Parental effects of Bt toxin and vitamin A on Helicoverpa armigera

The increase in the area cultivated with vitamin-enriched transgenic crops producing Bt toxin raises the question of whether the addition of vitamins will in any way mitigates the effect of the toxin on the phytophagous insects that feed on those crops. On the other hand, the parental effect that feeding on these enriched transgenic crops may have on the offspring of the phytophagous that survive on them is not well known. In this work, the effect of vitamin A (beta-carotene) addition to diets with or without Bt toxin on Helicoverpa armigera larvae and their offspring was determined. The addition of vitamin A did not have any beneficial effect either for the larvae fed on enriched diets nor for their offspring. However, parental effects due to dietary feeding with the toxin were detected since adults from larvae fed on the Bt diet had higher mating success than those fed on the toxin-free diet, although there were no differences on the fertility of mated females regardless of whether their previous larvae fed on the Bt or non-Bt diet. A certain adaptive effect to the toxin was also noted since the mortality of larvae whose previous generation fed on diet with Bt was lower than that of the larvae that came from larvae fed on a non-Bt diet. It would be interesting to determine if H. armigera adults prefer to mate and lay eggs in the same type of crops in which they have developed or if feeding on different crops, such as corn or alfalfa, causes different paternal effects on the offspring. These aspects can be of great importance in the development of resistance of this species to the Bt toxin.

Automated summary

The addition of vitamin A to diets with or without Bt toxin did not have any beneficial effect on both the larvae and their offspring of Helicoverpa armigera. However, adult mating success was higher in larvae fed on the Bt diet, and a certain adaptive effect to the toxin was observed as the mortality rate of larvae from previous generations fed on the Bt diet was lower. These findings are important for the development of resistance of this species to the Bt toxin.