Suppressed copulatory behavior and ovarian function in lactating Japanese monkeys (Macaca fuscata fuscata) during the mating season

The influence of lactation on copulatory behaviors and ovarian functions was studied in Japanese monkeys (Macaca fuscata fuscata) during the mating season. Three lactating females were housed in an outdoor group cage with their infants, and three nonlactating females were housed in an adjacent outdoor cage. They were mated by introduction of one of four rotationally chosen males into the females' cage, for two hours three times a week; the occurrence of ejaculatory copulations was recorded. Blood samples were collected on each observation day, and plasma levels of estradiol, progesterone, and luteinizing hormone (LH) were measured by specific radioimmunoassays. In nonlactating females, plasma estradiol increased during the transition into the mating season, and rose to levels over 90 pg/ml for the first time on about 50 days before the first ovulation. Shortly after plasma estradiol exceeded 90 pg/ml in the nonlactating females, the onset of ejaculatory copulations occurred. They received ejaculations continuously up to the early ovarian luteal phase. On the other hand, in lactating females, there were lower levels of plasma estradiol (below 90 pg/ml) during the transition into the mating season, and they received no ejaculation during that period. Two of the three lactating females ovulated only once, and they received ejaculations only during the periovulatory period, coinciding with the rise of their plasma estradiol levels over 90 pg/ml. The remaining lactating female remained anovulatory and received no ejaculation throughout the entire mating season. These results have demonstrated that the low sexual activity of lactating females is clearly correlated with low levels of plasma estradiol due to suppressed ovarian function.     

Rearing Temperature Influences Adult Response to Changes in Mating Status

Rearing environment can have an impact on adult behavior, but it is less clear how rearing environment influences adult behavior plasticity. Here we explore the effect of rearing temperature on adult mating behavior plasticity in the butterfly Bicyclus anynana, a species that has evolved two seasonal forms in response to seasonal changes in temperature. These seasonal forms differ in both morphology and behavior. Females are the choosy sex in cohorts reared at warm temperatures (WS butterflies), and males are the choosy sex in cohorts reared at cooler temperatures (DS butterflies). Rearing temperature also influences mating benefits and costs. In DS butterflies, mated females live longer than virgin females, and mated males live shorter than virgin males. No such benefits or costs to mating are present in WS butterflies. Given that choosiness and mating costs are rearing temperature dependent in B. anynana, we hypothesized that temperature may also impact male and female incentives to remate in the event that benefits and costs of second matings are similar to those of first matings. We first examined whether lifespan was affected by number of matings. We found that two matings did not significantly increase lifespan for either WS or DS butterflies relative to single matings. However, both sexes of WS but not DS butterflies experienced decreased longevity when mated to a non-virgin relative to a virgin. We next observed pairs of WS and DS butterflies and documented changes in mating behavior in response to changes in the mating status of their partner. WS but not DS butterflies changed their mating behavior in response to the mating status of their partner. These results suggest that rearing temperature influences adult mating behavior plasticity in B. anynana. This developmentally controlled behavioral plasticity may be adaptive, as lifespan depends on the partner’s mating status in one seasonal form, but not in the other.     

Mating status regulates post‐mating refractory period in Striacosta albicosta females

In polyandrous insect species, males may transfer substances to reduce sperm competition by affecting female sexual receptivity. In this study, we determined the incidence of polyandry in females of Western bean cutworm (WBC), Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), and investigated the influence of both previous female and male mating history on the duration of mating, the female refractory period, and subsequent calling behavior of females under controlled laboratory conditions. The mating status of WBC males influenced mating duration, with copulations involving previously mated males taking longer, possibly related to the time required to produce an ejaculate. The duration of the female refractory period and the onset time of recalling during the scotophase were both affected by female mating history, but not by that of the males. Females had a shorter refractory period and resumed calling activity earlier after their second and third matings than after their first mating. The earlier onset of calling by previously mated females could reduce competition with virgin females and their shorter refractory period could explain the high incidence of polyandry observed in nature.     

