Mating behavior of the cabbage beetle, Colaphellus bowringi (Coleoptera: Chrysomelidae)

Abstract  Circadian mating rhythms, mating frequency, mating duration, and the effect of mating duration on fecundity and fertility in the cabbage beetle, Colaphellus bowringi were investigated in the laboratory. Mating occurred throughout the 24-h cycle but the majority of copulations occurred in the photophase with two apparent peaks, one at 8:00 and another at 16:00. Mating frequency observations for 10 consecutive days indicated that pre-mating period of C. bowringi was about 4 days, and pairs mated an average of 5 times per day and an average of 40 times during the first 10 days. There was a negative correlation between mating frequency and mating duration during the consecutive mating. The mean duration of the first copulation (136.24 ± 4.62 min) was significantly longer than those of the second (57.87 ± 2.03 min), third (53.05 ± 2.05 min) and fourth copulation (30.86 ± 2.98 min). Fecundity showed a slight increase with increasing mating duration but no significant difference among treatments. However, fertility was significantly influenced by the mating duration in this species. Mating of 20-min duration did not produce viable eggs. The mean percentage of fertile eggs with completed mating duration (204.43 ± 18.96 min, 56.75% fertile eggs) was significantly higher than those with 60 min (39.55%) and 30 min (17.91%) mating duration, suggesting that the longer mating duration might be associated with transfer of more sperm that are used to increase the fertility of eggs.     

Effect of male and female multiple mating on the fecundity, fertility, and longevity of diamondback moth, Plutella xylostella (L.)

Abstract:  The effect of diamondback moth (DBM), Plutella xylostella (Lep., Plutellidae) male and female multiple mating on fecundity, fertility, and longevity was studied. Males could mate for five times with virgin females during scotophase. The successful copulation rates, fecundity of female, and longevity of both females and males decreased when male mating times increased, whereas copulation duration increased. Correlation coefficient between copulation duration and male mating times was significant ( r  = 0.7358, P = 0.0001, spearman rank-order correlation). There were linear relationships between mating history of males and longevities of males and females, and regression relationships between them were significant. Mated females had similar daily reproductive pattern, which laid the most eggs on the first day after mating in spite of their mates' mating history. Virgin females laid some infertile eggs before they died. Most of the females mated once during their lifespan but 19.9% of females mated twice when one female kept with one male during scotophase. There were no significant differences in the fecundity, fertility and longevity between the single- and twice-mated females. Correlation coefficient between copulation duration and female mating times was not significant ( r  = 0.0860, P = 0.8575). Results suggested that DBM females may be monandrous. Multiple mating did not increase male or female mating fitness.     

Optimal number of matings in two aphidophagous ladybirds

Abstract.  1. The present study was designed to identify the optimal number of matings required for maximum fecundity and egg viability in two aphidophagous ladybirds, Cheilomenes sexmaculata and Propylea dissecta .
2. For this purpose, ladybirds were subjected to different numbers of matings and the reproductive responses were recorded thereafter.
3. The Gompertz model was used to draw asymptotic graphs for fecundity and per cent egg viability in both ladybird species. Ninety-five per cent and 50% of maximum theoretical fecundity and per cent egg viability were predicted from the model.
4. Ninety-five per cent maximum theoretical fecundity was obtained after 13.25 and 12.95 matings in C. sexmaculata and P. dissecta , respectively; and 8.95 and 11.25 matings were required for 95% maximum theoretical per cent egg viability in C. sexmaculata and P. dissecta , respectively.
5. The results of these experiments clearly support the existence of an optimal number of matings in these two ladybird species leading to maximum adult fitness.     

