Rhythmic egg-laying behaviour in virgin females of fruit flies Drosophila melanogaster

Fruit fly Drosophila melanogaster females display rhythmic egg-laying under 12:12?h light/dark (LD) cycles which persists with near 24?h periodicity under constant darkness (DD). We have shown previously that persistence of this rhythm does not require the neurons expressing pigment dispersing factor (PDF), thought to be the canonical circadian pacemakers, and proposed that it could be controlled by peripheral clocks or regulated/triggered by the act of mating. We assayed egg-laying behaviour of wild-type Canton S (CS) females under LD, DD and constant light (LL) conditions in three different physiological states; as virgins, as females allowed to mate with males for 1?day and as females allowed to mate for the entire duration of the assay. Here, we report the presence of a circadian rhythm in egg-laying in virgin D. melanogaster females. We also found that egg-laying behaviour of 70 and 90% females from all the three male presence/absence protocols follows circadian rhythmicity under DD and LL, with periods ranging between 18 and 30?h. The egg-laying rhythm of all virgin females synchronized to LD cycles with a peak occurring soon after lights-off. The rhythm in virgins was remarkably robust with maximum number of eggs deposited immediately after lights-off in contrast to mated females which show higher egg-laying during the day. These results suggest that the egg-laying rhythm of D. melanogaster is endogenously driven and is neither regulated nor triggered by the act of mating; instead, the presence of males results in reduction in entrainment to LD cycles.     

The effect of male mating history on paternal investment, fecundity and female remating in the seed beetle Callosobruchus maculatus

1. In many organisms, males provide nutrients to females via ejaculates that can influence female fecundity, longevity and mating behaviour. The effect of male mating history on male ejaculate size, female fecundity, female longevity and female remating behaviour in the seed beetle Callosobruchus maculatus was determined.
2. The quantity of ejaculate passed to females declined dramatically with successive matings. Despite the decline, a male's ability to fertilize a female fully did not appear to decline substantially until his fourth mating.
3. When females multiply mated with males of a particular mated status, the pattern of egg production was cyclic, with egg production increasing after mating. Females multiply mated to virgins had higher fecundity than females mated to non-virgins, and females mated to twice-mated males had disproportionately increased egg production late in their life.
4. Females that mated to multiple virgins, and consequently laid more eggs, experienced greater mortality than females mated only once or mated to non-virgins, suggesting that egg production is costly, and rather than ameliorating these costs, male ejaculates may increase them by allowing or stimulating females to lay more eggs.
5. Females mating with non-virgin males remated more readily than did females mated to virgins. Females given food supplements were less likely to remate than females that were nutritionally stressed, suggesting that females remate in part to obtain additional nutrients.     

A survival cost to mating in a polyandrous butterfly, Colias eurytheme

Adaptations that enhance fitness in one sex may be harmful to members of the opposite sex and lead to antagonistic coevolution between the sexes. In fruit flies, for example, selection for fertilization success has rendered the male ejaculate slightly toxic to females. Here we investigated whether mating imposes a cost upon female fitness in a polyandrous pierid butterfly ( Colias eurytheme ) by comparing life history traits between once-mated females and virgins. Mated females laid relatively more eggs early in their adult life, but suffered a reduction in longevity relative to virgins held under identical experimental conditions. The effect of mating on female survivorship was statistically independent of lifetime and early life fecundity. Moreover, lifetime fecundity co-varied positively with longevity across all females, and across females within each treatment group, hence there was no phenotypic trade-off between survival and reproduction. These results suggest that the observed longevity difference between virgin and mated females represents a true cost of mating, possibly arising from a toxic side effect of the male ejaculate. However, irrespective of this cost, virgin and mated females laid an equivalent lifetime number of eggs. Female C. eurytheme are also known to use nutrients from the male ejaculate to supplement their reproductive output, hence it is presently unclear how the observed longevity cost may have influenced the evolution of lifetime mating schedules in this polyandrous species.     

Influence of mating on ovarian follicle development in Triatoma infestans (Klug, 1834).

