplementation with realistic amounts of synthetic (Z)-9-hentriacontene (Z9C31), the most significantly reduced alkene in NvDsx-i males, to NvDsx-i males interrupted courtship by wild-type conspecific males. Supplementation of female CHC profiles with Z9C31 reduced courtship and mating attempts by wild-type males. These results prove that Z9C31 is crucial for sex discrimination in N. vitripennis; and (iii) Nvdsx-i males were hampered in eliciting female receptivity and thus experienced severely reduced mating success, suggesting that they are unable to produce the to-date unidentified oral aphrodisiac pheromone reported in N. vitripennis males. We conclude that Dsx is a multi-level key regulator of pheromone-mediated sexual communication in N. vitripennis.

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The Aphelinus asychis female adult is an important arrhenotocous parthenogenesis parasitoid of Myzus persicae, and its reproductive mode is beneficial for the population continuation of A. asychis by way of multiple mating and backcross. To explore the effect of mating on the population fitness and control efficiency of A. asychis, its mating frequency and backcross were observed under laboratory conditions. The results showed that most matings in A. asychis involved four distinct stages: courtship, pre-copulatory, copulation, and post-copulatory behaviours. Only the duration of courtship increased significantly with an increase in copulation frequency for females, and the courtship duration of A. asychis females mated with different males were significantly shorter than those mated with the same male at the same mating times, which suggested that A. asychis females might prefer to mate with different males to enrich the genotype of their offspring. The total number of mummified aphids and the female and male longevity decreased significantly with an increase in mating frequency. On the contrary, female progenies increased significantly with an increase of mating frequency, suggesting that sperm limitation might occur in females when they only mated once. These results imply that females might prefer to receive more sperm by mating multiple times in their life span. In addition, we found that the intrinsic rate of increase (r) of A. asychis of the control group (0.2858 d-1) was significantly greater than that in the backcross treatment (0.2687 d-1). The finite killing rate (θ) of A. asychis of the control group was similar to that in the backcross treatment, which showed that this treatment had a negligible negative effect on the control efficiency of A. asychis. In conclusion, the results showed that multiple mating increased the number and proportion of A. asychis female progenies but shortened the longevity of female and male adults, while the negative effect of backcross on the control efficiency of A. asychis was negligible.

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This paper represents an attempt to investigate the mating behaviour of Symmorphus allobrogus, explaining the willingness of male to mount and copulate. The male displays including mode and frequency of antennation and position while copulating, the displays further comprises of intensity and frequency of rejecting behaviour. The presence of the male's copulatory and postcopulatory courtship studies, understands the maintenance of monandry. The wasp has numerous secondary sexual characters, and the mating behaviour follows a phyletic and the specific sexual mating characters in context of sexual selection. The duration of mating phases and the number of male antennation series during precopulatory, copulatory and postcopulatory phases of mounting, differs significantly. Mating success depends mostly on the activities of male in the premounting phase and the behaviour of both sexes has a roughly equal importance for it in precopulatory phase. While during copulation, activity of male has little influence on its duration; however, behaviour of female has crucial effect, inducing its earlier termination.

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INTRODUCTION: Male genitalia are thought to ensure transfer of sperm through direct physical contact with female during copulation. However, little attention has been given to their pre-copulatory role with respect to sexual selection and sexual conflict. Males of the fruitfly Drosophila pachea have a pair of asymmetric external genital lobes, which are primary sexual structures and stabilize the copulatory complex of female and male genitalia. We wondered if genital lobes in D. pachea may have a role before or at the onset of copulation, before genitalia contacts are made. RESULTS: We tested this hypothesis with a D. pachea stock where males have variable lobe lengths. In 92 mate competition trials with a single female and two males, females preferentially engaged into a first copulation with males that had a longer left lobe and that displayed increased courtship vigor. In 53 additional trials with both males having partially amputated left lobes of different lengths, we observed a weaker and non-significant effect of left lobe length on copulation success. Courtship durations significantly increased with female age and when two males courted the female simultaneously, compared to trials with only one courting male. In addition, lobe length did not affect sperm transfer once copulation was established. CONCLUSION: Left lobe length affects the chance of a male to engage into copulation. The morphology of this primary sexual trait may affect reproductive success by mediating courtship signals or by facilitating the establishment of genital contacts at the onset of copulation.

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Many forms of polygyny are observed across different animal groups. In some species, groups of females may remain with a single male for breeding, often referred to as "harem polygyny". The environment and the amount of habitat available for feeding, mating and oviposition may have an effect on the formation of harems. We aimed to determine how the surrounding environment (a harvested or unharvested pine plantation) and availability of local substrate affect the harems of the bark beetle, Ips grandicollis (Coleoptera: Curculionidae: Scolytinae). In a harvested pine plantation with large amounts of available habitat, the population density of these beetles is much higher than in unharvested plantations. We found the number of females per male to be significantly greater in the harvested plantation than the unharvested one. Additionally, the amount of substrate available in the immediate local vicinity (the number of logs in replicate piles) also influences the number of beetles attracted to a log and size of individual harems. We also examined how females were distributing themselves in their galleries around the males' nuptial chamber, as previous work has demonstrated the potential for competition between neighbouring females and their offspring. Females do not perform clumping, suggesting some avoidance when females make their galleries, but they also do not distribute themselves evenly. Female distribution around the male's nuptial chamber appears to be random, and not influenced by other females or external conditions.

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BACKGROUND: The sterile insect technique (SIT) is used in Australia to contain and eradicate outbreaks of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) in fruit-fly-free regions, and to manage populations in some endemic regions. To assess the likely impact of SIT on wild B. tryoni populations it is important to assess the colocation and synchrony of male calling between sterile and wild flies. We observed the location and timing of calling behaviours of marked mass-reared (fertile and sterile) and wild B. tryoni males in walk-in field cages. RESULTS: We found that wild males called further from the canopy centre than mass-reared (fertile or sterile) males. Mass-reared (fertile or sterile) males called earlier in the evening than wild males and, consequently, mass-reared males called when temperature and light intensity were higher than when wild males called. CONCLUSION: Male calling is a prerequisite to mating among dacine fruit flies. Therefore, our observations of spatio-temporal divergence in male calling behaviour may lead to assortative mating between mass-reared and wild B. tryoni in SIT applications. The importance of these spatio-temporal differences warrants further inquiry, with particular focus on how environmental conditions modify calling behaviour and avenues to ameliorate differences between sterile and wild flies. © 2021 Society of Chemical Industry.

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