Age-specific mating and reproductive senescence in the seven-spotted ladybird, Coccinella septempunctata

Abstract:  Adults of the seven-spotted ladybird, Coccinella septempunctata Linnaeus (Col., Coccinellidae) were paired for mating from very young to old age (1–50 days) to record the willingness to mate, attainment of sexual maturity and onset of reproductive senescence in both the sexes. Mating commenced after 4 and 2 days of emergence of male and female, respectively, and 100% mating was achieved at the young age in both cases (10 days). Willingness to mate decreased with increase in the age from 40 to 50 days of both the sexes. Ladybird exhibited protandry. Mating duration, fecundity and per cent viability of eggs of middle-aged males (20–30 days old) and females (20 days old) were the highest. Mating duration and per cent viability of eggs were male age dependent, whereas pre-oviposition and oviposition periods were mating stimulus dependent. Oviposition period and fecundity were female age-dependent responses. Fecundity was highest when 20-day-old female and 30-day-old male were paired. Onset of reproductive senescence started at the age of 30 days in males and 20 days in females. The present study confirms the effect of ageing on male and female C. septempunctata and supports the Hansen and Price [J. Evol. Biol. (1995) vol. 8, pp. 759–778] model that females mating with young and middle-aged males yield optimal quality progeny.     

Mating in aphidophagous ladybirds: costs and benefits

Abstract:  Mating costs and benefits were studied in three aphidophagous ladybirds, viz. Cheilomenes sexmaculata , Coccinella septempunctata and Propylea dissecta by subjecting them to different numbers of matings. Longevity, fecundity and percent egg viability were regressed with number of matings to determine the costs and trade-offs, if any. Longevity decreased with increasing number of matings in both C. sexmaculata and P. dissecta indicating a cost of mating. The lack of such a cost in C. septempunctata has been ascribed to spermatophore consumption by females of this ladybird. Both fecundity and percent egg viability increased with increasing number of matings and are probably indicative of the benefits. Short-lived females distributed their reproduction uniformly in their lifetime while long-lived females showed a high burst of reproductive activity followed by a gradual decline. Percent egg viability decreased after the completion of the requisite number of matings.     

Intrinsic advantages of Cheilomenes sexmaculata over two coexisting Coccinella species （Coleoptera：Coccinellidae）

Development, survival and reproductive performance of coexisting ladybird species, viz. Cheilomenes sexmaculata, Coccinella septempunctata, and Coccinella transversalis, of the tribe Coccinellini were studied and compared to assess their coexistence and ecological relationships. High values of life history parameters, viz. developmental rate,immature survival, fecundity, egg viability, reproductive rate and conversion of efficiency of ingested food were recorded for C. sexmaculata followed by C. transversalis and C.septempunctata suggesting that the former has intrinsic advantages over the latter two species. This could possibly counterbalance its disadvantages, like relatively smaller size and weight, thereby making it competitive. The developmental period increased with increase in body size. Exceptionally high fecundity after single mating has been recorded in C. sexmaculata. The egg viability, however, was lower than in both Coccinella species.     

Fecundity and fertility of ladybird beetle Harmonia axyridis after prolonged cold storage

Some species of ladybird beetles (Coleoptera: Coccinellidae) mate both before and after overwintering. The purpose of the pre-diapause mating was studied in the alien invasive ladybird Harmonia axyridis (Pallas 1773). Our study demonstrates the persistence of high fecundity (daily oviposition rate of 21 eggs per fertilized female during the first month of reproduction) and fertility (85 % of eggs hatching) of females of H. axyridis after long storage (up to eight months) at low temperature (6 °C). The females were not mated after activation in spring and had to rely on the sperm supply maintained from the pre-winter period (58 % of females were fertilized). Unfertilized females also laid eggs but in low numbers (an average of 345 eggs by virgin females during an individual’s lifetime, 1,174 eggs by females fertilized before winter) and after a longer pre-oviposition period (2–5 weeks in comparison to 7–8 days for fertilized females). We show that the unfertilised eggs were not trophic eggs. The high sperm survival ability observed questions the need for the high levels of sexual activity generally observed in Coccinellidae. Fertilized females of H. axyridis may found large colonies after dispersal to new areas even without males, which contributes to the striking invasive ability of this species.     

