Meeting Abstract
Holometabolous insects have lives divided into discrete stages, with larvae that are largely dedicated to feeding and growth, and adults that are usually dedicated to dispersal and reproduction. In a laboratory setting holometabolous insects are generally well fed, and therefore reach a large and uniform adult size. But larvae in the wild often rely on ephemeral food sources, subject to the risks of unpredictable desiccation, temperature shifts, competition, and predation. They may often be motivated to pupate earlier, which will result in smaller adult sizes. This carries important consequences, especially for vision, which is highly sensitive to eye size. But despite the ubiquity of uncertain nutrition in the wild, and tremendous study on flight in the lab, these natural allometric effects on fruit fly vision have rarely been considered. We found that wild reared fruit flies have highly variable sizes compared to their counterparts reared in the lab, and that their generally smaller eyes are composed of facets that are both smaller and less numerous. This is significant for an animal with already poor resolution that frequently flies in dim light. Small facets produce less light catch and increased diffraction, while fewer facets reduce spatial acuity and possibly field of view. These changes affect both visual sensitivity and total image information, which in turn compromises the perception of dim, fast, and high frequency spatial patterns.