This work examines the influence of mating on ovarian follicle development in Triatoma infestans. The observations were carried out on both virgin and mated females, which were killed at various times after their emergence. There was no difference in the ovarian development of both experimental groups during the first gonadotrophic cycle. By the 7th day mated females as well as virgin females showed vitellogenic oocytes. The coriogenesis and ovulation process began on the 13th day after imaginal moulting. However we could observe that egg-laying was dependent on mating. Mated females laid eggs whereas virgin females did not lay eggs. However ovarian production was significantly greater in the mated females. It is suggested that in T. infestans mating stimulates egg-laying but it does no influence the oogenesis and ovulation process.     

Stimulation of virginal oviposition by male factor and its effect on spontaneous nervous activity in Bombyx mori

The injection of an extract of whole male reproductive tracts in water or Ringer's solution into virgin moths resulted in stimulation of egg-laying. The injection of an extract of the male abdomen without the reproductive tract, alimentary canal and Malpighian tubules dissolved in Ringer's solution into virgins had a slight effect on egg-laying. Furthermore, the addition of the extract of male reproductive tracts to preparations which were used to record spontaneous discharges of motor neurones in the last abdominal ganglion (SMG IX) of virgin moths brought about an excitation of the activity of the ganglion. Consequently, it is concluded that there exists in the male reproductive tract an oviposition stimulating substance (OSS) which could be transferred during mating. It is also postulated that the OSS can pass through the walls of the female internal genitalia into the haemocoel, and that this substance can affect the activity of SMG IX and, therefore, the process of egg-laying.     

Oviposition in Triatoma protracta: Role of mating and relationship to egg growth

Yolk deposition begins in the terminal oocytes of virgins of Triatoma protracta a few days after adult eclosion, and while a few eggs may be matured before vitellogenesis ceases, none are laid. Mating at day four stimulates egg maturation and oviposition in fed and unfed females, egg-laying beginning as early as nine days after eclosion. If mating is delayed until day 16, by which time vitellogenesis normally has ceased, stored eggs are laid within two to four days and yolk deposition is resumed. Removal of the brain prevents oviposition, as does the severance of the ventral nerve cord. Thus, an intact central nervous system is required for egg-laying. Also, since neither operation inhibits egg maturation or ovulation, it appears that the latter reproductive responses to mating are independent of oviposition.     

Quantitative aspects of the effect of mating on readiness to lay in the Australian sheep blowfly,Lucilia cuprina

Virgin females of Lucilia cuprinararely lay eggs, whereas mated females do so readily. This effect of mating is due entirely to increased readiness to lay, and not to any effect on ovarian development. An investigation was made of how readiness to lay was affected by matings which differed in terms of the male's chemical and mechanical contribution. Individual males were mated, during 1 day, to a succession of females whose readiness to lay was determined 1 or 8 days after mating. On both days, the proportion of females laying was inversely related to the number of females with which the male had previously mated. A high proportion of females that had mated with previously unmated or oncemated males laid at both 1 and 8 days after mating. However, this proportion tended to decline between day 1 and day 8 in females that had mated with males with two or more previous matings, and this effect was most evident in females mated with males that had previously mated with four or more females. When matings were manually terminated as soon as coupling had occurred, the proportion laying remained as low as in virgins. This proportion progressively increased as mating duration increased from 2 to 6 min. The proportion that laid after mating terminated at 6 or 8 min was as high as that for females from full-term matings (mean duration, 12.5 min). The results are generally similar to those obtained in parallel experiments on the effect of mating on sexual receptivity in this species and, therefore, indicate that the physiological bases for the two effects of mating might be the same.     

Lifetime ovipositional patterns of mated and virgin onion flies,Delia antiqua (Diptera: Anthomyiidae)

Over their 47.2±1.9 (mean±SEM) day lifespan, mated onion flies, Delia antiqua, oviposited more uniformly than did virgins. Mated females began ovipositing at 6.4±0.2 days old and regularly deposited 14.2±0.6 eggs/day for 3-4 weeks. Thereafter, oviposition slowed and stopped at about 1 week before death. Virgin flies began ovipositing 24.7±1.5 days into their 59.0±3.8 day lifespan, and deposited eggs at an increasing rate for 3-4 weeks, generating a mean overall ovipositional rate of 5.8±0.5 eggs/day. The later onset of virgin oviposition (ovipositional activation) and not a shorter ovipositional period largely accounted for the disparity between virgin and mated female lifespans. Mean lifetime egg production of mated females was 475±27 eggs versus 179±30 eggs for virgins. Ovipositional and post-ovipositional periods (34.4±1.8 and 7.2±1.0 days) for mated females were not significantly different from those of virgin females (30.9±3.6 and 6.7±1.2 days). Over 90% of virgin females laid eggs. The distinction between mated and virgin ovipositional patterns may be specifically attributed to differences in: (1) egg maturation, (2) age at ovipositional activation, and (3) egg-laying rate.     

