Effects of male condition on fitness in two tropical tephritid flies with contrasting life histories

We investigated the effects of male size and adult diet on male sexual competitiveness and lifetime reproductive success of female mates in two tephritid flies with contrasting natural histories, the Mexican fruit fly, Anastrepha ludens, and the guava fruit fly, A. striata. Small, medium and large males received either a low-quality diet (sucrose offered every third day) or a high-quality diet (sucrose and protein offered ad libitum). Regardless of size or species, males on the high-quality diet copulated significantly more often across the 4 observation days than males on the low-quality diet. For A. ludens, both size and diet influenced territory defence by resident males, but only size affected the likelihood of success by invading males. Females that copulated with a low-quality fed male had significantly shorter maximum longevity, although there was no effect of male diet on the proportion of eclosed eggs. For A. striata, diet, but not size, influenced territory defence by invading males. Females discriminated strongly against males fed a low-quality diet but not against smaller males. However, females that copulated with medium and small males had lower fecundities than those copulating with large males. We discuss the costs for females of mating with smaller males and their inability to distinguish between males of different conditions, as well as interspecific differences in mate choice and postcopulatory consequences for females in terms of the ecological differences that distinguish these two species. (C) 2008 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.