Successful Copulation Research Articles

Older males are more competitive in male fights and more aggressive toward females in the broad-horned flour beetle Gnatocerus cornutus

In theory, a male should change the allocation of fighting and mating efforts in relation to his age. Thus, the consequences of sexual selection may be complicated by changes in the male resource allocation due to aging. However, previous studies have focused on changes in female mate choice and male-male competition with aging separately, and the impact of aging on the relationship between mate choice and male competition is unknown. Here, we examined how male competitiveness and attractiveness and their relationship changes over male lifespan in Gnatocerus cornutus. In this species, males perform courtship displays and fight rival males for mates. Older males are more competitive in male fighting and aggressive toward females than younger males. The aggression is also directed toward females. Almost all older males who attacked a female failed to copulate, while younger males never attacked the females. As a result, copulation success decreased with age. When an older male did not mistake a female for a male, he exhibited more frequent courtship. However, mating with older males imposed direct costs on females in terms of both fecundity and lifespan, with no offsetting indirect benefits for her offspring. The courtship behavior of older males does not supply females with cues for mate-choice benefits but are used to coerce females into mating. Our results suggest that male–male competition constrains female preference for older males. Thus, female choice and male–male competition may not be reinforcing in older G. cornutus males. When males get older, they often pay more attention to females in a variety of ways, such as courting and fighting for access. This is because older males have not long to live. In Gnatocerus cornutus as well, older males attend to fighting and courting. The older males seem to be competitive in male fights and attractive to females. However, they are not only aggressive toward rival males but also sometimes use violence on females. As a result, these older males are rejected by the assaulted females and cannot mate. Additionally, the violence of older males can reduce female fecundity and lifespan. Thus, mating with older males is costly to females in G. cornutus, and a female preference for older males is not expected to evolve.

Strong sexual selection despite spatial constraints on extrapair paternity

Abstract Extrapair paternity should contribute to sexual selection by increasing the number of potential mates available to each individual. Potential copulation partners are, however, limited by their proximity. Spatial constraints may therefore reduce the impact of extrapair paternity on sexual selection. We tested the effect of spatial constraints on sexual selection by simulating extrapair copulations for 15 species of socially monogamous songbirds with varying rates of extrapair paternity. We compared four metrics of sexual selection between simulated populations without spatial constraints and populations where extrapair copulations were restricted to first- and second-order neighbors. Counter to predictions, sexual selection as measured by the Bateman gradient (the association between the number of copulation partners and offspring produced) increased under spatial constraints. In these conditions, repeated extrapair copulations between the same individuals led to more offspring per copulation partner. In contrast, spatial constraints did somewhat reduce sexual selection—as measured by the opportunity for selection, s’max, and the selection gradient on male quality—when the association between simulated male quality scores and copulation success (e.g., female preferences or male–male competition) was strong. Sexual selection remained strong overall in those populations even under spatial constraints. Spatial constraints did not substantially reduce sexual selection when the association between male quality and copulation success was moderate or weak. Thus, spatial constraints on extrapair copulations are insufficient to explain the absence of strong selection on male traits in many species.

Variation in Lek Attendance and Copulation Success of Independent and Satellite Male Ruffs Calidris pugnax

In lekking male Ruffs, three genetically distinct morphs compete for copulations with the visiting females. Faeder males are female mimics, whereas Independents and Satellites show marked sexual dimorphism, including an elaborate ornamental plumage. Independent males holding a territory on a lek (Residents) have higher mating success than Independents that do not (Marginals), whereas heterogeneity among Satellites is less well understood. Therefore, we compare variation in lek attendance and copulation success between Independent and Satellite males on five leks in northern Norway, over one mating season. Among Independents, Residents were more likely to return to the same lek between years, had longer tenure, higher visitation rate, longer visit duration, fewer arrivals and departures from the lek together with females, and higher daily and seasonal lek attendance than Marginals. We observed qualitatively similar between-individual variation in behaviour among Satellites. Thus, we define two types of individuals: Central Satellites with high lek attachment and Peripheral Satellites with low lek attachment. A notable difference between the morphs was that some Central Satellites (but no Resident Independents) were highly attached to more than one lek on the same day. Lek attendance correlated with copulation success, both on a daily basis and considering the entire season, and this relationship did not differ significantly between the morphs. Given that the mere presence of a male on the lek when a female visited to copulate predicted his copulation success, the unequal distribution of copulations on a lek can be largely explained by unequal lek attendance. After correction for variation in presence, one male on each lek obtained more than his expected share of copulations. Our observations suggest that endurance rivalry, whereby energetic limitations determine the lek attendance of competing males, could be an important determinant of copulation success on Ruff leks.