Combinative stimulation inactivates sex pheromone production in the silkworm moth, Bombyx mori.

Mating results in a strong suppression of sex pheromone (bombykol) production in the female silkworm moth, Bombyx mori. The mechanical stimulation from the insertion of a penis, inflation of the bursa copulatrix (BC), or copulation with the sterile male whose penis was removed in order to prevent ejaculation (pr-male) induced only a partial decline in bombykol production. Artificial insemination stimulates oviposition of fertilized eggs as does normal mating. However, bombykol production did not decline in artificially inseminated females. When females were artificially inseminated before or after mating with pr-males, some females had a small amount of bombykol, similar to females mated with normal males, while other females had a large amount of bombykol similar to virgin females. The former usually laid fertilized eggs, while the latter laid only unfertilized eggs though semen filled their spermatophores and spermathecae. The mechanical stimulation caused by mating with a pr-male could be replaced by covering the abdominal tip with melted paraffin. Neither implantation of the BC obtained from mated females, nor injection of the spermatophore extract, into a female mated with a pr-male could inactivate bombykol production. Injection of hemolymph from a mated female into a virgin also failed to affect bombykol production These results indicate that a combination of both the tactile stimulation of the abdominal tip and the arrival of fertile spermatozoa in the vestibulum trigger a neural inactivation mechanism of bombykol production after mating.     

Post‐mating enhancement of fecundity in female Lygus hesperus

Although mated females of the western tarnished plant bug Lygus hesperus Knight are known to produce more eggs than virgins, the nature of the inducing stimuli and the specific changes occurring in the female require additional elucidation. Compared with virgin females isolated from males, those exposed to male precopulatory behaviours produce similar numbers of eggs, whereas inseminated females produce 50% more during the observation period. Although the quantity of seminal fluids received by a female does not influence egg number, mating twice within a 10‐day span causes a 16% increase in fecundity, on average. Females mating more than twice during the same period do not exhibit additional increases in egg number. Because virgin females contain more chorionated eggs than are laid, mating appears to enhance the rate of oviposition. However, to achieve a sustained increase in fecundity, an augmented rate of oocyte maturation would also be required. Male‐derived spermatophores lack substantive quantities of nutrients that might otherwise have enhanced female fecundity. The total amounts of carbohydrate, protein and lipid, as well as eight essential minerals transferred by the male, are insufficient for producing even a single egg, and the female has already produced a large number of chorionated oocytes before she mates. Collectively, the data suggest that seminal fluid contains one or more activational molecules, such as a peptide, which triggers an increase in egg deposition. A prolonged increase in oviposition rate may be achieved through multiple matings to ensure a supply of sperm or to offset the degradation of the putative activational factor.     

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.     

Effects of multiple mating and male eye span on female reproductive output in the stalk-eyed fly, Cyrtodiopsis dalmanni

Females of the stalk-eyed fly, Cyrtodiopsis dalmanni, mate repeatedly during their lifetime and exhibit mating preferencefor males with large eye span. How these mating decisions affectfemale fitness is not fully understood. In this study, we examinedthe effects of multiple mating and male eye span on short-termreproductive output in this species. Experiments that manipulatedthe number of copulations and partners a female received suggested that obtaining a sufficient sperm supply is an important benefitassociated with multiple mating. The average percentage offertile eggs laid by females increased as a function of matingfrequency and ranged from 40% for females mated once, to 80%for females mated continuously. In addition, a high proportionof copulations in this species appeared to be unsuccessful. One-third of all females mated once laid less than 10% fertileeggs. There was no significant difference in reproductive performancebetween females mated to multiple partners and females matedto a single partner. There was also no indication that femalesreceived any short-term reproductive benefits from mating withmales with large eye span. In fact, females mated to males with short eye span laid a higher percentage of fertile eggs thanfemales mated to large eye span males.     

