Occurrence Of Copulation Research Articles

Aversive sexual learning in the kissing bug Rhodnius prolixus: Modulation of different sexual responses in males and females

Although sexual learning can be a key process in the reproductive success of animals, research focused on the experience-dependent modulation of courtship in insects is scarce. In kissing bugs, the behavioural steps implicated in mating have been exhaustively studied, but not the involvement of learning in them. Our objective was to determine whether the sexual behaviour of Rhodnius prolixus could be modulated by experience. During training, couples were submitted to eight assays, in which they received a vibration (negative reinforcement) when the male attempted to copulate the female. Immediately after, they were separated, not allowing the occurrence of copulation. We found that along training, males’ latency to perform a copulatory attempt increased, male’s copulatory attempts were less frequent, and females’ locomotor activity did not change. These results suggest that males, and not females, learned to avoid the vibration by reducing their intention to copulate. In post-training tests, conditioned males presented with new naïve females reverted to low copulatory attempt latencies, suggesting that the modulation was partner-specific. Besides, conditioned females increased their rejection frequencies to males’ copulatory attempts, suggesting that a second type of learning occurred in females. These results constitute the first evidence of sexual learning in hematophagous insects. Males and females seem to change their selectivity according to their previous sexual experience. We discuss the relevance that this plasticity might have in the fitness of this epidemiologically relevant insect.

Impact on reproductive performance and body condition in a small limpet parasitized by a large castrator pea crab.

Parasitic castrators utilize the energy reserves that the host allocates on reproduction resulting in sterilization of the host. However, whether other processes (e.g., growth) are also impaired depends on the balance between the castrator's energy requirements and the available resources that the castrated host does not use in reproduction. We investigated whether the castrator pea crab Calytraeotheres garthi alters body condition, reproductive performance, and occurrence of copulation in its limpet host Bostrycapulus odites. For this purpose, we examined the anatomy of the ovary, the seminal receptacles, and the body condition of parasitized and unparasitized limpets. The histology of the female gonad of parasitized limpets revealed the ovarian tubules are smaller and characterized by a greater proportion of intertubular and intratubular free space compared with non-parasitized individuals. The body condition of female limpets from all sizes (during summer) and those larger than ~16 mm (during spring and autumn) were impacted by the pea crab. These results are in contrast to that previously reported in the comparatively larger limpet species Crepidula cachimilla, in which the same pea crab species does not alter or even increase the host body weight. We concluded this pea crab species could drastically impair its host's reproduction and body condition although deleterious effects are species-specific and likely depend on limpet body size. The histology of seminal receptacles revealed an uncommon disposition of spermatozoa (i.e., excessive debris and acrosomes detached from epithelium) in seminal receptacles of some parasitized limpets. However, this analysis failed to determine whether sperm derived from present matings or previous pea crab infection. Further studies are needed to address whether pea crabs interfere with the mating behavior of limpets and if the alterations in sperm disposition are a consequence of castration.

Effect of size on fighting and mating in a brachyuran crab with female-biased size dimoprohism, Ilyograpsus nodulosus(Macrophthalmidae)

The effect of body size on fighting and mating were examined in both sexes of the rare, Japan-endemic crab Ilyograpsus nodulosus (Sakai, 1983) (Macrophthalmidae), a species in which females are larger than males (female-biased size dimorphism). We found that male-male fights were more common than female-female fights; and that fights between males that were closely size-matched were more common than those between males that were disparate in size. When there was a small size difference between the fighting males, larger and smaller crabs were equally likely to win. When there was a large size difference between the fighting males, the larger crab was more likely to win. Neither male nor female body size predicted the occurrence of copulation. In copulating pairs, male size was positively correlated with female size. Copulation duration decreased with female size. In a female choice experiment, female more often copulated with the larger of the two presented males. In a male choice experiment, males had no preference for the larger or the smaller female. When a single female was placed in a tank with four different sized males, males of all sizes first approached the female and males of all sized copulated, indicating that there was no advantage to large male size in scramble competition. There appears to be a small overall benefit to being a large female and no benefit to being a large male in this species. Male mating success appears to be based on encountering females rather than being successful in male-male competitions or being preferred by females.