Characterization of the estrous cycle in the Amazon spiny rat (Proechimys guyannensis)

Males of Proechimys guyannensis, a rodent living in the Amazon rainforest are studied in biomedical research because of their antiepileptogenic mechanism. Females are usually taken from experimental designs, because of limited data of this sex. This study aimed to characterize the estrous cycle to include females together with males in research in a more balanced approach. The estrous cycle of P. guyannensis based through exfoliative cytology, determination of the vaginal occlusion membrane state, and hormonal analysis. In this study, cytological analyses of vaginal smears were performed for three months, three times a day. The observed length of the estrous cycle was 247 ± 81 h (mean ± SD) with a reproductive phase of 27.08 ± 17.39 h (estrus stage). We observed a frequent presence of both the open and closed states of the vaginal membrane in the estrus stage (fertile period) although only the open stage is a prerequisite for successful copulation. High levels of progesterone and estradiol were detected in proestrus. Levels of follicle-stimulating hormone peaked at the estrus stage. These data will establish the parameters and subsidies to set the grounds for future research either for investigating the biology of this species or to use P. guyannensis in research that previously excluded females. Information regarding female Proechimys is relevant to not only describe the species but also explain the interaction between sex hormones and physiological responses. Moreover, the present results will enhance rigor and reproducibility in preclinical studies. In conclusion, P. guyannensis reproductive cycles can occur spontaneously and cyclically independent of mating stimulation and the high levels of FSH in the estrus stage, suggest that ovulation occurs in the late phase of the estrus.

A mismatch between signal transmission efficacy and mating success calls into question the function of complex signals

Variation in transmission characteristics of signalling environments is hypothesized to influence the evolution of signalling behaviour, signal form and sensory systems of animals. However, many animals communicate across multiple signalling environments, raising the possibility that some displays have evolved explicitly to enable communication across heterogeneous signalling environments. In the present paper, we explored multiple potential impacts of the signalling environment on courtship displays in the wolf spider Schizocosa retrorsa. Males of this species court females on a range of substrate types using a combination of vibratory and visual signals. Through a series of experiments, we investigated (1) activity patterns and male microhabitat use, (2) component-specific vibratory signal transmission across natural substrate types and (3) copulation success across substrate types and light levels. We found that, in the laboratory, (1) female and male S. retrorsa are most active during daylight hours, and mature males resided and courted most on leaf litter, as compared to their natural habitat types of pine litter or sand; (2) male vibratory courtship signals transmitted best on leaf litter, yet (3) males obtained the highest copulation success on sand, regardless of light level. Our results demonstrate that copulation in S. retrorsa is more likely to occur in environments with suboptimal vibratory signal transmission, irrespective of visual signal transmission. We suggest that these results point to (1) a minor role of bimodal (vibratory and visual) courtship signalling in S. retrorsa, (2) the importance of an additional signalling modality (most likely air particle movement), (3) a role of other substrate-dependent factors (e.g. predation risk), and/or (4) a reversed female preference for vibratory signalling.

Genetic variation in sexual aggression and the factors that determine forced copulation success

Sexual conflict is common in nature and sometimes results in sexual aggression. An extreme case is forced copulation, where one individual forcibly mates with another individual who resists the mating. To understand what makes some males sexually aggressive, we established an experimental system that allowed us to quantify the characteristics that contribute to males' forced copulation success. In fruit flies (Drosophila melanogaster), sexually mature females can choose to accept or reject courting males; however, males can forcibly copulate with newly eclosed, sexually immature, teneral females. We tested males from 59 genotypes and found significant genetic variation in forced copulation success, with a broad-sense heritability of 0.16. We then chose three genotypes with the lowest and three genotypes with the highest forced copulation success rates and compared the behaviour of males from these two groups. Males from genotypes with high forced copulation success were more persistent in their pursuit of teneral females and mounted them more frequently than did males from the low-success genotypes. Males of the two categories, however, were similar in their attractiveness to both teneral and sexually mature females. Our results suggest that males vary in their pursuit strategies. Some males respond to female rejection signals by giving up and searching for receptive females, while other males persist in pursuit and coercion in spite of female objection. Our work highlights the practicality of using forced copulation in fruit flies as a model for further research on the mechanisms affecting variation in sexual coercion and forced copulation success and their evolutionary consequences.

Sperm allocation strategies in a sperm heteromorphic insect.

Theories predict that in polyandrous species, the focal male should increase sperm allocation per mate in the presence of rivals to gain greater share of paternity, but in the presence of additional mates, he should reduce sperm allocation per mate to save sperm for insemination of more mates. However, empirical findings are often inconsistent and reasons behind are unclear. Furthermore, many studies use copulation duration as an estimate of the number of sperm transferred. Yet, empirical evidence for such assumption is largely lacking. Here, we used a sperm heteromorphic insect Ephestia kuehniella whose males produce two types of sperm, eupyrenes (fertile) and apyrenes (nonfertile), to test these postulations. We allowed focal males to detect chemical and acoustic but no tactile cues from rivals or additional mates both before and during mating and measured copulation duration and sperm allocation in successive copulations. We demonstrate that males transfer significantly more eupyrenes per mate in the presence of rivals and that the sperm allocation pattern persists in successive copulations under this condition. However, males do not adjust apyrene allocation in response to rivals probably because apyrenes play a relatively minor role in male reproductive success. Contrary to a previous study, focal males do not respond to additional mates most likely due to the lack of tactile cues in the present study. We reveal that sperm allocation is not a function of copulation duration in this insect for spermatophore formation and delivery occupy most of copulation duration and sperm transfer is complete near the end of copulation.

Precopulatory acoustic interactions of the New World malaria vector Anopheles albimanus (Diptera: Culicidae)

BackgroundAnopheles albimanus is a malaria vector in Central America, northern South America and the Caribbean. Although a public health threat, An. albimanus precopulatory mating behaviors are unknown. Acoustics play important roles in mosquito communication, where flight tones allow males to detect and attract potential mates. The importance of sound in precopulatory interactions has been demonstrated in Toxorhynchites brevipalpis, Aedes aegypti, Culex quinquefasciatus and Anopheles gambiae; convergence in a shared harmonic of the wing beat frequency (WBF) during courtship is thought to increase the chance of copulation. To our knowledge, An. albimanus precopulatory acoustic behaviors have not been described to date. Here, we characterized An. albimanus (i) male and female flight tones; (ii) male–female precopulatory acoustic interactions under tethered and free flight conditions; and (iii) male-male acoustic interactions during free flight.ResultsWe found significant increases in the WBFs of both sexes in free flight compared to when tethered. We observed harmonic convergence between 79% of tethered couples. In free flight, we identified a female-specific behavior that predicts mate rejection during male mating attempts: females increase their WBFs significantly faster during mate rejection compared to a successful copulation. This behavior consistently occurred during mate rejection regardless of prior mating attempts (from the same or differing male). During group flight, males of An. albimanus displayed two distinct flying behaviors: random flight and a swarm-like, patterned flight, each associated with distinct acoustic characteristics. In the transition from random to patterned flight, males converged their WBFs and significantly decreased flight area, male-male proximity and the periodicity of their trajectories.ConclusionsWe show that tethering of An. albimanus results in major acoustic differences compared to free flight. We identify a female-specific behavior that predicts mate rejection during male mating attempts in this species and show that male groups in free flight display distinct flying patterns with unique audio and visual characteristics. This study shows that An. albimanus display acoustic features identified in other mosquito species, further suggesting that acoustic interactions provide worthwhile targets for mosquito intervention strategies. Our results provide compelling evidence for swarming in this species and suggests that acoustic signaling is important for this behavior.

Sexually opposite effects of testosterone on mating success in wild rock hyrax

Abstract Although males and females share traits, their motivations and needs may be different, due to life-history disparities that lead to divergent selection pressures. Proximate mechanisms underlying differences between the sexes include hormones that mediate the development and activation of suites of traits. Testosterone is associated with morphological features, physiological processes, and social behaviors in both sexes. However, even if present in similar concentrations in the circulation, testosterone often affects males and females differently. We combined behavioral mating observations of the wild polygynandrous rock hyrax (Procavia capensis) with hair testosterone that represents long-term integrated levels. We found that whereas copulation success increases with the rise in testosterone in males it decreases in females. We did not find an association between testosterone and choosiness in either sex. However, we found that males with higher testosterone mate-guarded females with lower testosterone. Our findings show disassortative mating and mate-guarding in respect to testosterone and provide clues to the cost of testosterone for females, in terms of copulation success. These results open up intriguing questions relating to the role of testosterone in mediating a similar trade-off in male and female reproductive success.

Mating experience affects male mating success, but not female fecundity in the wolf spider Pardosa pseudoannulata (Araneae: Lycosidae)

In a mating system in which females are monandrous and males are polygynous, females may incur a risk by mating with males with possible sperm depletion following consecutive matings. Here, we examined the effects of male mating history on male mating success and female reproductive fitness in the wolf spider Pardosa pseudoannulata by performing mating trials and sperm counting experiments. Results showed that male mating history had a significant negative impact on subsequent copulation success but had little effect on courtship duration and courtship intensity. In addition, neither male courtship intensity nor morphological measurements of males and females had significant effects on male mating success. Furthermore, male mating history had no obvious impact on the fecundity of inseminated females, with no significant differences observed in the oviposition rate of females, the numbers and the carapace width of the second-instar spiderlings between treatments. Results showed that the number of sperm decreased significantly after mating but could be replenished, with no significant differences observed between groups in which males had rested for 7 d. These findings suggest that polygynous male spiders may recharge their sperm during the mating season, but how females differentiate the mating status of males remains unknown.

Cuticular Hydrocarbon Recognition in the Mating Behavior of Two Pissodes Species.

Two sibling weevil species, Pissodes strobi Peck and P. nemorensis Germar (Coleoptera: Curculionidae), can form reduced-fitness hybrids in the laboratory, but neither their premating isolation mechanisms nor mating behaviors are well-understood. Cuticular hydrocarbons (CHCs) have been reported as crucial chemical cues in mating recognition in many insects, including weevils, and, thus, may also mediate the mating behavior of P. strobi and P. nemorensis. We conducted a series of behavioral observations, bioassays, and chemical analyses to investigate the role of CHCs in their mating behavior. Copulation behavior of both species followed similar steps: approaching, mounting, tapping, aedeagus extrusion, and copulation. In P. strobi, hexane extraction significantly reduced the number of successful male copulations compared with freeze-killed females. Conversely, significantly fewer P. nemorensis males copulated with dead females compared with live females. No significant differences were detected among hexane-extracted, freeze-killed or recoated female carcasses to P. nemorensis. These findings suggested that female cuticular extracts contain important cues in mate recognition in P. strobi but not in P. nemorensis. We identified 21 CHCs from both species with variation in abundances between sexes and seasons. Discriminant analysis revealed incomplete overlap of CHC compositions in females of the two species in summer, when hybridization potentially occurs.

