Macronutrient regulation and performance in the cotton bollworm (Helicoverpa zea)

Feeding on over 100 different crop species, the cotton bollworm (Helicoverpa zea) is one of the most ubiquitous pest species in North and South America. Although the use of Bt cotton has been effective in controlling lepidopteran pests, H. zea is remains the most difficult heliothine species to control. Understanding the nutritional physiology of this species is important for determining the mechanisms that contribute to their host range, and for predicting when and where outbreaks will occur in agricultural systems. The geometric framework (GF) has been widely used to document protein and carbohydrate regulation and its effect on performance in order to identify nutritional constraints on insect fitness. Although nutrient regulation and performance patterns have been recorded across a range of different insect taxa, no GF study has been applied to any heliothine species, despite the economic importance of this subfamily. The objectives of this study was to identify the optimal diet for H. zea, in terms of protein and carbohydrates, and to determine how feeding on sub-optimal diets affects performance, such as mass gain and developmental time. This was accomplished using both choice and no-choice experiments.