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.     

Variation in floral longevity in the genus Leptosiphon: mating system consequences

Pollination or fertilisation trigger floral senescence in a wide range of flowering plants, and yet little attention has been given to the implications of this phenomenon to mating system evolution. We examined the effects of pollination on floral senescence in the genus Leptosiphon. Species in the genus exhibit a wide range of breeding systems. In all cases, compatible pollination induced senescence; emasculated flowers lived longer than hand‐outcrossed flowers. In the self‐compatible species, Leptosiphon acicularis and L. bicolor, and in one highly selfing population of L. jepsonii, unmanipulated flowers had reduced longevity compared to emasculated flowers, suggesting that autonomous self‐pollination limits floral longevity in these species. Limited floral longevity in these highly selfing taxa may reduce opportunities for male outcross success, representing a possible source of selection on the mating system. In turn, the mating system might influence how selection acts on floral longevity; obligately outcrossing taxa are expected to benefit from longer floral longevities to maximise opportunities for pollination, while selfing taxa might benefit from earlier floral senescence to reduce resource expenditure. Overall, the longevity of unpollinated flowers increased with the level of outcrossing in the genus Leptosiphon. Our results taken together with those of a previous study and similar results in other species suggest that floral longevity may represent a largely unexamined role in mating system evolution.     

Multiple mating and inseminating potential of Glossina pallidipes

In the tsetse fly Glossina pallidipes Austen multiple mating of females and the inseminating capacity of males was investigated with the aim of economizing on the number of males in mass rearing. Forty five percent of mated but uninseminated females and 9% of inseminated females remated.Virgin males inseminated four times in succession and remained eager to copulate thereafter. Restoration of the inseminating ability took 2 h rest. Experienced and virgin males were equally successful at mating. Insemination occurred during the last 30 s of the copulation and one male inseminated nine females on the average. Females mated in a 1:1 or a 1:3 / ratio were equally productive. The females that were mated in a 1:3 ratio survived better.Series of three successive matings, alternated with periods of rest, showed that the males did not regain their original inseminating capacity. In the first series all three mates were inseminated, but in subsequent series only the first and the second. An efficacious reduction of the number of males to 20% of the number of females to be mated may be possible by using the males first in a 1:3 and subsequently in a 1:2 / ratio.

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Résumé Afin d'économiser le nombre de mâles à maintenir dans des élevages de masse pour des études sur les méthodes de protection contre Glossina pallidipes, les accouplements multiples des mâles et des femelles ont été étudiés au laboratoire.7 à 9 jours après leur émergence, les femelles ont eu pour la première fois la possibilité de s'accoupler avec des mâles vierges ou non. La réceptivité lors des accouplements ultérieurs a été testée immédiatement après le premier accouplement. 45% des femelles non inséminées se réaccouplent. Parmi les femelles inséminées, seulement 9% copulent à nouveau dans les 6 h qui suivent le premier accouplement.Les mâles présentés à une succession de femelles restaient avides de copuler, mais la majorité était incapable de les inséminer après la 4ème copulation; la restauration du pouvoir fertilisant demandait une période de repos de 2 h.En laboratoire, les mâles vierges ou expérimentés ne présentaient aucun avantage sexuel les uns par rapport aux autres. Les femelles semblaient avoir été inséminées dans les 30 dernières secondes de la copulation.Aucune différence de productivité n'a été observée quand les accouplements ont eu lieu avec 1 mâle pour 1 ou 3 femelles.Des séries de 3 accouplements successifs, alternant avec des periodes de repos, ont montré que le pouvoir fertilisant ne retrouvait pas son niveau initial. Dans les premières séries, toutes les 3 femelles ont été inséminées, mais dans les séries ultérieures seulement la 1ère et la 2nde. En moyenne, un maximum de 9 femelles était inséminé, marqué par un remplissage de la spermathèque de plus de 50% ou une fécondité supérieure à 0,8. Une réduction efficace du nombre de mâles, au cinquième de celui des femelles à accoupler, est possible en utilisant d'abord 1 mâle pour 3 femelles et ensuite 1 mâle pour 2 femelles.

     

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.     