Effects of repeated mating and polyandry on the fecundity, fertility and maternal behaviour of female earwigs,Euborellia plebeja

I examined multiple mating and its function in female earwigs, Euborellia plebeja (Dermaptera: Anisolabididae). Like other earwigs, females of this species care for their eggs and intermittently lay eggs in clutches (iteroparity). Analysis of two polymorphic allozyme loci revealed that wild-caught adult females laid clutches with low within-brood genetic relatedness (0.210), indicating that females were promiscuous under natural conditions. Rearing experiments in the laboratory revealed that: (1) repeated mating with a single male increased female fecundity (number of clutches laid) and hence the number of hatchlings produced; (2) estimated sperm number was positively correlated with hatchability; (3) when frequency of mating was controlled, polyandry enhanced hatchability, although this effect was not statistically significant; (4) duration of maternal care varied for clutches with low hatchability, and sometimes exceeded the mean interclutch interval. Thus, although a possible benefit of polyandry is suggested, the greater beneficial effect of repeated mating on female fecundity can explain polyandrous mating in this species. Because female earwigs invest considerable effort in brooding their clutches, it may be adaptive to suppress oviposition unless stored sperm ensures high fertility. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.      

Sperm Quantity Explains Age-Related Variation in Fertilization Success in the Hide Beetle

Age-related variation in sperm quality and quantity may have a dramatic impact on female fecundity and fertilization success. Despite this, the relationships between these parameters are rarely investigated. Moreover, studies exploring age-related variation in male mating success generally fail to consider the entire lifespan of an individual male; instead they restrict analyses to a small number of defined age classes. As a consequence they are unable to assess the impact of early and late life history components on male reproductive success. In this study, we explore these questions using the hide beetle, Dermestes maculatus , a model species for investigating age-related male mating success. We first employed a longitudinal design to explore whether patterns of sperm transfer and subsequent reproductive success varied over the reproductive lives of a cohort of males. Secondly, we investigated age-related variation in sperm viability, a surrogate measure of sperm quality. Finally, we combined these data and assessed whether the observed patterns of sperm transfer were correlated with fertilization success. We found that the quantity of sperm varied with male age: the amount of sperm transferred to a female increased with male age until 9 wk and then started to decline. Similarly, female fecundity and fertilization success were related to male age: females mating with males when they were relatively young (1 wk) or relatively old (13 wk) suffered reductions in fecundity and fertilization. Our data suggest that fertilization success is driven at least in part by the quantity of sperm transferred during mating.     

Sperm transfer during mating, movement of sperm in the female reproductive tract, and sperm precedence in the common cutworm Spodoptera litura

Abstract. Mating behaviour, sperm transfer and sperm precedence were studied in the moth Spodoptera litura (Fabr.) (Lepidoptera: Noctuidae). There existed a rhythmic, diel pattern of mating behaviour of this moth during the scotophase, presumably set with respect to an endogenous activity rhythm. Approximately 30 min after copulation had started, the formation of the corpus of the spermatophore began in the bursa copulatrix of the female moth, but full inflation of the corpus was not completed until 45–60 min after mating had started. The mature spermatophore contained about 350 eupyrene sperm bundles and a large number of individual (loose) apyrene spermatozoa. The mating status and the age of the male insect influenced the number of sperm transferred to the female within the spermatophore, and also affected the consequent fertility. There was no evidence of sperm reflux within the male tract. Within the female, dissociation of eupyrene sperm bundles was evident within the spermatophore less than 15 min after the completion of mating. Spermatozoa began to move from the bursa (in which the spermatophore is lodged) into the spermatheca 30–45 min after the end of the copulation, and the quantity of sperm in the spermatheca reached a plateau at 90 min after mating. Apyrene sperm reached the spermatheca first, followed by eupyrene sperm. Examination of total (apyrene plus eupyrene) sperm in the female tract showed that 86% of mated females received an apparently normal amount of total sperm from the male. Examination of eupyrene sperm alone showed that 81% of matings resulted in an apparently normal transfer of eupyrene sperm. A small proportion (approximately 8%) of the matings, however, were identified as transferring a clearly subnormal quantity of eupyrene sperm to the spermatheca. The eggs produced as a result of such pairings displayed much reduced fertility (about 43%) compared to those from matings confirmed to have transferred normal quantities of sperm, which showed about 92% fertility. This shows that the availability of eupyrene sperm in the spermatheca may be an important constraint on fertility in normal populations of insects. In the laboratory, S. litura females exhibited multiple matings. Of the females, 93% mated, and the mean frequency of mating was 1.69. Mating with a fertile male led to the oviposition of an increased number of eggs. This effect continued even when the female subsequently mated with an infertile male. Displacement of sperm from previous matings is known to be an important factor in the evolution of multiple mating strategies. Our results on sperm utilization by S. litura indicated that after a second mating, the sperm utilized for subsequent fertilization were almost exclusively from the last mating with little mixing. The proportion of eggs fertilized by sperm from the second mating (P₂) was calculated as 0.95, indicating almost complete sperm precedence from the last mating.     