Mating Status Effects on Sexual Response of Males and Females in the Parasitoid Wasp <Emphasis Type="Italic">Urolepis rufipes</Emphasis>

Although mate preferences are most commonly examined in females, they are often found in both sexes. In the parasitoid wasp Urolepis rufipes, both female and male mating status affected certain aspects of sexual interactions. Female mating status mattered only in the later stages of mating. Males did not discriminate between virgin and mated females in terms of which they contacted or mounted first. However, once mounted, most virgin females were receptive to copulation, whereas very few mated females were. Whether a male’s mating status affected his own sexual response depended on the female’s ability to respond and the stage of mating. Examining male behavior toward dead females allowed elimination of the role of female behavior in how males responded. Virgin and mated males are both attracted to dead females as evidenced by their fanning their wings at such females. However, mated males were quicker than virgin males to contact and to mount in an experiment with dead females, whereas there was no such differential response in an experiment with live females. This difference is consistent with greater female sexual responsiveness to virgin males. Male mating status also affected female receptivity to copulate. Once mounted, live virgin females were less likely to become receptive to copulation by mated males than to virgin males, but only in a choice experiment, not in a no-choice experiment.     

Effect of multiple mating on the reproductive performance of the rice leaffolder moth,Cnaphalocrocis medinalis (Lepidoptera: Crambidae)

To clarify whether multiple mating of females and males affects the reproductive performance of the rice leaffolder moth, Cnaphalocrocis medinalis (Guenée), we examined the effect of the number of matings (once, twice, or three times) for females (female treatment) and males (male treatment) on the incidence of moth mating, number of eggs laid, egg hatchability, and adult longevity. We also compared the effect of multiple mating imposed on males or females separately with the effect of that imposed on both sexes simultaneously (both sexes treatment). The incidence of mating of females and males that mated three times (3-mated females and males) was significantly lower than for females and males that mated twice or once (2-mated or 1-mated females and males). The incidence of mating of 1-mated moths (both sexes) was significantly higher than for 2-mated or 3-mated moths (both sexes). Two-mated or 3-mated females laid significantly more eggs with significantly higher hatchability than 1-mated females. Females that mated with 1-mated males (second male mating) or 2-mated males (third male mating) laid significantly fewer eggs than those that mated with virgin males (first male mating). Females laid significantly more eggs after the second and third matings for moths of both sexes than after the first mating for moths of both sexes. The mechanisms of improvement and decline of female reproductive performance when multiple mating was imposed on males or females are also discussed in relation to the reproductive biology of C. medinalis.     

Mating behavior of Diabrotica speciosa (Coleoptera: Chrysomelidae)

Diabrotica speciosa (Germar) is an economically important pest of Neotropical cultures and represents a quarantine risk for Neartic and Paleartic Regions. Despite its agricultural importance, few studies have been done on mating behavior and chemical communication, which has delayed the development of behavioral techniques for population management, such as the use of pheromone traps. In this study, we determined 1) the age at first mating; 2) diel rhythm of matings; 3) number of matings over 7 d; 4) the sequence of D. speciosa activities during premating, mating, and postmating; 5) the duration of each activity; and 6) response to male and female conspecific volatiles in Y-tube olfactometer. The first mating occurred between the third and seventh day after adult emergence and the majority of pairs mated on the fourth day after emergence. Pairs of D. speciosa showed a daily rhythm of mating with greater sexual activity between the end of the photophase and the first half of the scotophase. During the 7 d of observation, most pairs mated only once, although 30% mated two, three, or four times. In a Y-tube olfactometer, males were attracted by virgin females as well as by the volatile compounds emitted by females. Neither males nor their volatiles were attractive to either sex. Our observation provide information about mating behavior of D. speciosa, which will be useful in future research in chemical communication, such as identification of the pheromone and development of management techniques for this species using pheromone traps.     

