Postcopulatory Behavior of Tephritid Flies

Mating produces profound changes in the behavior of female flies, such as an increase in oviposition, reduction in sexual receptivity, increase in feeding, and even excretion. Many of these changes are produced by copulation, sperm, and accessory gland products that males transfer to females during mating. Our knowledge on the function of the male ejaculate and its effect on female insects is still incipient. In this article, we review peri- and postcopulatory behaviors in tephritid flies. We address the effects of male copulatory behavior; copula duration; and the male ejaculate, sperm, and accessory gland products on female remating behavior. Many species from these families are pests of economic importance; thus, understanding male mating effects on female behavior contributes to both developing more effective environmentally friendly control methods and furthering our understanding of evolutionary implications of intersexual competition and sexual conflict.Fil: Perez Staples, Diana Folger. Universidad Veracruzana. Instituto de Biotecnología y Ecología Aplicada; MéxicoFil: Abraham, Solana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Female remating behaviour in pest tephritid fruit flies and its implication for the sterile insect technique

The efficiency of the Sterile Insect Technique (SIT)targeting tephritid fruit flies depends not only on sterile males mating withwild females, but also on their ability to transmit an ejaculate and inhibitfemale remating. Methods: Here we review female remating in tephritidflies of economic importance, inhibition of female remating by males and focuson the factors that can modulate post-copulatory mating behaviour.Results: Remating by females can vary greatly between fruit fly species, bothin mating frequency and time elapsed between matings (sexual refractoryperiod). While some species seem to be monandrous, others vary in their degreeof polyandry -- ranging from only two matings in their lifetime to 8 matingsper day. Remating inhibition can occur through sperm, accessory gland products (AGPs)or copulatory courtship. However, the mechanisms by which males inhibit femalemating are still poorly understood.  Conclusions: Despitemany studies on the sexual behaviour of tephritids, we still know little aboutthe processes occurring during the copula and how the different components ofthe ejaculate can affect female post-copulatory behaviour. AGPs have been shownto affect mating inhibition in C. capitata, B. tryoni and A.fraterculus but not in A. ludens. Thus, the effect of male AGPsshould not be generalized throughout tephritids. Understanding how AGPs modifyfemale post-copulatory behaviour can be useful in developing alternativecontrol tactics such as the use of antiafrodisiac substances.Fil: Abraham, Solana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Herrera Cruz, Mariana. Universidad Autonoma de Benito Juarez de Oaxaca (univ. A. B. Juarez de Oaxaca); MéxicoFil: Perez Staples, Diana Folger. Universidad Veracruzana. Instituto de Biotecnología y Ecología Aplicada; México9th International Symposium on Fruit Flies of Economic ImportanceBangkokTailandiaInternational Fruit Fly Steering Committe

Ejaculate allocation and female remating in a tropical tephritid fruit fly

Males that copulate repeatedly may suffer from reduced sperm stores. However, few studies have addressed sperm depletion from both female and male perspectives. Here, we show that male Anastrepha obliqua (Diptera: Tephritidae) do not ejaculate all available sperm and are left with mature sperm in the seminal vesicles even after copulating as often as three times in half a day. Ejaculate size was not related to male mating history, time elapsed since mating, copulation duration, female thorax length or head width. a repeatability analysis revealed that males were consistent in the amount of sperm they allocated to virgin females. This suggests that males cannot deliver consistent amounts of accessory gland products (AGPs), which are transferred in the ejaculate together with sperm. AGPs are known to inhibit female remating in other insects. results suggest that males strategically allocate similar numbers of sperm among successive mats without exhausting sperm reserves for future encounters, but may suffer from AGP depletion. We discuss the role that differential sperm storage and excess sperm may have in mediating sperm competition and tie our results to the unique natural history of A. obliqua.1 page(s

Patterns of sperm precedence in Queensland fruit fly (Bactrocera tryoni): effects of male size and copulation duration

Sperm competition and selection can be studied through observation of non-random differential fertilization success, or sperm precedence, among mating males. Sperm precedence is typically measured as the proportion of progeny sired by the second mate to mate with a with a sequentially mated female, termed the P2-value.1 page(s

Post-teneral protein feeding enhances sexual performance of Queensland fruit flies

Adult diet is an important determinant of sexual activity in many tephritid fruit flies. Whether availability of protein (hydrolysed yeast) in addition to sucrose influences sexual activity or longevity of male and female Queensland fruit flies (Bactrocera tryoni Froggatt, 'Q-flies'), and whether irradiation of flies as pupae modifies their dietary needs, is investigated. Previous studies on groups of flies suggest that protein is required for sexual maturation of females but not males. By contrast, this study of individual flies demonstrates that protein in the adult diet provides a massive boost to sexual activity of both males and females. Mating probability increases with age from 4-14 days as the flies began to mature. However, mating probability reaches much higher levels when the flies are provided with protein. Although males and females mate at similar rates when provided with protein, females suffer a greater reduction in mating probability than males when deprived of protein. In addition to increased mating probability, access to dietary protein is also associated with reduced latency from onset of dusk until copulation. Furthermore, young male flies with access to dietary protein have longer copula duration than males fed only sucrose. Irradiation of flies as pupae has no apparent effect on mating probability, the latency to copulate or copula duration. However, when deprived of protein, sterile flies (especially males) suffer a greater reduction in longevity compared with fertile flies. Overall, access to dietary protein increases longevity for both males and females, although females live longer than males on both diets. These findings suggest that prerelease provision of dietary protein has the potential to greatly enhance the efficacy of Q-flies used in the sterile insect technique.8 page(s

