Wing Shape as an Indicator of Larval Rearing Conditions forAedes albopictusandAedes aegypti(Diptera: Culicidae)

Abstract

Estimating a mosquito's vector competence, or likelihood of transmitting disease, if it takes an infectious bloodmeal, is an important aspect of predicting when and where outbreaks of infectious diseases will occur. Vector competence can be affected by rearing temperature and inter- and intraspecific competition experienced by the individual mosquito during its larval development. This research investigates whether a new morphological indicator of larval rearing conditions, wing shape, can be used to distinguish reliably temperature and competitive conditions experienced during larval stages. Aedes albopictus (Skuse) and Aedes aegypti (L.) (Diptera: Culicidae) larvae were reared in low intraspecific, high intraspecific, or high interspecific competition treatments at either 22 or 32 degrees C. The right wing of each dried female was removed and photographed. Nineteen landmarks and 20 semilandmarks were digitized on each wing. Shape variables were calculated using geometric morphometric software. Canonical variate analysis, randomization multivariate analysis of variance, and visualization of landmark movement using deformation grids provided evidence that although semilandmark position was significantly affected by larval competition and temperature for both species, the differences in position did not translate into differences in wing shape, as shown in deformation grids. Two classification procedures yielded success rates of 26 - 49%. Accounting for wing size produced no increase in classification success. There seemed to be a significant relationship between shape and size. These results, particularly the low success rate of classification based on wing shape, show that shape is unlikely to be a reliable indicator of larval rearing competition and temperature conditions for Ae. albopictus and Ae. aegypti.