Monitoring Helicoverpa zea Susceptibility to Bt Toxins: Results of 2008 Studies

Susceptibility of  bollworm, Helicoverpa zea (Boddie) field populations collected on different host plants from U.S. Cotton Belt states to Bt toxins in diet assays and to excised Bt plant tissues were measured  at the University of Arkansas in 2008 season.  Neonate were exposed to diagnostic concentrations of Cry1Ac, Cry2Ab2, Vip3A insecticidal toxins in diet incorporated assays and to Cry1F on diet overlay assays.  For plant bioassays, neonates were fed excised leaves, squares and bolls from Bollgard, Bollgard II and Widestrike cottons until death or pupation. Results will be discussed.