Reproductive isolation and sex-role reversal in two sympatric sand-dwelling wolf spiders of the genus Allocosa

Allocosa brasiliensis (Petrunkevitch, 1910) is a nocturnal wolf spider inhabitant of coastal dunes. Pitfall-trap data suggested the occurrence of two sympatric and synchronic morphs, with differences in adult size and abdominal design (minor and major morphs). Previous studies performed with the major morph of A. brasiliensis, postulated courtship-role and sexual size dimorphism reversal for this spider. In the present study, we compare data on development and morphology and test reproductive isolation between morphs of A. brasiliensis, with the hypotheses that the two morphs are reproductively isolated and both show courtship-role reversal. As had been reported for the major morph of A. brasiliensis, the minor-morph females approached the burrows of minor-morph males, entered, initiated courtship, and after copulation, males closed their burrows with female cooperation from the inside. Females did not court or copulate with males belonging to the other morph and, in two cases, major-morph females cannibalised minor-morph males. Morphometrical and developmental data showed differences between morphs. The occurrence of copulation only between individuals of the same morph confirm reproductive isolation, supporting the occurrence of two species. Morphological and behavioural data are consistent with courtship-role-reversal hypotheses for the minor morph, constituting the second report in spiders of this atypical behaviour.

Female sexual preferences differ inMus spicilegusandMus musculus domesticus: the role of familiarization and sexual experience

Mating systems correspond to particular ecological conditions and result from proximate interactions between individuals. We compared the mating preferences of female mice of two species: the house mouse,Mus musculus domesticus, and the mound-builder mouse,Mus spicilegus. Because of differences in their habitat, we expected to observe differences in their sexual preferences. We studied female preferences for a familiar or an unfamiliar male and the occurrence of copulation with the unfamiliar male, during two states of female sexual activity: (1) the postpartum oestrus of paired females, to evaluate the stability of their sexual partnership; and (2) the oestrus of females familiarized with a male, to study the mechanisms underlying their sexual preferences. In the polygamous house mouse, postpartum oestrous females did not show a clear preference between their familiar male and the unfamiliar one. Moreover, oestrous females, familiarized with a male (without sexual interactions), preferred an unfamiliar male and copulated with him. In contrast, postpartum oestrous females and oestrous females ofM.spicileguspreferred their familiar male and rarely copulated with the unfamiliar male. This study indicates a strong pair bond in established breeding pairs inM.spicilegusand shows that this bond can be established by familiarization, which is not the case inM.m. domesticus. Our study suggests the existence of monogamous traits inM.spicilegusin contrast to the polygamousM.m. domesticus.

Evidence of Actual Copulation in the Burrow in the Fiddler Crab, Uca Lactea (De Haan, 1835) (Decapoda, Brachyura, Ocypodidae)

A total of 205 Uca lactea females, which were reared in the laboratory for more than two months without the presence of males, were used to determine if crabs copulate in males' burrows. The females were released in the field and were enticed by courting males into their burrows. Pairs in the burrows were caught after 24 minutes or more. The occurrence of copulation in males' burrows was proven by the presence of spermatophores in the vagina. About 60% of the females were inseminated two hours after staying in males' burrows.

Timing of copulation in the molting and reproductive cycles in a grapsid crab, Gaetice depressus (Crustacea: Brachyura)

From the seasonal changes in the amount of semen in the sperm ducts of males and in the fullness of spermatheca of females, the copulation season of Gaetice depressus in central Japan is considered to approximately coincide with the oviposition season, from March to October. The sperm ducts of all the large males examined contained semen, the amount of which did not vary obviously with stages of the molt cycle or with seasons. The genital apertures of females were normally covered with calcified immobile opercula in this species. The opercula decalcified after molting and again shortly before oviposition, and retained mobility for 1 to 3 d. Shortly after molting, soft-shelled females with mobile opercula did not have well-developed ovaries nor did they copulate with males even if they had a chance. In contrast, all of the hard-shelled females with mobile opercula had well-developed ovaries, and laid eggs within 2 d after the decalcification of opercula regardless of the occurrence of copulation. Laboratory experiments showed that the females normally copulated with males before oviposition. Crabs examined in this study were collected from Shirahama, Wakayama Prefecture, Japan between March 1988 and March 1989.

Occurrence of extra-pair copulation in the tree swallow (Tachycineta bicolor)

A new method to mark sperm transfer events between birds, using microspheres inserted into males' cloacae, was employed to assess the frequency of extra-pair copulation (EPC) in a population of tree swallows (Tachycineta bicolor) in Ontario, Canada, during the summer of 1988. We inserted 25 males with microspheres; spheres from 8 (32%) of these males were found in extra-pair females, from which we infer that males pursue a mixed reproductive strategy of monogamy coupled with seeking EPCs. The cloacae of 10 of 41 (24.4%) females were found to contain microspheres from non-mates. EPCs occur more frequently between neighboring birds than between non-neighbors. Only two within-pair copulations were detected with this method, suggesting that it underestimates the occurrence of all copulations, extra-pair or within-pair. Copulation watches revealed that within-pair copulations occur very frequently. We propose that frequent pair copulations are used by males to ensure their paternity in their mate's offspring.

