Effect of larval density and substrate quality on the wing geometry of Stomoxys calcitrans, Linneaus 1758 (Diptera: Muscidae).

Abstract

Background: In insects, oviposition decisions may lead to egg deposition in substrates with diferent larval density and nutritional levels. Individuals developing in such substrates may present plasticity in their phenotype. Here, we investigated the efect of two factors related to oviposition decisions, namely larval density and substrate quality, on the wing size and wing shape of the stable fy, Stomoxys calcitrans L. (Diptera: Muscidae). Methods: We reared S. calcitrans larvae at diferent densities (5, 15 and 25) and on diferent substrates (camel, cow, donkey and sheep dung). For each fy that emerged, we recorded body weight, and detached, slide-mounted and photographed the right wing. Next, we collected 15 landmarks on each photographed wing, and applied geometric morphometric analysis to assess variation in wing size and wing shape of S. calcitrans across the diferent larval densities and substrate types. Results: We observed that wing size and wing shape of S. calcitrans were afected by larval density and the nature of the developmental substrate. Flies reared in a group of 5 had larger wing centroid size, wing length, wing width, wing area and wing loading compared with those reared in a group of 25. Also, flies developed in donkey and sheep dung had larger wing centroid size, wing length, wing width, wing area and wing loading in comparison with those grown in camel and cow dung. Canonical variate analysis followed by discriminant analysis revealed signifcant wing shape variation in S. calcitrans across the diferent densities and substrates. Wing size had a signifcant but weak positive efect on wing shape. Conclusions: This study demonstrates the high sensitivity of S. calcitrans wings to variation in larval density and developmental substrate, and that use of landmark-based geometric morphometric analysis could improve our understanding of how flies of veterinary importance respond to environmental variability.