Female alpine newts (Triturus alpestris) mate initially with males signalling fertility benefits

Gametic asymmetry implies that females invest more per gamete than males do and thus sperm is considered to be a relatively cheap resource. However, contrary to this classic view, sperm has been shown to be frequently in short supply; hence, selection favouring females that mate for fertility benefits should occur. For this reason, we determined whether males signalling fertility are preferred by female newts of the species Triturus alpestris . We performed paired female–male trials using unmated and previously inseminated females to determine potential criteria for female interest in a courting male, to establish what factors lead to successful mating and to assess the importance of female choice for direct and indirect benefits. We found that female interest in any potential mate and mating success decreased once mating had occurred. Furthermore, we detected an increase in spermatophore deposition rate and rapid spermatophore transfer in encounters that resulted in a successful mating. The results obtained indicate that female alpine newts are attracted to males showing signs of relatively high fertility and that females exhibit a decreased propensity to mate once initial sperm reserves have been acquired. Our results support the theory of initial female choice for fertility benefits.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 483–491.     

FEMALES RECEIVE A LIFE-SPAN BENEFIT FROM MALE EJACULATES IN A FIELD CRICKET

Abstract.— Mating has been found to be costly for females of some species because of toxic products that males transfer to females in their seminal fluid. Such mating costs seem paradoxical, particularly for species in which females mate more frequently than is necessary to fertilize their eggs. Indeed, some studies suggest that females may benefit from mating more frequently. The effect of male ejaculates on female life span and lifetime fecundity was experimentally tested in the variable field cricket, Gryllus lineaticeps. In field crickets, females will mate repeatedly with a given male and mate with multiple males. Females that were experimentally mated either repeatedly or multiply lived more than 32% longer than singly mated females. In addition, multiply mated females produced 98% more eggs than singly mated females. Because females received only sperm and seminal fluid from males in the experimental matings, these life‐span and fecundity benefits may result from beneficial seminal fluid products that males transfer to females during mating. Mating benefits rather than mating costs may be common in many animals, particularly in species where female mate choice has a larger effect on male reproductive success than does the outcome of sperm competition.     

Sperm Numbers and Female Fertility in the Moth Plodia interpunctella (Hübner) (Lepidoptera; Pyralidae)

I investigated two possible reasons for remating in female Plodia interpunctella: i) females remate to obtain sufficient sperm to maintain fertility; and ii) male investment in non-sperm components increases female fecundity and longevity. The number of sperm and the mass of the spermatophore transferred by males decreases on successive matings. Sperm numbers and potential male investment were varied by allowing females to mate either once or twice with males either on their first or second mating. Females receiving a single small spermatophore containing few sperm (from a male on his second mating) had sufficient sperm to fertilize all their eggs. Females did not show increased fecundity or longevity as a result of obtaining more spermatophore material. I discuss why females remate when they already have sufficient sperm to fertilize all their eggs.     

Copulation, the dynamics of sperm transfer and female refractoriness in the leafhopper Balclutha incisa (Hemiptera: Cicadellidae: Deltocephalinae)

Abstract.  Mature sperm of the leafhopper Balclutha incisa (Matsumara) (Cicadellidae: Auchenorrhyncha: Hemiptera) are stored as a series of sperm bundles within seminal vesicles prior to ejaculation. During transfer, sperm are pumped from the vesicles into the ejaculatory duct to the complex aedeagus. Sperm transfer is marked by a c . 30-fold expansion of the spermatheca to accommodate both sperm and seminal fluid. Sperm number increases exponentially with male age, reaching a maximum of 700 000 after 14 days, while the number of sperm available on days 2–5 is between 70 000 and 100 000. During mating, maximum sperm transfer occurs after 7 min and mating is complete after about 10 min. Ejaculate size, defined by both sperm and associated accessory gland fluid, is influenced by male mating status and the interval since the previous mating. There is a positive correlation between duration of copulation and both ejaculate and the time to subsequent mating. Sperm are more likely to be retained in the testes during mating by males of 2–5 days post-emergence than older males. The number of sperm received by the female can be manipulated experimentally by mating males once (medium ejaculate) or twice (small ejaculate) immediately after their first mating. Females that receive small ejaculates from sperm-depleted males have a far shorter refractory period than females receiving medium to large ejaculates. Both ejaculate size and the time after males have mated influence the female post-mating refractory period as measured by the female's responsiveness to male sexual signalling.     

Effects of delayed mating on reproductive output of female oriental beetle Anomala orientalis (Coleoptera: Scarabaeidae)

1 Although management of the oriental beetle Anomala orientalis (Waterhouse) by mating disruption shows promise across a range of agricultural systems, relatively little is known about aspects of the reproductive biology of this species relevant to its management. We studied the effects of delayed mating on several aspects of the oviposition behaviour and biology of the oriental beetle using females mated in the laboratory at 4–13 days posteclosion. 2 Females exhibited a gradual decline in fecundity with increased age at mating that was largely a function of a decline in duration of the oviposition period, as well as lower female fertility: females mated at 11 days were less likely to lay any fertile eggs. However, egg fertility did not vary with female age at mating. 3 Because mating delay did not affect longevity, females mated at older ages experienced decreased oviposition periods; however, females laid more eggs per day with increased age at mating, which partially offset shorter oviposition periods. 4 A mating delay of ≥ 6 days relative to females mated within the first day of reaching sexual maturity resulted in an approximately 35–50% lower mean fecundity. 5 These results suggest that, for mating disruption to be a successful management tool for the oriental beetle, mating must be prevented rather than delayed. We compare the findings of the present study with the published research on delayed mating in moths and discuss the importance of these results in relation to management of the oriental beetle using female sex pheromones.     

Variation in the benefits of multiple mating on female fertility in wild stalk‐eyed flies

Polyandry, female mating with multiple males, is widespread across many taxa and almost ubiquitous in insects. This conflicts with the traditional idea that females are constrained by their comparatively large investment in each offspring, and so should only need to mate once or a few times. Females may need to mate multiply to gain sufficient sperm supplies to maintain their fertility, especially in species in which male promiscuity results in division of their ejaculate among many females. Here, we take a novel approach, utilizing wild‐caught individuals to explore how natural variation among females and males influences fertility gains for females. We studied this in the Malaysian stalk‐eyed fly species Teleopsis dalmanni. After an additional mating, females benefit from greatly increased fertility (proportion fertile eggs). Gains from multiple mating are not uniform across females; they are greatest when females have high fecundity or low fertility. Fertility gains also vary spatially, as we find an additional strong effect of the stream from which females were collected. Responses were unaffected by male mating history (males kept with females or in male‐only groups). Recent male mating may be of lesser importance because males in many species, including T. dalmanni, partition their ejaculate to maintain their fertility over many matings. This study highlights the importance of complementing laboratory studies with data on wild‐caught populations, where there is considerable heterogeneity between individuals. Future research should focus on environmental, demographic and genetic factors that are likely to significantly influence variation in individual female fecundity and fertility.     

Reproductive costs of mating with a sibling male: sperm depletion and multiple mating in Cephalonomia hyalinipennis

Polygynous parasitoid males may be limited by the amount of sperm they can transmit to females, which in turn may become sperm limited. In this study, I tested the effect of male mating history on copula duration, female fecundity, and offspring sex ratio, and the likelihood that females will have multiple mates, in the gregarious parasitoid Cephalonomia hyalinipennis Ashmead (Hymenoptera: Bethylidae: Epyrinae), a likely candidate for sperm depletion due to its local mate competition system. Males were eager to mate with the seven females presented in rapid succession. Copula duration did not differ with male mating history, but latency before a first mating was significantly longer than before consecutive matings. Male mating history had no bearing on female fecundity (number of offspring), but significantly influenced offspring sex ratio. The last female to mate with a given male produced significantly more male offspring than the first one, and eventually became sperm depleted. In contrast, the offspring sex ratio of first‐mated females was female biased, denoting a high degree of sex allocation control. Once‐mated females, whether sperm‐depleted or not, accepted a second mating after a period of oviposition. Sperm‐depleted females resumed production of fertilized eggs after a second mating. Young, recently mated females also accepted a second mating, but extended in‐copula courtship was observed. Carrying out multiple matings in this species thus seems to reduce the cost of being constrained to produce only haploid males after accepting copulation with a sperm‐depleted male. I discuss the reproductive fitness costs that females experience when mating solely with their sibling males and the reproductive fitness gain of males that persist in mating, even when almost sperm‐depleted. Behavioural observations support the hypothesis that females monitor their sperm stock. It is concluded that C. hyalinipennis is a species with a partial local mating system.     