Copulation reduces male but not female longevity in Saltella sphondylli (Diptera: Sepsidae)

Mating more than once is extremely costly for females in many species, making the near ubiquity of polyandry difficult to understand. However, evidence of mating costs for males is much rarer. We investigated the effects of copulation on longevity of male and female flies (Saltella sphondylli). We also scrutinized potential fecundity and fertility benefits to females with differing mating history. Copulation per se was found to decrease the longevity of males but not that of females. However, when females were allowed to lay eggs, females that mated died earlier than virgin females, indicating costs of egg production and/or oviposition. Thus, although longevity costs of copulation are higher for males, reproduction is nevertheless costly for females. We also found no differences in fecundity or fertility relative to female mating history. Results suggest that polyandry may be driven by minor costs rather than by major benefits in this species.     

Strong material benefits and no longevity costs of multiple mating in an extremely polyandrous leaf beetle, Chrysochus cobaltinus (Coleoptera: Chrysomelidae)

It is well established that females of many species exhibitpolyandry. Although such behavior often increases female fitnessby augmenting fecundity or enhancing the genetic diversity andvigor of their offspring, it often reduces female longevity.It has been argued that trade-offs between these costs and benefitsshould limit the degree to which females remate. However, theexistence of highly polyandrous species suggests substantialpolyandry benefits and/or minimal costs in some systems. Femalesof the leaf beetle, Chrysochus cobaltinus, are extremely polyandrous,providing an opportunity to examine the factors influencingthe evolution of such behaviors. We compared the fecundity andlongevity of singly mated females, females that mated multipletimes with the same male, and females that mated multiple timeswith different males. Compared with females in the single matingtreatment, females in both multiple mating treatments exhibiteda significant reduction in latency to oviposition and, due toan increase in daily egg production, significant increases inlifetime fecundity. This difference diminished as the time sincelast mating increased. There were no differences in fecunditybetween the 2 multiple mating treatments, indicating that mateidentity does not influence the material benefits of multiplemating. Surprisingly, female longevity did not differ amongtreatments. The pronounced fecundity benefits that females gainfrom multiple mating, coupled with a lack of longevity costs,apparently explains the extreme polyandry in this species. Inaddition, the existence of material fitness benefits via conspecificmatings raises the intriguing possibility that in a C. cobaltinus–Chrysochusauratus hybrid zone, heterospecific matings may confer similarbenefits to Chrysochus females.     

Multiple mating and its effect on the reproductive success of female Epiphyas postvittana (Lepidoptera: Tortricidae)

Abstract.

• 1 Multiple mating and its effect on reproductive performance of female Epiphyas postvittana (Walker) moths were studied under controlled conditions.
• 2 The age at which the moths mated for the first time ranged from the first to the tenth day after emergence, but 71% of first matings were during the first 3 days.
• 3 The majority (63%) of females had one or two spermatophores in the bursa copulatrix. Some (24%) were found with three to five spermatophores, whereas no successful mating occurred among 13% of individuals. The number of matings was partly dependent on the number of mates available to the female. Between the range of sex ratios of one male to one female and four males to one female maximal mating success occurred at the ratio of three males to one female.
• 4 Virgin females were capable of egg-laying, but mating stimulated and accelerated oviposition. Mated individuals laid twice as many eggs as unmated ones.
• 5 The level of copulatory activity did not influence the longevity of females irrespective of the number of males available to them.
• 6 Sex ratios with greater than one male to a female improved the reproductive success by marginally increasing fecundity and fertility.
• 7 It is concluded that multiple mating would enhance population growth, and is of particular benefit to populations with a preponderance of females, as is known to occur naturally in this species.

     

Longevity cost of reproduction for males but no longevity cost of mating or courtship for females in the male-dimorphic dung beetle Onthophagus binodis

Life history theory predicts a trade-off between current and future reproduction. Despite a wealth of research on the cost of reproduction for females, there have been very few studies that have looked at the cost of reproduction for males. Longevity is closely related to the opportunity for future reproduction, and thus decreased longevity in response to current reproductive effort has been used as a measure of the cost of reproduction. Here we examine the cost of reproduction for males and females in the dung beetle Onthophagus binodis. Like many onthophagines, O. binodis exhibit dimorphic male morphology; major males develop a large pronotal horn while minor males remain hornless. Alternative morphologies are associated with alternative reproductive tactics. Thus, we ask whether major and minor males pay different costs of reproduction. We found that in contrast to previous work on Diptera, mating is not costly in terms of reduced longevity for female dung beetles. Despite a longevity cost of reproduction for males, we found no evidence for differential longevity costs associated with alternative reproductive tactics.     

