Wing Morphology of Boll Worm and Other Related Species

Boll worm (Bodie) is a major pest to cotton agriculture costing between $20 and 30 per acre in yield loss and treatment, annually. Several studies have focused on boll worm characteristics and physiology in relation to local environmental response and crop resistance. However, studies on characteristics related to dispersal are few despite the fact that boll worm are well known for long distance migrations during the spring and fall months. Here we assess the wing morphology and venation of Boll worm (Helicoverpa zea) and related these findings to known mechanistic principles associated with wing mechanics and potential for dispersal behavior. Additionally, we compared these findings to those of other closely related Helicoverpa and Heliothis species, including Helicoverpa armigera (Hübner) (a recently invasive boll worm to the Americas originating from Europe), Helicoverpa assulata (Guenée), Helicoverpa hawaiiensis (Quaintance & Brues) Helicoverpa geletopoen (Dyar) and Heliothis virescens (Fabricius). We combined the use of classical morphometric analyses including; body size, wing area, aspect ratio as well as geometric morphometric analyses of forewing venation using pictures taken with a high power digital camera mounted on a microscope and 5 digitize landmarks. Linear regression and constrained ordination were used to statistically test variation in wing morphology among species. We found significant differences in wing morphology and body size among species, however the wing to body-size relationship was not constantly correlated suggesting different movement strategies for the different species, which likely relates to differences in foraging behavior and seasonal migratory patterns. Overall, these findings highlight the variation in potential dispersal ability across species and indicate control of boll worm and other closely related species needs to consider spatial ecology.