Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2001
Publication Date: 2/20/2002
Citation: BEHLE, R.W., DOWD, P.F., TAMEZ-GUERRA, P., LAGRIMINA, L.M. EFFECT OF TRANSGENIC PLANTS (OVER)EXPRESSING TOBACCO ANIONIC PEROXIDASE ON THE TOXICITY OF ANAGRAPHA FALCIFERA NUCLEOPOLYHEDROVIRUS TO HELICOVERPA ZEA BODDIE (LEPIDOPTERA:NOCTUIDAE). JOURNAL OF ECONOMIC ENTOMOLOGY. 2002. v. 95(1). p. 81-88. Interpretive Summary: Insects cause hundreds of millions of dollars of damage to crops in the United States each year. Insect damage in corn, cotton, and peanuts frequently increases the levels of ear mold toxins, which limits acceptability of the products both within the United States and for export. Often combinations of different insect control strategies can provide the most effective, economical, and environmentally acceptable insect management in different crops. However, the compatibility of these control measures, especially with those that include biotechnologically improved crop varieties, has received only limited study. Our laboratory studies demonstrated that the efficacy of corn earworm biological control by a naturally occurring insect disease was not adversely affected by the enhanced production of a protein (peroxidase) introduced by biotechnological means in tobacco and tomato plants that reduced insect damage. These studies indicate two diverse biological control techniques can be effectively combined to produce more effective insect management that is potentially economical and environmentally compatible. Potential benefits include greater profits for farmers and improved food quality for consumers.
Technical Abstract: Wild-type, and corresponding transgenic tomato (Lycopersicon esculentum Miller), and two tobacco (Nicotiana spp.) plants that (over)express a tobacco anionic peroxidase were used as a source of leaf disks to compare the susceptibility of neonate corn earworms [Helicoverpa zea (Boddie)] to a strain of the baculovirus Anagrapha falcifera nucleopolyhedrovirus. Transgenic plants expressed approximately 5- to over 400-fold higher peroxidase than corresponding tissues of wild-type plants. The H. zea larvae typically fed 1.5- to 2-fold less on transgenic compared to wild-type leaf disks. There was only one experiment (with tomato leaves) where the larvae fed on transgenic leaves were less susceptible to the virus based on nonoverlapping 95% confidence intervals for calculated LC(50)s. When the exposure dose was corrected for reduced feeding on the transgenic leaf disks, the insecticidal activity of the virus was not significantly different for larvae fed on transgenic vs. wild- type plants. Eight other experiments (with two species of tobacco and tomato) indicated either no significant effect or enhanced susceptibility to the virus of larvae fed on the transgenic leaves. These results indicate enhanced insect resistance in plants (over)expressing a specific anionic peroxidase may be compatible with applications of AfMNPV. Potential reasons for this compatibility are discussed.