Developmental Responses to Food Limitation as Indicators of Environmental Conditions for Ephydra Cinerea Jones (Diptera)

Publisher Website
Google Scholar
Abstract
Adaptive developmental responses to suboptimal conditions should preserve the life history traits most important to fitness at the expense of less critical traits. This paper compares responses to food limitation of Ephydra cinerea Jones (new data) to those of other Diptera (literature data) and concludes that the differences are indeed related to differences in demographic situations and other environmental characteristics. All the flies surveyed respond to larval food limitation by sacrificing adult body size, fecundity, and development time; these responses will moderate increases in prereproductive mortality, which demographic analyses identify as the most influential component of fitness for all the species. Differences between E. cinerea and the other flies in the degree to which: (a) body size is reduced, (b) development time is extended, and (c) mass—relative reproductive investment is increased under larval food limitation are associated with differences in: (a) the importance of size—related adult social interactions and range of larval food availability, (b) the safety of larval environments, and (c) demographic conditions. Similar comparisons generated predictions that, in comparison to other higher Diptera, adult size should be unusually important to fitness in house flies (Musca domestica), and the risks of mortality late in the larval period should be unusually high in the natural environments of blowflies (Chrysomyia spp., Lucilia spp.). Adult life—span and fecundity of fly species with poor access to adult food are relatively insensitive to reductions in adult food availability. Similarly, starvation resistance of newly enclosed larvae is correlated with the difficulty larvae have in locating food in nature, while absolute and relative egg size are not. In contrast to some other insects and mites, all the flies surveyed maintain nearly constant egg size (and where measured, egg quality) over a wide range of larval food limitation, suggesting that reduced egg size would have drastic effects on larval success. Where environmental data are available for the flies, conditions would favor evolution of near minimal investment per offspring.