Mating stimulation required for mating-induced estrous abbreviation in female rats: effects of repeated testing

Mating stimulation, particularly vaginal-cervical stimulation, causes estrous abbreviation in female rats. In most previous studies, female rats were repeatedly tested for sexual behavior until estrous termination occurred. Thus, it was not clear whether sensory stimulation (e.g., flank stimulation, olfactory cues) received during the repeated testing procedure contributed to estrous abbreviation. In Experiment 1, we determined the effect of premating to two or four ejaculations on the rate of estrous termination when a repeated testing procedure was used. We compared ovariectomized, hormone-primed, female rats receiving (1) four ejaculations, (2) two ejaculations, or (3) no premating. Females premated to either two or four ejaculations showed significantly lower levels of sexual receptivity 12 h later than did nonpremated females. These results confirm that premating induces estrous abbreviation when a repeated testing procedure is used. In Experiment 2, we determined whether the repeated testing procedure was necessary for estrous abbreviation. Ovariectomized, hormone-primed female rats were premated to two ejaculations or not premated. The rats were then tested for sexual behavior repeatedly or only once. Females that were premated and repeatedly tested for sexual behavior showed a statistically significant decrease in sexual receptivity compared to females that were not premated; however, the level of sexual receptivity in premated females did not differ from that in non-premated females when they were tested only once. The results suggest that heat duration is the result of a complex interplay between those factors that promote the expression of sexual receptivity and those that inhibit it.     

Sexual inhibition of female Queensland fruit flies mated by males treated with raspberry ketone supplements as immature adults

Raspberry ketone (RK) dietary supplements accelerate the emergence of sexual behaviour in developing Queensland fruit fly (Q‐fly) males and show promise as a pre‐release supplement for use in sterile insect technique (SIT) programs. However, the value of RK supplements in SIT programs would be greatly reduced if RK‐treated males are ineffective at inducing sexual inhibition in mated females. To test the effectiveness of matings by RK‐treated males, we here investigate the remating propensity of females mated by RK‐treated (1.25% or 5% RK in food) and RK‐untreated (control) males. Tested males received RK supplements mixed in sugar and yeast hydrolysate for 2 days after emerging and then received only sugar. To test for male age‐dependent effects, virgin females were mated to treated and untreated males that were 6, 8, 10, 20 or 30 days old. To test for persistence of sexual inhibition, mated females were tested for remating propensity at 1, 7 or 15 days after their first mating. RK‐treated males did not differ from control males in copula duration, and females mated by RK‐treated males did not differ from those mated by control males in remating propensity, second copula latency or second copula duration. RK‐treated Q‐fly males not only mate at younger ages but also their matings are as effective as those of untreated controls at inducing sexual inhibition in mates.     

Sexual behavior of male New Zealand white rabbits in an intensive production unit

Sexual behavior in the male white New Zealand rabbit in intensive production units is not fully documented. Therefore, the objective of this work was to provide further information about the sexual behavior of this species in intensive production systems. Fourteen 6- to 12-month-old rabbits were studied for 6 months (July/December) when housed individually under natural photoperiod (19 degrees latitude north). They were mated once a week. When mated they were exposed at 6-min intervals to five oestrous females. The number of mounts, time between mounts, time and number of ejaculations, time between ejaculations, and also enuresis, grasping and kicking were recorded. Mounts (n=222) were observed and recorded. Males mated one to five times during each evaluative session. Enuresis was present only in one observation. Sexual aggressiveness such as grasping and kicking was present during 142 and 133 matings. Time for mounting and ejaculation in accumulated means (minutes, seconds, tenths) from the first to the fifth mount were noted and an accumulative average of 4.20 min for the fifth mounting was noted. Minimum times for ejaculation and next mating was 00:17:00 min and maximum was 05:33:03 min. It was concluded that sexual behavior in white New Zealand male rabbits remained unchanged through the duration of the period of study.     