No evidence for illegitimate young in monogamous and polygynous warblers

In animals with internal fertilization, paternity is uncertain. In birds, the occurrence of copulations outside the pair-bond has been documented in a number of species, but the extent to which these result in illegitimate young is largely unknown, and constitutes a major deficiency in our understanding of avian mating systems. The analysis of tandemly repeated sequences (minisatellites), has enhanced our ability to make individual identifications and paternity determinations. Here we describe the use of a bird minisatellite DNA probe in assigning paternity in natural populations of the monogamous willow warbler Phylloscopus trochilus and of the polygynous wood warbler Phylloscopus sibilatrix. In both species this probe detects a multiple locus pattern and a single locus that exhibits a variable number of tandem repeats. Although we observed intrusions by non-resident males into the territories of paired males and extra-pair copulations, no illegitimate offspring were detected among 176 young from 32 families of both species, implying that extra-pair copulations have little or no genetic impact.

Induction of copulatory behavior in castrated female and male arctic foxes

The aim of the study was to test if it is possible to induce complete copulatory behavior in castrated Arctic foxes ( Alopex lagopus) of both sexes for the purpose of other experiments. Two groups of castrated, sexually experienced Arctic foxes, four pairs in Experiment 1 (a pilot study) and eight pairs in Experiment 2, were treated with different regimes of hormone (estrogens and progesterone in females, testosterone in males). The animals were than tested for copulatory behavior. Nine out of 12 castrated bitches and 10 out of 12 castrated males displayed copulatory behavior during the season of reproductive quiescence for intact Arctic foxes. All the treatments induced complete copulatory behavior (i.e., copulation leading to locking) at least in some animals of both sexes. Examination of results for individual animals suggested that copulatory performance was influenced by preference for specific partners. Also the occurrence of copulation in an early test facilitated its reoccurrence on a later test in the same day with a different partner.

Intracranial sites regulating the biphasic action of progesterone in estrogen-primed golden hamsters.

Diencephalic and mesencephalic neural sites regulating the biphasic effect of progesterone (P) were investigated using the hormone implantation technique in ovariectomized female golden hamsters primed with estrogen. Double barreled cannulae were implanted unilaterally and bilaterally in the medial preoptic area, anterior hypothalamus, ventromedial hypothalamus (VMH), central gray, or interpeduncular nucleus. Testing was conducted using a sequential paradigm; facilitation tests commenced after 44 h of estrogen priming. P-filled cannulae placed in the VMH region facilitated lordosis behavior in 42% and 60% of unilaterally and bilaterally implanted females, respectively. In the anterior hypothalamus, only P implants adjacent to the VMH area effectively promoted receptivity. Lordosis behavior was also observed in 20-36% of females with P implants in the medial preoptic area. P implants in central gray and interpeduncular nucleus regions had no significant facilitating effect on sexual behavior. Tests for inhibition occurred 24 h after facilitation testing and consisted of a pretest, followed by systemic P administration and a behavioral test 4-5 h later. During the pretest for inhibition, females that were receptive in the facilitation test attacked males more rapidly than previously nonreceptive animals and showed decrements in lordosis scores after systemic P delivery. This biphasic effect of P completely inhibited receptivity among several animals in the VMH group. Additional experiments, however, investigating the biphasic effect of P implants in the VMH suggested that the occurrence of copulation in the facilitation test may have been involved in mediating the subsequent increase in aggressive behavior and the suppression of sexual responsiveness in the inhibition test. Nevertheless, a final experiment showed that when P was implanted sequentially in the VMH, facilitation and, more importantly, a later reduction in lordosis behavioral scores occurred even when copulation was eliminated in the facilitation test. P implants in mesencephalic regions exerted no significant inhibitory effect on receptivity. These findings demonstrate that the biphasic action of P in the female hamster is regulated by nerve cells located in the diencephalon, especially in the VMH region.

The effectiveness of sampling methods in detecting copulatory behavior in Macaca arctoides.

The copulatory behavior of a social group of 18 stumptail macaques was observed for 171 hours over a period of 5 months. The occurrence of copulation and several quantitative measures of copulation were compared using sampling periods of 2 hours daily and continuous dawn-to-dusk observation. In this environment copulation was found to occur in brief bouts of relatively short duration. Copulation was detected on 34% of the days observed with 2 hr sampling and 100% of the days with DTD sampling. Thus, brief limited-time samples of behavior are not adequate for reliably detecting copulation in this species under social group-living conditions.