Male age and sexual experience affect male mating behavior in the hawthorn spider mite,Amphitetranychus viennensis

As is reported, in species with first-male sperm precedence, male age and previous sexual experience play crucial roles in male mating behavior. In the hawthorn spider mite, Amphitetranychus viennensis Zacher, previous studies showed that only females that copulated for the first time could achieve fertilization. Based on this, the effects of male age and mating history on male mate choice and male mate competition were investigated. It was confirmed that males could distinguish virgins from fertilized females but they were unable to discriminate between virgins and unfertilized females. Interestingly, the copulation duration of males mated with fertilized females was much shorter than that of males mated with virgins or unfertilized females. Additionally, for male mating choice, males of all ages and more experienced males preferred 5-day-old virgin females, whereas only less experienced males preferred 1-day-old virgin females. In male-male competition, 3-day-old males were more competitive and obtained more copulations compared with others. Copula duration was closely related to male age. Though no significant differences were observed in mating competition between virgin and mated males, copula duration of males in first copulation was the longest and gradually shortened in subsequent copulations. In all, this investigation demonstrated that male age and sexual experience affected male mate choice and male-male competition, leading to further insight into the influences of male age and sexual experience on the reproductive fitness of both sexes.

     

Female Gryllus vocalis Field Crickets Gain Diminishing Returns from Increasing Numbers of Matings

Although female insects generally gain reproductive benefits from mating frequently, females do not mate unlimited numbers of times. This study asks whether the limit on female mating rate is imposed by trade‐offs between reproduction and survival. Female Gryllus vocalis were given the opportunity to mate 5, 10, or 15 times with novel males, and the effects on daily fecundity (egg production), fertility (proportion of eggs that were fertilized), and female post‐experimental longevity were measured. Females that mated 10 times laid more eggs and had a higher proportion of fertile eggs than females that mated 5 times. However, females that mated 15 times did not lay significantly more eggs or have a higher proportion of fertile eggs than females that mated 10 times. Although number of matings did not affect the date that females laid their last egg, mating more times was associated with a prolonged period of laying fertile eggs. Number of matings did not affect female post‐experimental longevity. Thus, there was no trade‐off between female reproductive effort and survival, even when females mated very large numbers of times. When females were allowed to mate ad libitum, the average number of times that females mated was greater than the number of times that confers maximal fitness. The lack of cost to mating explains why females might be willing to mate beyond the point of diminishing reproductive returns.     

The relationship between mating and oogenesis in monarch butterflies (Lepidoptera: Danainae)

We studied the relationship between the timing of mating and oogenesis in monarch butterflies (Danaus plexippus) to determine (1) the potential for male nutrient input into eggs and (2) whether mating stimulates egg development. Most females mated soon after they started maturing eggs. One and 2 days after mating, females contained the same number of mature oocytes as virgin females of the same age, while 3 days after mating they contained more mature oocytes than did virgins. These results confirm the potential for male-derived nutrients to augment oocyte production, but indicate that mating is not required for oocyte maturation to occur.     

广聚萤叶甲成虫交配时长对产卵量与孵化率的影响

【目的】明确不同交配时长对广聚萤叶甲雌虫产卵量和卵的孵化率的影响。【方法】在室内条件下,对不同交配时长下广聚萤叶甲的雌虫产卵量和卵的孵化率进行观察:(1)选取羽化第3d的广聚萤叶甲雌雄虫随机配对,观察24 h,记录交配情况和时长;(2)在交配开始1、5、15、30、60 min时,强行分开雌雄成虫,然后将不同交配时长的雌虫进行单独饲养,以正常交配一次的雌虫作为对照,每个处理选取23组;(3)将15～30 cm健壮豚草小苗插入注满水的塑料小瓶内,将配对的一组雌雄成虫和豚草小苗放入养虫盒中饲养,每天更换带卵的小苗并记录叶片上的产卵量;(4)将上述带卵的小苗至于适宜条件下培养,记录5～7 d内卵块孵化的情况。【结果】广聚萤叶甲正常交配一次的对照组的产卵水平显著高于各处理组,单雌产卵为889粒,交配时间15 min以下各组雌虫的产卵量明显低于交配30 min以上的各组雌虫。同时交配时长5 min以下雌虫产的卵基本不能孵化,而交配时间达到30 min以上的各组卵块的孵化率明显提高。【结论】雄虫转移雌虫受精所需精子量需要耗费的时间为30 min左右,且雄虫有延长交配时间的趋性。该结果为研究广聚萤叶甲的生态特性以及优化种群繁殖提供科学依据。     