Spermatophore and Sperm Allocation in Males of the Monandrous Butterfly Pararge aegeria: the Female’s Perspective

In insects, spermatophore production represents a non‐trivial cost to a male. Non‐virgin males have been shown to produce small spermatophores at subsequent matings. Particularly in monandrous species, it may be an issue to receive a sufficiently large spermatophore at the first and typically only mating. Females of the monandrous Speckled wood butterfly Pararge aegeria (L.) produce fewer offspring after mating with a non‐virgin male. After mating, females spend all their active time selecting oviposition sites and typically ignore other males. Here, we show that females did not discriminate between a virgin male and a recently mated male in our laboratory experiments. We demonstrate that the number of eupyrene sperm bundles relative to spermatophore mass differed with subsequent male matings. Males transferred a significantly smaller spermatophore after the first copulation, but the spermatophore mass did not decrease further with subsequent matings. However, the number of eupyrene sperm bundles decreased linearly. Therefore, there was proportionally more eupyrene sperm in the male’s second spermatophore compared with the first and the later spermatophores. Such a pattern has been shown in polyandrous species. Hence, it suggests that differences in sperm allocation strategy between polyandrous and monandrous butterflies may be quantitative rather than qualitative. There was also a tendency for females that had mated with a recently mated male to have higher propensity to remate than did females that had mated with a virgin male. We discuss the results relative to the mating system in P. aegeria, including female remating opportunities in the field and male mate‐locating behaviour.     

Adrenalectomy: Effects on mating behavior,ovulation, and early gestation in the cycling rat

Adrenalectomy was performed 4 weeks prior to evaluating the effects on mating behavior, ovulation, and the first 10 days of gestation in 4-day cycling female rats. Mating behavior was essentially normal and occurred at times similar to sham-adrenalectomized animals on the afternoon of predicted proestrus. The number of ova ovulated was significantly reduced in mated adrenalectomized subjects in contrast to data reported by Rodgers (1971) for intact females mated at similar times in proestrus. Embryonic swellings were significantly fewer at day 10 of gestation than in the sham-adrenalectomized group providing additional evidence of reduced numbers of ova ovulated. Embryonic weights at day 10 of gestation were not affected by adrenalectomy. Removal of adrenocortical hormones significantly increased uterine weight on the morning of vaginal estrus. The data fail to show a significant delay in sexual receptivity as a result of removing adrenal progesterone, but suggest that adrenalectomy interferes with the neuroendocrine reflex mediating ovulation.     

松褐天牛的交配行为

采用室内试验和野外观察相结合的方法,对松材线虫病的主要媒介昆虫松褐天牛Monochamus alternatus Hope的交配行为进行了研究。结果表明： 松褐天牛一次完整的交配包括相遇抱对、插入输精和配后保护3个阶段,在交配过程中雄虫有多次插入输精现象发生。室内试验中共观察到松褐天牛的交配123次,松褐天牛一次完整的交配过程平均需时63.49 min,其中输精前的抱对时间平均为1.68 min,交配过程中每次输精插入时间平均为57.60 s,配后保护时间为15.18 min。松褐天牛在开始交配的4天内平均交配5.15次,不同雄性个体所获得的交配机会差异很大。松褐天牛的交配行为表现出强烈的雄性竞争现象,雄虫能根据雌虫或自身的交配经历调整交配投入,当雌虫或者雄虫是初次交配时,总输精时间和插入输精的次数显著大于与有交配经历的雌虫或雄虫交配时的输精时间和插入输精次数。田间松褐天牛的交配行为与室内观察结果基本一致。     

Sexual History Affects Mating Behavior and Mate Choice in the Crayfish Orconectes limosus

Because mating entails both costs and potential benefits to both sexes, males and females should be under selection to make optimal choices from among available potential mates. For example, in some cases, individuals may benefit by using information on potential mates' previous sexual histories to make mate choices. In such cases, the form and direction of these benefits may vary both between the sexes and based on the sexual history of the choosing individuals themselves. We investigated the effects of recent previous sexual history on the mate choice and mating behavior of both males and females of the crayfish Orconectes limosus. In one experiment, we found that opposite‐sex dyads comprising crayfish that had both mated 7–8 d previously with other conspecifics were significantly less likely to mate than dyads in which at least one crayfish was unmated. In a second experiment, we found that, when presented with a choice of tethered (but free to move) opposite‐sex conspecifics, only virgin females discriminated between males based on sexual history, showing a preference for virgin males over recently mated males. Mated females, mated males, and virgin males showed no preferences based on the sexual histories of potential mates. We discuss the implications of these inferences in the context of what was previously known about mating behavior and potential sperm limitation in crustaceans and other taxa.     

