Detecting effects of larval competition and temperature on shape of mosquito wings

Changes in larval competition and temperature in mosquitoes can produce changes in adult size and shape. Such changes are commonly assessed by measuring wing length. However, competition and temperature effects on wing length are similar, so wing length alone does not provide a useful index of the impact of competition on mosquitoes. My research goal is to find measurements that can be used to detect effects of competition among larvae on adults.

 

A promising method is analysis of shape using Procrustes superimposition to create digital landmarks, which are used to generate shape variables. Shape variables can be used to determine if larval rearing conditions change wing shape. If successful, this approach could be useful as an index of competition stress in natural populations, which may be important as competition can impact vector competence in mosquitoes.

 

To test for the effects of temperature and competition on wing shape, Aedes albopictus and Aedes aegypti were reared in one of three competition treatments (low intraspecific, high intraspecific and high interspecific) and one of two temperatures. The two species changed wing shape in different ways (p=2.22x10^-16). For A. aegypti, temperature and density treatments produced significant effects (p=0.0249 and p=0.0308), with no significant interaction. For A, albopictus, temperature and density treatments produced significant effects (p=3.51x10^-9 and p=0.0001), and the interaction produced two significant canonical variates, corresponding to temperature and density (p=2.26x10^-9 and p=0.0019). Thus, wing shape measurements can distinguish between effects of temperature and density for A. albopictus.