Factors affecting female sexual receptivity in the planthopper, Prokelisia dolus

Abstract. The mating system of Prokelisia dolus Wilson (Homoptera: Delphacidae) was characterized by determining: if males and females multiply mate; when transitions occur in female sexual receptivity, what triggers sexual refractoriness; and what behaviours characterize unreceptive virgins, receptive virgins, and unreceptive mated females. Males copulated with up to six females in less than 1 h, but completely inseminate, on average, only the first four females. Females rarely mated more than once, unless males were depleted of sperm due to previous copulations or if copulation was interrupted (if duration was<2 min). Male and female calling was associated (100% and 91%, respectively) with sexual receptivity and resultant matings. The transition from unreceptive virgin to receptive (calling) mature virgin occurred 48 h posteclosion, and all were mated by day 4. Females that were sexually immature and those completely inseminated did not call. Rejection of males by females included walking away from approaching males (65%), female kicking (7%), and abdominal lifting (5%). Rejection of males was observed by immature, mature and calling, and mated females. Sexual refractoriness was not triggered by acoustic and visual stimuli or mechanical stimulation of genitalia. Refractoriness was also not triggered by reception of small quantities of sperm because some females laid a few viable eggs yet calling was not terminated. Sexual refractoriness was activated by a substance in the ejaculate as demonstrated by injection into the haemocoel of male accessory glands or testes and homogenates of seminal vesicles. This is the first study that documents the role of male ejaculate in inhibiting female sexual receptivity in Hemiptera (Homoptera).     

Factors influencing the onset of egglaying in a cecidomyiid fly

Abstract The timing of the onset of egglaying in the Hessian fly, Mayetiola destructor (Say), is influenced by several exogenous and endogenous factors. Mated females initiated egglaying 48 h earlier than virgins and laid 3–4 times more eggs before dying. The effects of mating on the onset of egglaying were further modified by several other factors whose effects were measured in hours rather than days. Increases in ambient temperatures experienced by mated females shortened the post-mating pre-ovipositional transition phase; however, the effects of temperature were not linear throughout the temperature range. Age of females at the time of mating also influenced the onset of egglaying. Females that mated 1 , 2 and 3 h after eclosion spent 190 , 160 and 120 min in the post-mating transition phase, respectively. Effects of age were also observed when females were mated over the three calling periods that comprise the 3-day lifespan of the adult female. Linear regressions of transition times on time of mating had similar slopes for first and second day post-eclosion females but were offset such that first-day females mated late in the morning had similar transition times to second-day females mated early in the morning. By the third day post-eclosion, transition times showed no significant changes when females were mated throughout the calling period. Possible mechanisms underlying the effects of mating, temperature, and female age on post-mating pre-oviposition transition times are discussed.     

Rhythmicity of mating and oviposition inCallosobruchus subinnotatus (Pic) (Coleoptera: Bruchidae)

Mating and oviposition behaviors were studied inCallosobruchus subinnotatus. Copulation was most frequent during the late scotophase, 2–3 h before onset of photophase. The females were less willing to mate during photophase, which increased the time to initiate mating while decreasing the duration of mating. Females exhibited increased movement prior to mating, resting immediately after mating, and remained stationary for 6 h when oviposition commenced. Multiple mating by both males and females affected the number of eggs laid, duration of mating, and uncoupling time at the end of mating. Females that mated two or three times laid more eggs than females that mated once or more than three times. Females that remainedin copula for less than 18 min showed greater readiness to remate than those that remainedin copula longer. There was a gradual decrease in the number of eggs females could lay with an increase in the number of previous matings by males.     

Behavior of triatomines (Hemiptera:Reduviidae) vectors of Chagas' disease. IV. Fecundity, fertility and longevity of Panstrongylus megistus (Burm., 1835) pairs and virgin females starved under laboratory conditions

A laboratory study was conducted on the fecundity, fertility and life span of Panstrongylus megistus pairs and on the fecundity and life span of P. megistus virgin females submitted to starvation after the last moulting. Of the mated females, 22.2% laid eggs, 4.4% of which were fertile. Females resisted starvation more than males. Of the starved virgin females, only 10% laid eggs, with a low egg-laying rate (0.47) per female. Resistance to starvation was lower in virgin than in mated females.