Feeding on yeast hydrolysate enhances attraction to cue-lure in Queensland fruit flies, Bactrocera tryoni

Feeding on yeast hydrolysate (a source of nitrogen) has a strong influence on the physiology and behaviour of the Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), affecting longevity, sexual maturation, oogenesis, and mating performance. In this study, we demonstrate that access to yeast hydrolysate also influences the development of attraction to cue-lure in Q-flies. We provided virgin Q-flies various periods of access to yeast hydrolysate (continuous, 48 h, 24 h, or deprived). Attraction of males to cue-lure was increased and occurred at an earlier age when they were fed yeast hydrolysate. Males given continuous access were strongly attracted to cue-lure at a younger age (8 days after emergence), but by 12 days after emergence attraction of males given access to yeast hydrolysate for 48 h did not differ from males given continuous access. Attraction by males deprived or given just 24 h access to yeast hydrolysate was always significantly lower than those of males with continuous access. Male attraction to cue-lure was highest in the early morning. While cue-lure is most often thought of as a male attractant, virgin female Q-flies were caught in cue-lure traps at dusk at ages when they are known to be sexually mature. We suggest that cue-lure or similar natural chemicals play a role in the Q-fly mating system. γ-Irradiation used to induce sterility had no significant effect on attraction to cue-lure by Q-flies.10 page(s

Enforced monogamy in female Queensland fruit flies, do remating decisions influence reproductive success?

Multiple mating by females is common in many insects. However, there is still considerable debate as to the potential benefits of additional matings for females. Males may sire additional offspring with every mating, whereas females could potentially fertilize all her gamets in a single mating. Furthermore, females may incur lifespan costs with every mating. Thus, it is still not clear whether females benefit by mating with more than one male. Here, we explored the consequences of enforced monandry in Queensland fruit fly females, Bactrocera tryoni (Diptera: Tephritidae) by measuring their lifetime fecudity, fertility and longevity, Females where virgin or allowed to mate once or twice with either a normal or a sham male (ablated aedeagus). Sham males could mate but were unable to transfer sperm or accessory gland products (AGPs). To further explore the consequences of female mating decisions, we also included females that rejected either the initial or second male. Contrary to other studies, we found no evidence that enforcing monandry on females effected lifetime fecundity, fertility or egg laying rate. However, females that mated once or twice with normal males were more likely to lay eggs, and laid more eggs than virgin females or females mated to sham males. This suggests that female postcopulatory decisions such as oviposition are mediated in part by substances transferred during mating or by the act of mating per se.1 page(s

Olfactory response to cue-lure in Queensland fruit flies is enhanced by protein feeding

Sexual performance of male and female Queensland fruit flies (Q-flies) is greatly enhanced by protein feeding, most likely due to increased maturation rates. We here present new findings demonstrating that olfactory response of these flies to the attractant 'cue-lure' is also enhanced by protein feeding. We tracked development of attraction to cue-lure by virgin Q-flies given various periods of access to dietary protein (continuous, 48 hrs, 24 hrs, no access). Both males and females showed increased attraction as they aged and matured. Flies with continuous access to protein were least attracted. Whereas males tended to approach cue-lure traps in the morning, females tended to respond at dusk. This sex difference is consistent with the possibility that cue-lure resembles natural chemicals on which males feed and use as precursors for sex pheromones. The implications of these results for Q-fly reproductive behavior and management will be discussed.1 page(s

Protein: carbohydrate ratios promoting sexual activity and longevity of male Queensland fruit flies

Nutrition is commonly a powerful determinant of sexual performance in insects, and recent studies have found this to be the case in Queensland fruit flies (Tephritidae: Bactrocera tryoni Froggatt; 'Q-flies'); male Q-flies allowed to self-regulate intake of yeast hydrolysate, a rich source of amino acids and vitamins used in most mass-rearing programmes (protein) and sucrose (carbohydrate), had greatly enhanced sexual performance compared with males provided only sucrose. While some yeast hydrolysate is clearly beneficial for the sexual performance of adult male Q-flies, the questions of what proportion of yeast hydrolysate in the diet is sufficient to yield full benefits, or is too much, have not yet been addressed. To address these questions, the present study assessed sexual performance and longevity of adult male Q-flies maintained on diets containing various proportions of yeast hydrolysate and sucrose. Male Q-flies maintained as adults on dry mixtures containing 9%, 17% or 25% yeast hydrolysate had mating probability, mating latency, copula duration and longevity similar to those provided yeast hydrolysate and sucrose in separate dishes and allowed to self-regulate intake. As in previous studies, while longevity was unaffected we found a marked reduction in sexual performance when the flies were completely denied access to yeast hydrolysate, and the few that did mate had relatively short copulations. At the other extreme, flies receiving diets with high levels of yeast hydrolysate (50%, 75%, 83% and 91%) suffered marked reductions both in longevity and in mating performance.8 page(s