Host influence on mating behavior and spermatophore reception correlated with reproductive output and longevity of femaleEarias insulana (Boisduval) (Lepidoptera: Noctuidae)

When mating and oviposition behavior ofEarias insulana were studied in the absence or presence of host or by providing only host odor, in comparison to other treatments host absence caused a delayed and reduced reproductive activity with occasional impairment of egg viability. Presence of host or its odor resulted in a short premating period and a significant increase in mating frequency, number of spermatophores transferred, number of eggs oviposited, and proportion of eggs fertilized. Compared to host odor, host accessibility had a larger impact on insect behavior, indicating the importance of host cantact. Under conditions of host accessibility, there existed a significant and positive correlation between the number of spermatophores received by a female and both the number of eggs she oviposited and her longevity. This indicated a role for male-derived nutrients in the reproduction ofE. insulana.     

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.     

The mating and reproductive biology of the freshwater planktonic calanoid copepod Eudiaptomus gracilis

1. Quantitative aspects of the mating and reproductive biology of the freshwater planktonic calanoid copepod Eudiaptomus gracilis, including duration and frequency of mating, duration of various phases of the oviducal cycle, egg production rate and adult longevity were studied under laboratory conditions. One set of copepods was fed the alga Chlamydomonas reinhardtii whose density was adjusted to 2 × 10⁵ cells mL^?1 (about 10 mg C L^?1), another set was fed a mixed diet consisting of natural plankton (copepod nauplii, small rotifers and large algae) in the size range of 50–150 μm (dry mass approximately 90 mg L^?1). 2. The entire mating process, from the grasping of the female by the male’s right geniculate antennule to the separation of the pair, lasted about 2 min. Spermatophore placement started at about 30 s to 1 min after mating began and took approximately 1 min. Immediately after the spermatophore had been fixed in the female’s genital segment, the pair separated. 3. The total oviducal cycle, including the gravid phase where the female carried ripe oocytes and the non‐gravid phase where the female did not carry ripe oocytes, lasted about 5–6 days. The non‐gravid phase was particularly long; it was longer than the gravid phase and constituted 62–72% of the total cycle. 4. Mating and spermatophore placement usually occurred with gravid females although occasionally (in 30 of 200 observations) spermatophores were attached in the genital segment of non‐gravid females. Generally two to four, but up to seven, spermatophores were observed at a female’s genital segment at the same time. 5. Clutch size, rate of egg production and adult longevity depended on food. When fed on C. reinhardtii, females carried 7–8 eggs clutch^?1, produced a mean of 1.3 clutches and lived 14 days on average. When fed natural mixed food, females carried 10 eggs clutch^?1, produced 5.6 clutches and lived 37 days on average. 6. Removal of males after the first clutch resulted in no further egg production. Re‐mating is necessary in E. gracilis for continuous clutch production and the production of fertile eggs. 7. Mating duration is comparatively short and the non‐gravid phase comparatively long in E. gracilis. This could be an adaption to the life in the pelagic zone of the lake, where fish predators are present. Fish select ovigerous females, pairs in copula and, probably, females with ripe oocytes which make them conspicuous. Thus, a short mating duration and a prolonged period without conspicuous oocytes, can be advantageous.     

Effects of the juvenile hormone mimic pyriproxyfen on female reproduction and longevity in the butterfly Bicyclus anynana

Female Bicyclus anynana butterflies given pyriproxyfen, a mimic of juvenile hormone, exhibited increased egg‐laying rates and early fecundity, but reduced longevity compared with control animals. Thus, pyriproxyfen application yielded antagonistic effects on different components of fitness, possibly demonstrating a juvenile hormone‐mediated trade‐off between present and future reproduction. Lifetime fecundity and egg size, however, showed no consistent response to pyriproxyfen, with lifetime fecundity being increased or decreased and egg size being reduced in one out of four experiments only. Females were most sensitive to pyriproxyfen around the onset of oviposition, coinciding with naturally increasing juvenile hormone titers in other Lepidoptera. Amounts between 1 and 10 µg pyriproxyfen were found to be effective, with, however, pronounced differences among experiments. This is attributed to differences in assay conditions. High pyriproxyfen concentrations (100 µg) as well as repeated applications of smaller amounts did not affect reproductive traits, but tended to reduce longevity.     

