Survival of the 1stand 3rd instars of Kansas Dipel-resistant and -susceptible European corn borer, Ostrinia nubilalis , fed different parts of whorl stage transgenic Bt corn plants was investigated in the laboratory. All first instars of resistant and susceptible strains died after 3 days of infestation on all tested Bt corn tissues. Percent survival of 3rd instars of the resistant strain fed fully expanded leaves, partially expanded leaves, leaf sheaths, and stalk tissues of the Bt corn plants was 33, 35, 27, and 24%, respectively, after 3 days of infestation. After 5 days, the survival was reduced to 13, 23.5, 6.7, and 17.7%, and by the 10th day no survivors were observed. Survival of the first instars of both strains ranged from 69 to 90% on all tested non-Bt corn tissues, and no differences were observed between resistant and susceptible strains. After 3 days of infestation, the relative damage caused by 30 first instars of the resistant strain to fully expanded leaves, partially expanded leaves, and leaf sheaths of the Bt corn plants was 0.08, 0.12, and 1.1%, respectively. For the susceptible strain, the corresponding relative damage reached 0.01, 0.06, and 0.35%. The number of the pinholes on Bt corn stalks made by first instars averaged 5.3 for the resistant strain and 2.7 for the susceptible strain. The relative damage of 30 resistant or susceptible first instars on non-Bt corn tissues ranged from 32.7 to 52%, and 23 to 37 pinholes. After 3 days of infestation, the relative damage of 10 resistant 3rd instars on fully expanded leaves, partially expanded leaves, and leaf sheaths of the Bt corn reached 25, 30, and 20%, respectively. Damaged areas within Bt corn stalks caused by the 3rd instars were larger than those caused by 1st instars.
Species 1: Lepidoptera Crambidae Ostrinia nubilalis (European corn borer)
Keywords: Transgenic Bt corn, Bt resistance
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA