Copulation Attempts Research Articles

Individual Variation in Male Size and Behavioral Repertoire in the Sailfin Molly Poecilia latipinna

AbstractVariation among individuals in the expression of behaviors and associations of behaviors in different contexts can lead to the maintenance of behavioral polymorphisms. Individual variation in morphology is often associated with behavioral polymorphism, yet the degree to which morphology predicts behavioral phenotype is not well understood. We measured individual variation in size and behaviors in the sailfin molly, Poecilia latipinna, by comparing the behavior of individual males of different sizes across four different contexts (mating, exploratory tendency, sociability, and predator inspection). We also investigated the degree to which male size, a fixed genetic trait, influenced the expression of each behavior and associations between behaviors. We found that male mollies show strong associations between certain behaviors and only some of these are predicted by male size. For example, size has a strong influence on the courtship‐boldness axis with larger males showing higher rates of courtship displays and being bolder in predator inspection. A positive association was found between exploratory tendency, sociability, and gonopodial thrusting rates, yet the expression of these behaviors was independent of male size. Thus, sailfin mollies, like many fish species, show associations of behaviors that contribute to differences among males in personality type. The fixed genetic effect of male size at maturity influences courtship and boldness, but individual variation in exploratory tendency, sociability, and sneak copulation attempts through gonopodial thrusts is independent of male size. Such variation among males in behavioral associations within and between different contexts may slow the rate at which populations of P. latipinna can diverge in individual behaviors.

Ultrasonic courtship song of the yellow peach moth, Conogethes punctiferalis (Lepidoptera: Crambidae)

Although generation of ultrasound during courtship has been reported for an increasing number of moth species, the effect of the ultrasound on mating remains uncertain in many cases because of a lack of proper verification. Here we report that males of the yellow peach moth Conogethes punctiferalis (Crambidae) sexually communicate with females by emitting loud ultrasound (103 dB peak equivalent sound pressure level at 1 cm; dominant frequency 82 kHz) before attempting copulation. The male ultrasound consists of consecutive clicks (pulses) in the early phase of the sound train and consecutive pulses (burst) in the late phase. When females were deafened by puncturing the abdominal tympanic membranes, copulation never occurred. We found that deafened females did not assume the wing-raising posture, which, for normal pairs, always precedes successful copulation. Our findings indicate that male courtship ultrasound evokes wing-raising as an acceptance behavior from females, which in turn evokes a copulation attempt by a male.

Drosophila female precopulatory behavior is modulated by ecdysteroids

The effect of ecdysteroid signaling on Drosophila female precopulatory behavior was investigated using two types of mutants with either globally reduced ecdysteroid availability or reduced expression of ecdysone receptors in fruitless neurons, known to control sexual behavior. While being courted by males, mutant females performed significantly less full ovipositor extrusion behavior to reject male copulation attempts. Ecdysteroid depleted females (ecdysoneless1) performed male-like courtship behaviors, including unilateral wing extension and song production with patterns very similar to male courtship song. These results support the hypothesis that ecdysteroids modulate female sexual behavior, perhaps acting as a regulator of sexual motivation, and as a component affecting the performance of sex specific behavior patterns.

The dynamics of male-male competition in Cardiocondyla obscurior ants

BackgroundThe outcome of male-male competition can be predicted from the relative fighting qualities of the opponents, which often depend on their age. In insects, freshly emerged and still sexually inactive males are morphologically indistinct from older, sexually active males. These young inactive males may thus be easy targets for older males if they cannot conceal themselves from their attacks. The ant Cardiocondyla obscurior is characterised by lethal fighting between wingless (“ergatoid”) males. Here, we analyse for how long young males are defenceless after eclosion, and how early adult males can detect the presence of rival males.ResultsWe found that old ergatoid males consistently won fights against ergatoid males younger than two days. Old males did not differentiate between different types of unpigmented pupae several days before emergence, but had more frequent contact to ready-to-eclose pupae of female sexuals and winged males than of workers and ergatoid males. In rare cases, old ergatoid males displayed alleviated biting of pigmented ergatoid male pupae shortly before adult eclosion, as well as copulation attempts to dark pupae of female sexuals and winged males. Ergatoid male behaviour may be promoted by a closer similarity of the chemical profile of ready-to-eclose pupae to the profile of adults than that of young pupae several days prior to emergence.ConclusionYoung ergatoid males of C. obscurior would benefit greatly by hiding their identity from older, resident males, as they are highly vulnerable during the first two days of their adult lives. In contrast to the winged males of the same species, which are able to prevent ergatoid male attacks by chemical female mimicry, young ergatoids do not seem to be able to produce a protective chemical profile. Conflicts in male-male competition between ergatoid males of different age thus seem to be resolved in favour of the older males. This might represent selection at the colony level rather than the individual level.

Blood corticosterone levels and intersexual selection games: best-of-bad-job strategies of male common lizards

Glucocorticoids affect physiology and behaviour, reproduction and potentially sexual selection as well. Short-term and moderate glucocorticoid elevations are suggested to be adaptive, and prolonged and high elevations may be extremely harmful. This suggests that optimal reproductive strategies, and thus sexual selection, may be dose dependent. Here, we investigate effects of moderate and high elevations of blood corticosterone levels on intra- and intersexual behaviour and mating success of male common lizards Lacerta vivipara. Females showed less interest and more aggressive behaviour towards high corticosterone males and blood corticosterone levels affected male reproductive strategy. Males of moderate and high corticosterone elevations, compared with Control males, showed increased interest (i.e., higher number of chases, tongue extrusions, and approaches) towards females and high corticosterone males initiated more copulation attempts. However, neither increased male interest nor increased copulation attempts resulted in more copulations. This provides evidence for a best-of-a-bad-job strategy, where males with higher corticosterone levels compensated for reduced female interest and increased aggressive female behaviour directed towards them, by showing higher interest and by conducting more copulation attempts. Blood corticosterone levels affected intrasexual selection as well since moderate corticosterone levels positively affected male dominance, but dominance did not affect mating success. These findings underline the importance of female mate choice and are in line with adaptive compensatory behaviours of males. They further show that glucocorticoid effects on behaviour are dose dependent and that they have important implications for sexual selection and social interactions, and might potentially affect Darwinian fitness.

Courtship and mating behaviour in the fruit fly parasitoid Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae): the role of wing fanning

Psyttalia concolor is a parasitoid of fruit flies (Tephritidae) which is used to control the olive fruit fly (Bactrocera oleae). Detailed knowledge of its reproductive biology is required to optimise mass rearing conditions and use in biological control. In this study, the mating behaviour of P. concolor was investigated in order to understand the factors that can influence the success of male mating, using both high-speed video and biological assays. P. concolor males were more likely to be successful in mating during the early morning as opposed to the afternoon, and their courtship behaviour was not affected by the female mating status (i.e. virgin or mated). Wing fanning and copulation attempts were also frequently displayed among males, but male mating status did not influence male–male courtship behaviour. Video data revealed that during wing fanning, male wings were kept raised and moved rhythmically in a dorsoventral fashion. Frequency, pulse duration and interpulse interval of the fanning males during female courtship differed significantly in successful mating attempts compared to unsuccessful ones. Wingless males had significantly lower mating success compared to winged males, suggesting that wing fanning increases the likelihood of attracting a mate. Overall, the study increases the knowledge of the reproductive biology of P. concolor and suggests the importance of fanning behaviour among the range of sensory modalities used by this parasitoid in intra-specific communication.

Copulatory Courtship Behavior and Sine Song as a Mate Recognition Cue inDrosophila liniand Its Sibling Species

Most Drosophila species sing species-specific pulse songs during their "precopulatory courtship." Three sibling species of the Drosophila montium species subgroup performed "copulatory courtship": males generated courtship songs by vibrating either wing only after mounting and during copulation. In these three species, strong sexual isolation was detected between D. ohnishii and D. lini and between D. ohnishii and D. ogumai, but not between D. lini and D. ogumai. Female showed strong repelling behavior when they were mounted by a heterospecific male in the species combinations including D. ohnishii, resulting in failure of the copulation attempt of the male. Acoustic analyses of courtship songs revealed that the pulse song was irregular, without any species-specific parameters, but that the frequency of the sine song was different among the three species in accordance with the modes of sexual isolation between them; it was significantly lower in D. ohnishii (mean ± SE = 193.0 ± 1.7 Hz) but higher in D. lini (253.4 ± 2.7 Hz) and D. ogumai (246.7 ± 5.3 Hz). We suggest that this difference in the sine song frequency is a sexual signal in the Specific Mate Recognition System (SMRS) among these three Drosophila species.

A Single Sex Pheromone Receptor Determines Chemical Response Specificity of Sexual Behavior in the Silkmoth Bombyx mori

In insects and other animals, intraspecific communication between individuals of the opposite sex is mediated in part by chemical signals called sex pheromones. In most moth species, male moths rely heavily on species-specific sex pheromones emitted by female moths to identify and orient towards an appropriate mating partner among a large number of sympatric insect species. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component, (E, Z)-10,12-hexadecadienol (bombykol), is sufficient to elicit full sexual behavior. We have previously shown that the sex pheromone receptor BmOR1 mediates specific detection of bombykol in the antennae of male silkmoths. However, it is unclear whether the sex pheromone receptor is the minimally sufficient determination factor that triggers initiation of orientation behavior towards a potential mate. Using transgenic silkmoths expressing the sex pheromone receptor PxOR1 of the diamondback moth Plutella xylostella in BmOR1-expressing neurons, we show that the selectivity of the sex pheromone receptor determines the chemical response specificity of sexual behavior in the silkmoth. Bombykol receptor neurons expressing PxOR1 responded to its specific ligand, (Z)-11-hexadecenal (Z11-16:Ald), in a dose-dependent manner. Male moths expressing PxOR1 exhibited typical pheromone orientation behavior and copulation attempts in response to Z11-16:Ald and to females of P. xylostella. Transformation of the bombykol receptor neurons had no effect on their projections in the antennal lobe. These results indicate that activation of bombykol receptor neurons alone is sufficient to trigger full sexual behavior. Thus, a single gene defines behavioral selectivity in sex pheromone communication in the silkmoth. Our findings show that a single molecular determinant can not only function as a modulator of behavior but also as an all-or-nothing initiator of a complex species-specific behavioral sequence.

Age-related dominance helps reduce male aggressiveness in great bustard leks

Stable dominance hierarchies have evolved in many socially living animals to reduce the negative consequences of agonistic interactions. To evaluate whether established dominance relationships reduce aggressive encounters among males during the mating season, we studied aggressive behaviour in lekking male great bustards, Otis tarda. This sexually dimorphic bird species is potentially subject to strong sexual selection operating through intramale competition. The strongly skewed mating success of males is mainly determined by their age and weight, which are reliably signalled through plumage traits. We observed that adult males lived in stable groups at traditional leks to which they remained faithful throughout their lives, a prerequisite for the establishment of stable dominance hierarchies. Males substantially reduced aggressive interactions during the mating period. Males involved in more aggressive interactions during the premating period had weakly expressed sexual traits and low courtship success, which suggests the existence of an age- and possibly also weight-determined lek hierarchy. This is supported by the increase with age in a male’s dominance index, and the absence of aggressive interactions at advanced ages. During the mating period, older males and those with higher courtship success were involved in fewer aggressive encounters, suggesting that other males respected their status. Subdominant males disrupted other males’ copulation attempts, perhaps to reduce their success or to gain copulations themselves. Our study supports the hypotheses that social dominance is largely age determined in the great bustard and that established dominance relationships help reduce intramale aggression during the mating period.

Validation of a Method for Quantifying Male Mating Preferences in the Guppy (Poecilia reticulata)

Male and female mating preferences are commonly inferred from association times spent with potential mates in a dichotomous-choice test. However, this assessment method is rarely validated, particularly so for male mating preferences. Using the Trinidadian guppy (Poecilia reticulata), an important model species in the study of sexual selection, we tested whether a male’s mating preference for either of two stimulus females in a dichotomous-choice test predicted his mating behaviours directed at the preferred female when he was allowed to swim freely with both females. First, we presented individual males with two females that differed in body length in a dichotomous-choice apparatus in which the male could only use visual cues to assess the paired females. We quantified male mating preference as the duration of time a focal male spent associating with each female. Immediately following this test, the focal male was allowed to swim freely with both females, and we quantified the time he spent sexually pursuing each female and the number of courtship sigmoid displays and copulation attempts he directed at each female. On average, males did not significantly prefer either of the two stimulus females in either of the two tests; however, the magnitude of male preference for the larger female tended to increase as the size difference between the paired females increased. More importantly, there was a significant positive relationship between male association time in the dichotomous-choice test and both the time spent sexually pursuing and the number of courtship sigmoid displays directed at the same female initially preferred in the dichotomous-choice test. Collectively, these results confirm that association time measured in a dichotomous-choice test is a reliable predictor of male mating preferences in the Trinidadian guppy.

Teneral matings in fruit flies: male coercion and female response

Extensive research indicates that sexually mature female fruit flies typically choose with whom to mate, a process that is crucial for the operation of sexual selection and population divergence via female choice. We followed up on field data suggesting that male fruit flies (Drosophila melanogaster) force copulate with teneral females, which are recently eclosed females characterized by their folded wings and soft, light coloured bodies. Our results indicated that males succeeded in mating with about 20% of the teneral females from our Canton-S population and 15% of the teneral females from a local, wild-caught D. melanogaster population. Males were most likely to mate with recently eclosed females and failed to mate with females older than 1 h posteclosion. Close behavioural observations indicated coercion by the males and resistance by the teneral females. The teneral females continued to fight off males throughout copulation and this probably contributed to the shorter mating duration of teneral females relative to that of mature females. Although teneral females failed to foil some forced copulation attempts, they could reduce the impact of such copulations by subsequently remating with a male of their choosing. Indeed, tenerally mated females were six times more likely to remate than were control females that had mated when mature. Our results substantiate a novel aspect of sexual conflict in fruit flies, which could counteract processes driven by female mate choice.

Sex Differences in Mate Preference Between Two Hybridizing Species of Poeciliid Fish

When hybridization between two species in secondary contact is costly, natural selection should favor pre-mating isolation barriers. The invasive Gambusia affinis has been introduced to habitats of a closely related species, the endangered Gambusia nobilis. Although other Gambusia species readily hybridize in secondary contact, previous studies in this system found low abundance of hybrids in sympatry. To examine whether hybridization is limited by behavioral pre-mating isolation that may have evolved in allopatry, I examined each species’ mating preferences using individuals from allopatric populations in male and female visual/olfactory association preference tests as well as open mating tests with and without male–male competition. Gambusia affinis and G. nobilis males had significant association preference for conspecific females in visual/olfactory tests. Only G. nobilis females had statistically significant preference for conspecific males. In open mating tests, males of both species had lower chase times overall when in competition, but there was no difference in number of copulation attempts. Males of both species had higher copulatory success rates with conspecific females when in competition, suggesting females may exert some control over copulation success of males. These results suggest that there are differences in mating preferences between these species. This mate choice may act as a pre-mating isolating barrier to reduce hybridization in sympatry, a proposed threat to the endangered G. nobilis.

Insect quality control: synchronized sex, mating system, and biological rhythm

The sterile insect technique (SIT) is a method of eradicating insects by releasing mass-reared sterilized males into fields to reduce the hatchability of eggs laid by wild females that have mated with the sterile males. SIT requires mass-production of the target insect, and maintenance of the quality of the mass-reared insects. The most important factor is successful mating between wild females and sterile males because SIT depends on their synchronized copulation. Therefore, understanding the mating systems and fertilization processes of target insects is prerequisite. Insect behavior often has circadian rhythms that are controlled by a biological clock. However, very few studies of relationships between sterile insect quality and circadian rhythm have been performed compared with the amount of research on the mating ability of target insects. The timing of male copulation attempts with receptivity of females is key to successful mating between released males and wild females. Therefore, we should focus on the mechanisms controlling the timing of mating in target insects. On the other hand, in biological control projects, precise timing of the release of natural enemies to attack pest species is required because behavior of pests and control agents are affected by their circadian rhythms. Involving both chronobiologists and applied entomologists might produce novel ideas for sterile insect quality control by synchronized sex between mass-reared and wild flies, and for biological control agent quality by matching timing in activity between predator activity and prey behavior. Control of the biological clocks in sterile insects or biological control agents is required for advanced quality control of rearing insects.

Forced copulation attempt in the Blue-tailed Lizard, Micrablepharus maximiliani (Reinhardt & Luetken, 1862) (Squamata, Gymnophthalmidae) in the Caatinga of Northeastern Brazil

Forced copulation is characterized by jerky and rapid movements performed by a female in an apparent attempt to escape from a mounting male. This short communication reports a forced copulation attempt by the gymnophthalmid lizard Micrablepharus maximiliani in a forest enclave inside the Caatinga biome, Tenente Laurentino Cruz municipality, Rio Grande do Norte, Brazil. The rejection behavior of the female consisted of running, pushing and hiding from the mounting male. Although the causes of female mate rejection remain unclear, it may be possible that on this occasion the female M. maximiliani may not have been reproductively active and/or avoided the male deliberately.

Floral Mimicry Enhances Pollen Export: The Evolution of Pollination by Sexual Deceit Outside of the Orchidaceae

Although the majority of flowering plants achieve pollination by exploiting the food‐seeking behavior of animals, some use alternative ploys that exploit their mate‐seeking behavior. Sexual deception is currently known only from the Orchidaceae and almost always involves pollination by male hymenoptera. An outstanding problem has been to identify the selective factors in plants that favor exploitation of mating versus feeding behaviors in pollinators. Here we show that the insectlike petal ornaments on inflorescences of the daisy Gorteria diffusa elicit copulation attempts from male bombyliid flies and that the intensity of the mating response varies across geographical floral morphotypes, suggesting a continuum in reliance on feeding through mating responses for pollination. Using pollen analogues applied to a morphotype with prominent insectlike petal ornaments, we demonstrate that mate‐seeking male flies are several‐fold more active and export significantly more pollen than females. These results suggest that selection for traits that exploit insect mating behavior can occur through the male component of plant fitness and conclusively demonstrates pollination by sexual deception in Gorteria, making this the first confirmed report of sexual deception outside of the Orchidaceae.

Male water striders attract predators to intimidate females into copulation

Despite recent advances in our understanding of sexual conflict and antagonistic coevolution between sexes, the role of interspecific interactions, such as predation, in these evolutionary processes remains unclear. In this paper, we present a new male mating strategy whereby a male water strider Gerris gracilicornis intimidates a female by directly attracting predators as long as she does not accept the male's coercive copulation attempt. We argue that this male strategy is a counteradaptation to the evolution of the female morphological shield protecting her genitalia from coercive intromission by water strider males. The G. gracilicornis mating system clearly represents an effect expected from models of the coevolutionary arms race between sexes, whereby one sex causes a decrease in the fitness component of the other sex. Moreover, our study demonstrates a crucial role that interspecific interactions such as predation can have in the antagonistic coevolution between sexes.

Methoprene modulates the effect of diet on male melon fly, Bactrocera cucurbitae, performance at mating aggregations

AbstractThe effect of access to dietary protein (P) (hydrolyzed yeast) and/or treatment with a juvenile hormone analogue, methoprene (M), (in addition to sugar and water) on male aggregation (lekking) behaviour and mating success was studied in a laboratory strain of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). Six‐day‐old males were treated with (1) protein and methoprene (M+P+), (2) only protein (M−P+), or (3) only methoprene (M+P−), and compared with 14‐day‐old sexually mature untreated males (M−P−). The lekking behaviour of the four groups of males when competing for virgin sexually mature females (14 –16 days old) was observed in field cages. The following parameters were measured at male aggregations: lek initiation, lek participation, males calling, male–male interaction, female acceptance index, and mating success. For all these parameters, the M+P+ males significantly outperformed the other males. Moreover, for all parameters, there was a similar trend with M+P+ > M−P+ > M−P− > M+P−. More M+P+ males called and initiated and participated in lek activities than all other types of male, which resulted in higher mating success. They had also fewer unsuccessful copulation attempts than their counterparts. Whereas treatment with methoprene alone had a negative effect in young males with only access to sugar, access to dietary protein alone significantly improved young male sexual performance; moreover, the provision of methoprene together with protein had a synergistic effect, improving further male performance at leks. The results are of great relevance for enhancing the application of the sterile insect technique (SIT) against this pest species. The fact that access to dietary protein and treatment of sterile males with methoprene improves mating success means that SIT cost‐effectiveness is increased, as more released males survive to sexual maturity.

Correlates of male mating success in great bustard leks: the effects of age, weight, and display effort

We examined how mating success varied in relation to age, weight, body size, and display behavior among great bustard Otis tarda males. The estimated mating success was strongly skewed, with 45% of adult males being involved in copulation attempts and only 9.7% actually seen copulating successfully. Unlike most birds, body size continued increasing in great bustards several years after reaching sexual maturity. Age, weight, and display effort were all significant and independent predictors of male mating success. The higher display effort involved performing longer full-display bouts. Older males could detach from the male flock earlier in the season as well as on each day and spend longer seasonal and daily periods displaying as solitary birds, which contributed to increase their mating success. In contrast, males weighing more did not invest more in display, which suggests that they could be recognized as dominants by other males and selected by females through assessment of their plumage sexual traits. In contrast to most other bird species, the system described for great bustards resembles that found in some lek-mating ungulates, where social rank is a complex trait determined by both age and mass, and as in these mammals, it suggests that sexual selection continues to favor a high male weight in this extremely sexually dimorphic species.

Veränderungen der sexuellen und aggressiven Handlungsbereitschaft des Schwertträgers Xiphophorus helleri (Pisces, Poeciliidae) unter dem Einfluß sozialer Isolation1,2

Social deprivation for 3 to 112 days caused an increase in copulation attempts and other motivational changes of sexual activities. Furthermore, it could be demonstrated that the tendencies for nipping, backing, copulation attempts, and gonopodial swinging fluctuated independently as a result of non-release of these activities. A rise in copulation tendency does not necessarily lead to increased aggressiveness. In the social hierarchy inferior individuals exhibited the highest levels of sexual and aggressive responsiveness.

Der Anteil des “Coolidge-Effektes” an der isolationsbedingten Zunahme sexueller Verhaltensweisen von Poecilia sphenops*)

Changing the Stimulus ♀ induced in ♂♂ of the poeciliid fish Poecilia sphenops a strong increase of copulation attempts, nipping and gonopodial swinging (“Coolidge effect”). There was a similar increase of sexual activities after social isolation of 23 hours and reintroducing the same ♀ like before. But in experiments it could be demonstrated that the effect of social deprivation can only partly be deduced from the Coolidge effect and seems to be also the result of sexual inactivity during the isolation period.