Effect of Gossypolone on the Growth and Development of Helicoverpa Zea

The cotton plant produces a group of structurally related terpenoid aldehydes in the pigment glands.  These compounds deter feeding by herbivorous insects.  The most extensively studied terpenoid is gossypol.  Gossypolone is a compound closely related to gossypol that was first reported in cotton by Paul Hedin and colleagues; however, its activity against Helicoverpa zea (Boddie) and Heliothis virescens (Fabricius) has not been reported. We now report the effect of gossypol and gossypolone fed to first instar of H. zea at 0.06%, 0.08% and 0.12% in an artificial diet.  Pupae from larvae fed 0.12% gossypolone were significantly smaller than those fed the control diet or any of the diets with gossypol.  Gossypol at the concentrations tested did not extend days-to-pupation, but in an earlier study gossypol at 0.16% extended days-to-pupation from 13.9 days (± 0.5) to 22.6 days (± 1.0).  In this study, gossypolone was found to extend days-to-pupation at a lower concentration.  That is, gossypolone at 0.12% extended days-to pupation from 13.3 days (± 0.1) for the control to 20.8 days (± 0.7)]. A delay in days-to-pupation will reduce the number of generations that develop during a growing season, and may reduce larval survival.  Thus, increasing expression of a single gene that could enhance formation of gossypolone may provide an overall increase in resistance to Heliothines in cotton plants.