Behavioural changes associated with oestrus in the Giant panda

The Giant panda Ailuropoda melanoleuca has been the subject of many scientific and popular treatises since the first Chinese writings of the seventh century AD. More recent publications have continued to review both facts and fancy concerning the life history and behaviour of this species (Morris & Morris, 1966; Collins & Page, 1973; Davis, 1973; Perry, 1973; Sheldon, 1975). Yet we remain largely ignorant of some of the most essential aspects of Giant panda behaviour, except at a descriptive level. The most thorough treatment of reproduction in A. melanoleuca has been published by the Peking Zoo (Anon, 1974). Reported behavioural changes associated with oestrus and breeding between March and May include greater activity in both sexes, decreased food consumption, especially by the 9, increased urination by the S, and the occurrence of a 'bleat' vocalisation in both sexes (Morris & Morris, 1966; Anon, 1974). As oestrus approaches, the vaginal orifice becomes red and swollen and the $ may rub the genital region with the paw or on objects. Descriptions of copulation suggest that it is short and that the (? may be in a half-seated position behind the 9 (Anon, 1974). This report documents some aspects of the development of socio-sexual behaviour in a pair of Giant pandas at the National Zoological Park, Washington. Data are presented on behavioural changes in the $ and 9 associated with the breeding season and oestrus. Of most importance, however, we will report on the predominance of 9 'preceptive' behaviour (Beach, 1976), which suggests that the $ Giant panda has an extremely active role in initiating and controlling the interactions of the pair prior to mating. The importance of $ activities in influencing the time and occurrence of copulation until recently has generally been ignored (Doty, 1974; Beach, 1976).

Activation of Masculine Sexual Behavior by Intracranial Estradiol Benzoate Implants in Male Rats

Intracranial implants of estradiol benzoate (EB) were used to explore sites of action for the activation of masculine copulatory behavior in castrated male rats. In experiment 1, 27 or 30 gauge implants were placed unilaterally throughout the hypothalamus and preoptic area. Dihydrotestosterone (DHT) was administered subcutaneously (s.c.) to each male. 25 of 42 males with EB implants located in the medial anterior hypothalamic-preoptic area (AHPOA) exhibited ejaculatory patterns on at least 40% of the post-implantation tests. In contrast, only 4 of 18 of the males with implants located posterior to the anterior hypothalamic area displayed this level of response. This difference in the proportion of animals responding for each implant group was statistically significant. Seminal vesicle weights were not correlated with the occurrence of copulation. In experiment 2, either EB-filled or empty cannulae were placed unilaterally in the AHPOA. Half of the males of each group also received DHT s.c. Intracranial EB in conjunction with DHT s.c. resulted in a significantly greater frequency of ejaculatory response than any other treatment. Despite significant differences among the groups in seminal vesicle weights, there was no correlation with occurrence of ejaculatory behavior. These results are consistent with the hypothesis that testosterone (T) exerts its effects upon masculine sexual behavior via conversion to estradiol (E2); and that the principal neural site of action is the AHPOA.

Sexual behavior of captive lowland gorillas

One of the more enduring issues in the study of sexual behavior concerns the degree to which this activity is regulated by hormones. In his early review of this subject, Beach (1942) concluded that, across phylogeny, species with relatively greater encephalization developed greater cognitive control over behavior and a decreased behavioral dependence on hormones. At the time Beach proposed his hypothesis, there had been few systematic laboratory studies conducted on the more advanced species and among the apes, only the chimpanzee having been investigated (Yerkes and Elder, 1936; Yerkes, 1939). The results of these latter studies indicated that chimpanzees, in general, copulated at all phases of the female's sexual cycle, but also that the preponderance of sexual activity occurred during a 10-day midcycle period of maximal female genital swelling. The concordant increase in copulation with genital swelling suggested that hormones were influencing sexual behavior of this species, whereas the occurrence of copulation at phases other than.midcycle indicated at least some degree of behavioral independence from hormones. Therefore, based on the chimpanzee data, the great apes appeared to display an emancipation from hormonal regulation of sexual behavior commensurate with their taxonomic affiliation with man. Clearly, evaluation of the phyletic status of a taxonomic family, such as the great apes, requires data on more than a single species in order to define which of the characteristics of interest pertain to the family as a whole and which pertain only to the particular species studied. There is still a paucity of information in the literature related to sexual behavior of the other two great apes, gorilla and orangutan, and that which pertains to the gorilla was derived primari-

Notes on the breeding habits of the nudibranchs of Monterey bay and vicinity

AbstractData concerning the seasonal distribution of twenty‐two species of nudibranchs are recorded for a period of 9 months. The occurrence of copulation and of egg laying for these animals in the laboratory aquaria is recorded for the same period. These data indicate that the seasonal distribution of certain species is well marked, and that there is in many cases a definite breeding season.The characteristics of the egg ribbons of these nudibranchs are described, and figured by means of photographs. These egg ribbons approach the mathematical form of a spiral of Archimedes. In every case observed, the ribbon was deposited in a counter‐clockwise direction, viewed dorsally.The relationship between these observations and earlier work on the life histories of the nudibranchs is discussed.