Location: Biological Control of Insects Research
Title: Impact of Ascorbic Acid Fortification on the Effectiveness of Biological Control Agents Authors
Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 10, 2009
Publication Date: November 19, 2008
Citation: Coudron, T.A., Popham, H.J., Shelby, K. 2008. Impact of Ascorbic Acid Fortification on the Effectiveness of Biological Control Agents [abstract]. Entomological Society of America Annual Meeting. p.134. Technical Abstract: Recent developments in genetic engineering have paved the way for researchers to produce crops of high nutritional and yield value, in addition to being resistant to diseases and pests. Ascorbic acid content is one of the nutritive parameters researchers are trying to enhance in plants. This study investigated the effect of altering dietary ascorbic acid concentrations in the host larvae of a beneficial wasp, Euplectrus comstockii Howard (Hymenoptera: Eulophidae) and a baculovirus AcMNPV. Life history parameters of the wasp and infection rates of the virus were measured when larval Heliothis virescens reared on diets varying in ascorbic acid concentrations served as the host. Odds and odds ratio analyses showed that the probability of egg hatch and adult emergence for the wasp increased with the amount of ascorbic acid in the diet of the host, and that the rate of development and probability of female or male progeny, was similar for most levels of ascorbic acid tested. Larvae reared on ascorbic acid deficient diet experienced far higher levels of mortality following per os infection with AcMNPV. A viral dose causing 85% mortality in larvae reared on ascorbic acid-free diet caused 40% mortality in larvae fed diet supplemented with ascorbic acid. Additionally, viral infection in larvae fed an ascorbic acid-free diet, as monitored by epifluorescence microscopy, showed signs of infection much earlier than larvae fed diet supplemented with ascorbic acid. Collectively, this would indicate that as the ascorbic acid concentration is increased in the pest insect (and perhaps as the ascorbic acid concentration in the plant is increased) the effectiveness of microbial pathogens would decrease, but the effectiveness of the wasp is likely to increase.