Effects of delayed mating and male mating history on longevity and reproductive performance of the rice stem borer, Chilo suppressalis (Walker) (Lep., Pyralidae)

Abstract:  The mating potential, effects of delayed mating and male mating history on longevity and reproductive performance of female rice stem borer (RSB), Chilo suppressalis , were investigated under laboratory conditions. Given the opportunity, RSB males copulated an average of 2.7 times, while females generally mated only once. Females were more severely affected by mating delay than males in terms of female longevity and reproductive performance. With increasing age at mating, females' longevity increased, while oviposition period, fecundity and egg fertility decreased. Mean fecundity and egg fertility of females mated 1 and 7 days after emergence were 251.3% and 99.2%, and 96.2% and 75.5% respectively. Both were reduced significantly when female mating was delayed beyond 4 days after emergence. However, irrespective of the first mating age and different mating history of the males, the results indicated that both did not result in a significant difference in the quality of their contributions to female longevity and reproductive performance. The results obtained in this study are discussed in relation to the potential effect on pheromone control of RSB.     

Multiple mating reduces male survivorship but not ejaculate size in the polygamous insect Stenomacra marginella (Heteroptera: Largidae)

In polygamous species, successful males should be able to inseminate multiple females, to defeat sperm from previous males, to avoid sperm displacement by other males, and to induce females to use his sperm during fertilization. Since resources are limited, adaptations to perform any of these functions may conflict with each other (and with other life-history traits) and trade-offs are expected to evolve. We studied if males of the polygamous true bug Stenomacra marginella face a trade-off between multiple mating and survivorship, by comparing the survivorship of virgin and multiply mated males. We also looked for physiological costs of ejaculate production by examining ejaculate production in consecutive matings in multiple mated males. Multiply mated males were able to produce ejaculates of similar size in up to six consecutive copulations but they had decreased survivorship in comparison with virgin males. There was no difference in survivorship between males mated three and six consecutive times, suggesting that the negative relation between survivorship and number of copulations is not linear. The decrease in survivorship seems to be a cost of mating and ejaculate production. This cost could favor the evolution of prudence in the allocation of resources to ejaculate production (e.g., cryptic male choice).     

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.     

Potential for pre-release diet supplements to increase the sexual performance and longevity of male Queensland fruit flies

1 Recent studies have shown that continuous access to a protein source (yeast hydrolysate) can greatly enhance the sexual performance of male Queensland fruit flies ( Bactrocera tryoni ; 'Q-flies'). However, in Sterile Insect Technique programmes used to eradicate or suppress wild populations, mass-reared Q-flies are typically fed only sucrose and water for up to 2 days before release.
2 We investigated whether adding a protein source to the diet of male Q-flies for a 24- or 48-h window after emergence and then removing it is sufficient to enhance mating probability, latency to mate, copula duration, probability of sperm storage, number of sperm stored, female remating tendency and longevity of male Q-flies.
3 Protein-fed males were more likely to mate than males fed only sucrose, especially when young. Protein-fed males also had shorter mating latencies and longer copulations than protein-deprived males.
4 Females mated by protein-fed males were more likely to store sperm, stored more sperm and were less likely to remate than were females mated by protein-deprived males. Females were also less likely to remate if their first mate had been large.
5 Overall, providing male Q-flies access to a protein source for a 24- or 48-h window early on in their adult life was sufficient to greatly enhance all assessed measures of performance. Although 24-h access was sufficient for a notable enhancement, further benefits were evident in males provided 48-h access.
6 The results are discussed in terms of the practical implications for Sterile Insect Technique programs used to eradicate or suppress wild Q-fly populations.     

Male mating strategies and the mating system of great-tailed grackles

Great-tailed grackles (Quiscalus mexicanus) are sexually dimorphic,dichromatic, colonially nesting blackbirds. In this study, males pursued three basic types of conditional mating strategies,each of which employed a different set of mating tactics. Territorialmales defended one or more trees in which several females nested.They achieved reproductive success by siring the offspringof their social mates and through extrapair fertilization.Resident males lived in the colony but did not defend territoriesor have social mates. Transient males passed through the colony, staying no more than a few days, and probably visited more thanone colony. Residents appeared to queue for access to territories,but transients did not. Residents and transients gained allpaternity through extrapair fertilizations and provided noparental care. Territorial males sired the majority of offspring,but residents and transients also sired small numbers of nestlings. Territorial males were larger and had longer tails than nonterritorialmales. The number of social mates was related to body size,and males that sired nestlings were heavier and had longertails than males with no genetic reproductive success. Malesthat gained paternity through extrapair fertilization wereheavier and had longer tails than males that did not. The matingsystem of great-tailed grackles can best be categorized as "non-faithful-female frank polygyny."