Behavioral Responses and Pupa Development Patterns After Hypoxia or Anoxia in a Desiccation-Resistant Anastrepha ludens Strain.

The aim of this study was to experimentally test for adult cross-resistance to hypoxia or anoxia in a desiccation-resistant population of Anastrepha ludens Loew. We compared desiccation resistant flies with unselected (control) flies by measuring the effect of pre-emergence hypoxia on some fitness parameters (emergence, flight ability, copulation success, latency to copulation, copulation duration, ovary size). Anoxia effects were determined using eye color changes during pupa development and fly emergence after re-oxygenation. Both strains were negatively affected in all measured parameters when exposed to hypoxia for more than 48h. However, after hypoxia, control flies showed, in general, shorter latency to mate and longer copula duration than desiccation-resistant flies. Anoxia-induced arrest of pupa development, whereas returning to normoxia conditions induced resumption of development. Anoxia period length (longer than 72h) increased mortality to 100% in the control line, whereas the desiccation-resistant line survived even at 120h of anoxia. Thus, pre-release hypoxia must not exceed 24h in order to maintain insect quality independently of fly type.

Let's mate here and now – seasonal constraints increase mating efficiency

1. Latitudinal climatic conditions shape the length of the mating season and could thus influence reproductive traits. Knowledge of how animals behave along latitudinal clines will increase understanding of the impact of climate on sexual selection and might help in the prediction of whether peripheral populations will spread or shrink in response to changes in climate.2. This study investigated variation in the mating efficiency of a temperate insect, the emerald damselfly Lestes sponsa, under semi‐natural field conditions along a latitudinal gradient covering three regions of the species' distribution: south, central and north.3. A comparison was done of the proportion of copulating males, the proportion of males that formed tandems but did not copulate (unsuccessful males), and the proportion of males that did not attempt to form a tandem (passive males) in these three regions.4. It was found that the proportion of copulations was significantly higher at northern latitudes than in the southern and central regions. Southern latitudes had a higher proportion of successful copulations compared with central latitudes. The northern region had a significantly lower frequency of passive males. The southern region had an intermediate proportion of passive males, and the central region had the highest proportion. The proportion of unsuccessful males did not differ between regions. The population density across sites did not affect these results.5. The study shows that damselflies inhabiting northern populations mate more intensively than individuals from southern and central populations. This suggests that more restrictive environmental conditions during a brief mating season select for higher mating efficiency.

Activity-dependent visualization and control of neural circuits for courtship behavior in the fly Drosophila melanogaster

Males of Drosophila melanogaster exhibit stereotypic courtship behavior through which they assess potential mates by processing multimodal sensory information. Although previous studies revealed important neural circuits involved in this process, the full picture of circuits that participate in male courtship remains elusive. Here, we established a genetic tool to visualize or optogenetically reactivate neural circuits activated upon specific behavior, exploiting promoter activity of a neural activity-induced gene Hr38 With this approach, we visualized neural circuits activated in the male brain and the ventral nerve cord when a male interacted with a female. The labeling of neural circuits was additively dependent on inputs from antennae and foreleg tarsi. In addition, neural circuits that express the sex-determining gene fruitless or doublesex were extensively labeled by interaction with a female. Furthermore, optogenetic reactivation of the labeled neural circuits induced courtship posture. With this mapping system, we found that a fruitless-positive neural cluster aSP2 was labeled when a male interacted with a female, in addition to previously characterized neurons. Silencing of neurons including aSP2 led to frequent interruption of courtship and significant reduction of mating success rate without affecting latency to start courtship, suggesting that these neurons are required for courtship persistency important for successful copulation. Overall, these results demonstrate that activity-dependent labeling can be used as a powerful tool not only in vertebrates, but also in invertebrates, to identify neural circuits regulating innate behavior.