Effects of male mating interval on spermatophore formation,transfer, and subsequent female receptivity and fecundity in the sorghum plant bug,Stenotus rubrovittatus

Males of the sorghum plant bug, Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae), transfer a spermatophore to females during copulation. After a 1‐day interval between the first and second copulation, males transferred both sperm and a spermatophore to females during the second copulation. However, when male mating interval was <1 h, they transferred sperm but no spermatophores to females during the second copulation. Therefore, the male mating interval probably produces two types of mated females, those with and those without a spermatophore. Mated females of S. rubrovittatus do not remate for at least 3 days after mating, even when courted, and lay more eggs than virgin females at the beginning of the oviposition period. The effects of spermatophores on female sexual receptivity and fecundity were examined using mated females with or without a spermatophore. Only one of the 40 (2.5%) mated females with a spermatophore remated, whereas 10 of the 26 (38.5%) without a spermatophore remated. Furthermore, mated females with a spermatophore laid more eggs than those without a spermatophore. These results suggest that spermatophores participate in reducing female sexual receptivity and enhancing female fecundity in S. rubrovittatus.     

Effect of age on reproductive attributes of an aphidophagous ladybird, Cheilomenes sexmaculata

The effect of both male and female age was investigated on certain reproductive attributes, viz. mating incidence, mating duration, fecundity, percent egg viability, ratio of reproductive and non‐reproductive periods and reproductive rate, of an aphidophagous ladybird, Cheilomenes sexmaculata (Fabricius). Females started mating at the age of 8 hours post‐emergence (PE) and males at the age of 2 days PE. Mating in the laboratory was a male‐dominated phenomenon. The mating duration and reproductive rate of 10‐day‐old females when mated with males of varying ages increased up to the male age of 60 days, and thereafter decreased, whereas, fecundity, egg viability and ratio of reproductive and non‐reproductive periods increased up to the male age of 50 days, and thereafter declined. However, when females of varying ages were mated with 10‐day‐old males, fecundity and reproductive rate increased up to 40 days of female age, respectively, then decreased. The ratio of reproductive and non‐reproductive periods increased with increasing age of females. Mating age for optimal reproductive output was 10J50‐day‐old males and NE to 40‐day‐old females. Reproductive cessation in males was recorded after 50 days PE, whereas in females at the age of 40 days PE. Higher mating durations lead to elevated reproductive rates. Delay in the reproductive phase was positively correlated with longevity. The results of this study may aid mass multiplication of this ladybird by identifying and promoting usage of adults of optimal age. Our results also enhance our understanding of the effect of age on reproductive attributes in ladybirds.     

Effects of delayed mating on the fecundity,fertility and longevity of females of diamondback moth,Plutella xylostella

Abstract The effects of delayed mating on the copulation duration, female fertility, fecundity, egg fertility, longevity and the number days alive after mating of females of diamondback moth (DBM), Plutella xylostella, were studied. When male mating was delayed, the female fertility, fecundity, egg fertility, longevity and number days alive after mating of DBM decreased, and there was a negative correlation between the age of the moth with those variables except copulation duration. When female mating was delayed, the female fertility, fecundity, percent egg fertility and number days alive after mating of DBM also decreased, but the longevity increased, which also showed a negative relationship between the age of the moth with the variables except copulation duration and longevity. When both males and females delayed mating, the female fertility and fecundity decreased; egg fertility was affected marginally, and the longevity of females increased. The moth age was negatively correlated with those variables.