Functional significance of behavioral,morphological, and endocrine correlates across the ovarian cycle in semifree ranging female Tonkean macaques

The role of sexual displays in mating strategies and their reliability in indicating the time of ovulation has given rise to multiple explanations in nonhuman primates. In order to discriminate among hypotheses, socio-sexual behaviors were recorded in a semifree ranging group of Tonkean macaques (Macaca tonkeana), together with sexual skin swelling volumes and measurements of urinary concentrations of estrone conjugates and pregnanediol glucuronide. A clear preovulatory peak of urinary estrogen levels occurred 2 days before a defined rise in pregnanediol glucuronide concentrations, indicating that both hormones pointed out the female's ovulatory period. The concept of estrus rightly could be applied to female Tonkean macaques since fluctuations in estrogen levels correlated with cyclic changes in genital swelling sizes and rates of female behavioral attractivity and proceptivity. Males proved to be capable of recognizing the optimal conception period as judged from the occurrence of maximal rates of following behavior, serial matings, and ejaculations during the peri-ovulatory phase. During this time, males succeeded in maintaining exclusive and enduring associations with females. However, consortships occurred precociously, with males starting to affiliate with females, follow, and mount them 1 week before the presumed time of ovulation. These long-lasting consortships appear to be a consequence of the female extended follicular phase. This presumably sexually selected character allowed females to extend conspicuous sexual displays: genital swelling and utterance of an estrous call, which might attract males' attention and arouse them. With regard to female mating tactics, the combination of reliably indicating the time of ovulation to the male and durable periods of competitor exclusion led to reject explanations assuming manipulation about paternity or long-lasting intermale competition incitement in Tonkean macaques. Competition for mates between females also turned out to be an irrelevant factor as it was very low in the species. We conclude that the main function of sexual displays is to herald the approach of ovulation toward available mates. Am. J. Primatol. 46:285–309, 1998. © 1998 Wiley-Liss, Inc.     

Olfactory bulbectomy blocks mating-induced ovulation in musk shrews (Suncus murinus)

In many species, reproductive function can be modified by olfactory inputs. We employed bilateral olfactory bulbectomy (BULBX) to examine the effects of disruption of olfactory inputs on mating behavior and ovulation in female musk shrews. On several measures, sexual behavior was delayed in BULBX females compared to controls. When females were mated on five consecutive days, the majority of unoperated and sham-operated (SHAM) shrews ovulated; only one female subjected to BULBX ovulated. Administration of GnRH induced ovulation in the majority of females. We performed immunocytochemistry to assess the effects of bulbectomy on mating-induced responses of the neural GnRH system. In BULBX and SHAM females, the numbers of cells containing proGnRH immunoreactivity in the medial septum (MS)/diagonal band (DB) were significantly elevated 1 h after mating. Bulbectomy increased the numbers of GnRH-immunoreactive peptide-containing cells in the preoptic area, but it reduced neuron numbers in the MS/DB, as compared with those in SHAM controls. In addition, the GnRH-immunoreactive fiber area in the median eminence was greater in BULBX than in SHAM females. In sum, female musk shrews can display receptivity and engage in copulation without olfactory inputs. However, the olfactory system is essential for mating-induced ovulation.     

