Ascorbic acid influences the development and immunocompetence of larval Heliothis virescens

Abstract

AbstractAscorbic acid, known to be a free radical scavenger and vital to insect development, is important in larval resistance to baculovirus infection. We sequentially elevated the ascorbic acid content in an ascorbic acid‐depleted diet and evaluated the effect on larval Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) development and immunocompetence. Dietary ascorbic acid levels lower than 0.7 g l−1 slowed the growth rate of larvae, reduced pupal weights significantly, and severely inhibited adult emergence. Larvae developing on ascorbic acid‐free diet experienced far higher levels of mortality following per os infection with virus. 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 control levels of ascorbic acid. These results demonstrate an indirect correlation between the level of ascorbic acid in the food stream of larval H. virescens and the susceptibility of the insect to baculoviral infection.