Proper direction of male genitalia is prerequisite for copulation in Drosophila, implying cooperative evolution between genitalia rotation and mating behavior

Animal morphology and behavior often appear to evolve cooperatively. However, it is difficult to assess how strictly these two traits depend on each other. The genitalia morphologies and courtship behaviors in insects, which vary widely, may be a good model for addressing this issue. In Diptera, phylogenetic analyses of mating positions suggested that the male-above position evolved from an end-to-end one. However, with this change in mating position, the dorsoventral direction of the male genitalia became upside down with respect to that of the female genitalia. It was proposed that to compensate for this incompatibility, the male genitalia rotated an additional 180° during evolution, implying evolutionary cooperativity between the mating position and genitalia direction. According to this scenario, the proper direction of male genitalia is critical for successful mating. Here, we tested this hypothesis using a Drosophila Myosin31DF (Myo31DF) mutant, in which the rotation of the male genitalia terminates prematurely, resulting in various deviations in genitalia direction. We found that the proper dorsoventral direction of the male genitalia was a prerequisite for successful copulation, but it did not affect the other courtship behaviors. Therefore, our results suggested that the male genitalia rotation and mating position evolved cooperatively in Drosophila.

Anogenital distance predicts sexual odour preference in African giant pouched rats

Identifying reproductively viable partners may be the most important aspect of searching for a mate. When females vary in their reproductive receptivity, it is incumbent upon males to discriminate among females based on the likelihood of successful copulation and fertilization. We have observed that female African giant pouched rats (Cricetomys ansorgei) demonstrate profoundly delayed sexual development, with some adults exhibiting a highly neotenous, fully fused vagina. To say that the lack of vaginal patency presents a barrier to mating is a tremendous understatement. Based on this unique observation, we tested male preferences towards urine collected from patent and nonpatent females. We found that males with longer anogenital distances (AGD; a proximate measure of developmental masculinization) show differential interest towards patent and nonpatent females, preferring patent females. Strikingly, males with short AGDs did not show any differential interest between female odours. Correspondingly, only patent females demonstrated reduced interest in odour from short AGD males; nonpatent females did not demonstrate a preference. Our study demonstrates that pouched rats show differential interest in odours closely associated with mate quality. We are the first, to our knowledge, to show that the AGD of the evaluator enhances mate preferences and influences their interest in potential mating partners.

Vocalization can mediate male–male sexual interactions in Java sparrows

Abstract Same-sex sexual behaviors do not have direct fitness outcomes, but might be adaptive. This issue is often discussed in group-living animals, where social bonding is crucial. In our captive environment, around 33% of the Java-sparrow (Lonchura oryzivora) males kept in unisex cages have stable bonded partners. Those bonded males often perch side by side and show allopreening and joint-defensive behaviors towards others. In this study, we aimed to determine how males including such same-sex bonded individuals communicate with each other via vocalizations. We introduced same-sex pairs of Java sparrows, which were bonded or non-bonded, in sound-attenuated boxes and compared their recorded vocalizations with those from male–female pairs. For the male–male pairs, we identified two vocalizations that are usually exchanged between paired partners in intimate contexts: mating trills – which are usually emitted by females during successful copulation – and meowing calls – which are given when both members of the pair are in the nest at the same time. We found that males gave mating trills when their partner males were singing courtship songs, or performed trill duets, which sometimes also included meowing calls. Acoustic analyses revealed that there was no difference between male–male and male–female vocalizations. Meowing calls showed greater within-individual variation in duration and other acoustic parameters, but were similar in same-sex and mixed-sex contexts. Our results indicate that male–male pairs exchanged intimate vocal communications just like male–female couples.

Evaluation of management in North American zoos to enhance breeding success of the fishing cat (Prionailurus viverrinus) ex situ population.