Theoretical influence of female mating status and remating propensity on male sperm allocation patterns

Theoretical models predict that males should allocate more sperm in matings where the immediate risk of sperm competition is high. It has therefore often been argued that males should invest less sperm in matings with virgin females compared with matings with already mated females. However, with relatively polyandrous females, high sperm competition risk will covary with high sperm competition intensity leading to more unpredictable conditions, as high competition intensity should favour smaller ejaculates. With the use of a genetic algorithm, we found that males should allocate more sperm in matings with virgin females when female mating frequency is relatively high, whereas low remating rates will select for higher effort in matings with nonvirgin females. At higher remating rates, first male sperm precedence favours larger ejaculates in matings with virgin females and second male precedence favours the reverse. These results shed some light on several findings that have been difficult to explain adaptively by the hitherto developed theory on sperm allocation.     

Influence of previous mating experience on future mating success in maleLucilia cuprina (Diptera: Calliphoridae)

Receptive and virginL. cuprina females were placed with a virgin male and an experienced male that had mated between one and five times previously. The experienced males secured significantly more matings than virgin males. Males with previous matings also gained experience in competing with males. Males directed mating attempts at each other, seemingly in the context of intrasexual competition. Experienced males directed more mating attempts at virgin males than vice versa. As their number of previous matings increased, experienced males made the first mating attempt at females more often and directed more mating attempts at females compared with virgin males. Females did not actively discriminate against experienced males, even though the proportion of matings secured on the first attempt by experienced males declined with increasing mating experience. Alternative behavioral explanations are discussed.     

Multiple matings increase the fecundity of the yellow swallowtail butterfly,Papilio xuthus L., in summer generations

Females of the yellow swallowtail butterfly, Papilio xuthus,were reared in the laboratory. They were divided into four groups held under different mating conditions: nonmating (virgin) and mated once, twice, and three times. The number of eggs in the ovaries was counted by dissection. Virgin females produced increasing numbers of mature eggs, up to about 30, in the week following emergence. When the female had mated once, the number of mature eggs was significantly higher than that of virgin females by the second day after emergence. However, the double- and triplemated females did not increase the number of eggs in each state further than the singlemated females. The double-mated females deposited significantly more eggs than the singlemated females in the laboratory. The triplemated females also deposited more eggs on the day after the third mating than the doublemated females. Thus, multiple matings increased the number of eggs deposited. The change in the hatchability and the morphology of the spermatophore in the bursa copulatrix suggested that the sperm from the last mating had precedence.     

Remating, sperm transfer, and sperm displacement in the cactophilic species Drosophila buzzatii Patterson & Wheeler (Diptera: Drosophilidae)

The mating system of Drosophila buzzatii is characterized by short copulation duration, frequent remating in both males and females, and male ejaculate partitioning. Additional features of the system are strong sperm displacement and a high frequency of sterile matings. Remating frequencies and the effects of remating on various mating parameters were studied. In order to characterize variation, five isofemale lines from geographically distant localities in Australia (three localities), Brazil and the Canary Islands were used. Mating parameters studied were: premating time, copulation duration, interval between successive matings, and progeny number as a measure of sperm transfer. Variation for sperm displacement was studied in crosses between laboratory stocks and a number of isofemale lines from Australia. There were significant between‐line differences in female remating frequencies, premating time, copulation duration, interval between successive matings, and progeny numbers, indicating genetic variation for these traits. Females from the five lines mated on average 1.6 to 3.1 times in 4 h, with a maximum of eight matings for one female. The males were given a maximum of ten virgin females in sequence and more than one‐third of the males mated all ten females in the 2 h observation period. Copulation duration decreased and interval between matings increased with copulation number in multiply mated males. Mean copulation duration was c. 2 min. Sperm transfer, measured as the average number of progeny from a single mating, was low (c. 25) and multiply mated females gave more progeny than single mated females, although with much lower progeny numbers than observed in wild‐caught non‐virgin females. A surprisingly high proportion of observed matings gave no progeny, i.e. they were sterile matings. Sperm displacement was strong in most crosses and remained strong in multiply mated females. The results are discussed in relation to the evolution of mating patterns in Drosophila.