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We use unique experimental data on daily reproduction and survival of individual fruit flies from eight cohorts eclosed at different dates in 2004 and 2005 who were treated with varying proportions of sugar and yeast and subject to different caloric restrictions (CR). We investigate the relationship between eclosion date and longevity across diets and reproduction in Anastrepha ludens. We show that eclosion date can be associated with uncontrolled external or internal factor(s) which can modulate longevity of males and females independently of diet and reproduction to the extent similar to the effect of diet on longevity. The effect of diet manipulation on longevity is sensitive to date of eclosion with the role of CR in life extension ranging from beneficial to harmful. Interaction of date of eclosion with compositional changes of sugar and yeast but not with CR is responsible for life extension. Highly protein-enriched diets reliably maximize reproduction but not life span. Decreased longevity of flies treated with high-protein diets may be associated with harmful consequences of protein ingestion but is unlikely a result of high reproduction rates. We present evidence for the presence of two frailty-sensitive weakly interacting mechanisms of longevity in female flies associated with differences in predisposed fitness.

Male life history and resource allocation is not frequently studied in aging and life span research. Here, we verify that males of long-lived fruit-feeding butterfly species have reduced longevity on restricted diets [Beck, J., 2007. The importance of amino acids in the adult diet of male tropical rainforest butterflies. Oecologia 151, 741-747], in contrast to the common finding of longevity extension in dietary restriction experiments in Drosophila and some other organisms. Males of some of the most long-lived species of fruit-feeding butterflies were collected from Kibale Forest, Uganda, and kept on diets of either sugar or mashed banana. Seven out of eight species had non-significantly longer life spans on mashed banana diets. Data analysis using a time-varying Cox-model with species as covariate showed that males had reduced survival on the sugar diet during the first 35 days of captive life, but the effect was absent or reversed at more advanced ages. These results challenge the generality of dietary restriction as a way to extend life span in animals. We argue that such studies on males are promising tools for better understanding life history evolution and aging because males display a wider variety of tactics for obtaining reproductive success than females.

This study was concerned with the impact of different levels of artificial impairment (leg amputations) on male and female survival and female reproduction in the Mexican fruit fly, Anastrepha ludens . We monitored the demographic responses in a total of 100 flies of each sex that were maintained individually in 4 × 4 × 10 cm cages and subject to 1-of-11 different leg amputations (plus intact control) including cohorts in which either one front, one middle or one rear leg was severed (3 cohorts total), in which two legs were severed in different front–middle–rear combinations (6 cohorts total), or in which the two middle and one additional leg were severed (2 cohorts total). The two main findings were that: (i) although the effects on mortality of impairments were sex-specific, no universal patterns emerged that applied to either sex; and (ii) reproduction occurred in all cohorts of impaired females. Moderately-impaired flies (e.g. amputation of a single middle leg) laid nearly as many eggs in their lifetime as did intact controls. However, severely impaired flies (i.e. 3 legs amputated) laid significantly fewer eggs.

Information on the life span of organisms in the field is essential for elucidating the evolution of life span and aging. We present mark-recapture data (>30 000 marked individuals, >4000 recaptured at least once) on forty-seven species of fruit-feeding butterflies in a tropical forest in Uganda. The data reveal adult life spans in the field for several species that are significantly longer than previously recorded in Lepidoptera (butterflies and moths). Longevity records for species of which more than 100 individuals were recaptured ranged from 67 (Bicyclus auricruda) to 293 days (Euphaedra medon). In contrast to the majority of Lepidoptera which are short-lived, these all show exceptionally long life spans, and may thus help to better identify factors that affect aging, particularly when combined with information on temporal patterns in reproduction, strategies to avoid predation, and nutritional ecology. These key traits are readily measurable in butterflies and thus studies on fruit-feeding butterflies have much potential for gaining insight into the evolution of life span and aging, especially given the tradition of field-research on butterflies.