The ex situ population of fishing cats (Prionailurus viverrinus) face many challenges to its sustainability such as mate incompatibility, low founder numbers and disease prevalence. The North American population was monitored for a three-year period during institutional transfers and breeding introductions. In total, 26 fishing cats, including 15 different breeding pairs were monitored during 20 transfers. Most institutional transfers occurred in the fall months (September, October and November; 62%; n = 13) and males were transferred more often (62%; n = 13). Breeding success (observed copulations) was recorded in 33% (n = 5) of pairs but only 13% (n = 2 pairs) produced offspring during the study period. Institutions with successful breeding pairs had a greater number of indoor, off-exhibit enclosures (2.67 ± 0.29 enclosures; n = 5) compared to facilities with unsuccessful pairs (1.69 ± 0.25 exhibits; n = 6; p = 0.035). In addition, facilities housing successful pairs performed positive reinforcement training more frequently (14.77 ± 3.27 training days/month) than facilities with unsuccessful pairs (4.00 ± 2.73 days/month; p = 0.035). A binomial generalized linear model showed that friendly vocalizations (p = 0.000) during physical introductions of intended breeding pairs predicted copulation success. Introductions performed when a female was exhibiting estrous behavior (p = 0.020), was also predictive of copulation success. Results from this study are the first comprehensive analyses of captive management in the fishing cat. Environmental factors and management approaches are highlighted that could advance animal welfare and improve reproductive success in this species.

Demographic, environmental and genetic determinants of mating success in captive koalas (Phascolarctos cinereus).

Many factors have been shown to affect mating behavior. For instance, genes of the major histocompatibility complex (MHC) are known to influence mate choice in a wide variety of vertebrate species. The genetic management of captive populations can be confounded if intrinsic mate choice reduces or eliminates reproductive success between carefully chosen breeding pairs. For example, the San Diego Zoo koala colony only has a 45% copulation rate for matched individuals. Herein, we investigated determinants of koala mating success using breeding records (1984-2010) and genotypes for 52 individuals at four MHC markers. We quantified MHC diversity according to functional amino acids, heterozygosity, and the probability of producing a heterozygous offspring. We then used categorical analysis and logistic regression to investigate both copulation and parturition success. In addition, we also examined age, day length, and average pairwise kinship. Our post-hoc power analysis indicates that at a power level of 1-β = 0.8, we should have been able to detect strong MHC preferences. However, we did not find a significant MHC effect on either copulation or parturition success with one exception: pairs with lower or no production of a joey had significantly lower MHC functional amino acid diversity in the categorical analysis. In contrast, day length and dam age (or age difference of the pair) consistently had an effect on mating success. These findings may be leveraged to improve the success of attempted pairs, conserve resources, and facilitate genetic management.

Methyl eugenol effects on Bactrocera dorsalis male total body protein, reproductive organs and ejaculate

AbstractMethyl eugenol (ME) and inclusion of protein into the adult diet increase the mating competitiveness of the Oriental fruit fly, Bactrocera dorsalis (Hendel). Exposing males to ME or protein is a promising post‐teneral treatment for males being released in the sterile insect technique (SIT). However, the effect of this post‐teneral treatment on male reproductive organs or the male ejaculate is unknown. During mating, males transfer sperm and accessory gland products (AGPs) to females and these compounds are reported to modulate female sexual inhibition. We studied the impact of male exposure to ME and a yeast hydrolysate (YH) diet on the protein reserves of males, male reproductive organ size, and the male ejaculate through sperm and AGPs. We show that males exposed to ME regardless of access to YH accumulated a greater amount of whole body protein. Males fed on YH also had increased total body protein and had bigger reproductive organs than YH‐deprived males, but no apparent effect of ME exposure was observed on reproductive organ size. Females stored less sperm when mated with males fed on YH and ME compared to males not fed on ME. YH and ME had no effect on male AGPs. Females injected with AGPs of males fed on YH and exposed to ME were just as likely to mate as females injected with AGPs of non‐treated males. However, females injected with AGPs of males exposed to ME mated faster than females injected with AGPs of non‐exposed males. We conclude that while exposure to ME increases male copulatory success and protein reserves in the male body, there seem to be some potential trade‐offs such as lower sperm stored by females. We discuss our results in terms of pre‐release protocols that may be used for B. dorsalis in SIT application.