Summary: Caloric restriction (CR) has been widely accepted as a mechanism explaining increased lifespan (LS) in organisms subjected to dietary restriction (DR), but recent studies investigating the role of nutrients have challenged the role of CR in extending longevity. Fuelling this debate is the difficulty in experimentally disentangling CR and nutrient effects due to compensatory feeding (CF) behaviour. We quantified CF by measuring the volume of solution imbibed and determined how calories and nutrients influenced LS and fecundity in unmated females of the Queensland fruit fly, Bactocera tryoni (Diptera: Tephritidae). We restricted flies to one of 28 diets varying in carbohydrate:protein (C:P) ratios and concentrations. On imbalanced diets, flies overcame dietary dilutions, consuming similar caloric intakes for most dilutions. The response surface for LS revealed that increasing C:P ratio while keeping calories constant extended LS, with the maximum LS along C:P ratio of 21:1. In general, LS was reduced as caloric intake decreased. Lifetime egg production was maximized at a C:P ratio of 3:1. When given a choice of separate sucrose and yeast solutions, each at one of five concentrations (yielding 25 choice treatments), flies regulated their nutrient intake to match C:P ratio of 3:1. Our results (i) demonstrate that CF can overcome dietary dilutions; (ii) reveal difficulties with methods presenting fixed amounts of liquid diet; (iii) illustrate the need to measure intake to account for CF in DR studies and (iv) highlight nutrients rather than CR as a dominant influence on LS.

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.

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.

The sterile insect technique (SIT) involves the inundative release of irradiated (sterile or partially sterile) insects to decrease population levels in a target pest species. The effectiveness of SIT programs depends on sterile males mating successfully and inducing reproductive failure in wild females, or in the F1 generation in the case of lepidopteran species. Thus, from the perspective of insect control, female mating failure involves mating with a mass‐reared, sterilized male, which then results in female reproductive failure. Here, we review female mating failure in the context of SIT at two stages. First, at the pre‐copulatory stage we consider factors that affect female mating failure with sterile males, such as differences between sterile and wild males in terms of male courtship success, male discrimination of females, pheromone production, and dispersal. We emphasize studies with some degree of ecological realism and review certain factors that can affect female sexual development and choice, such as diet, age, and sex ratio. Second, at the post‐copulatory stage we consider factors that functionally result in female reproductive failure, such as ejaculate transfer and control of female remating. Sterile insect technique operations strive to incorporate methods that increase wild female mating with sterile males so that ultimately population‐wide reproductive failure is achieved in the target species.

The sterile insect technique (SIT), an environmentally friendly means of control, is currently used against plant, animal, and human pests under the area-wide integrated pest management. It consists in the mass production, sterilization, and release of insects in an affected area where sterile males mate with wild females leading to no reproduction. Here, we review SIT in the Neotropics and focus on particular recent successful cases of eradication of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), as well as effective programs used against the Mexican fruit fly Anastrepha ludens (Loew), the New World screwworm fly Cochliomyia hominivorax (Coquerel)), and the Cactus moth Cactoblastis cactorum (Berg). We examine when SIT does not work and innovations that have made SIT more efficient and also highlight complimentary techniques that can be used in conjunction. We address potential candidate species that could be controlled through SIT, for example Philornis downsi Dodge & Aitken. Finally, we consider the impact of climate change in the context of the use of the SIT against these pests. Given the recent dramatic decline in insect biodiversity, investing in environmentally friendly means of pest control should be a priority. We conclude that SIT should be promoted in the region, and leadership and political will is needed for continued success of SIT in the Neotropics.