Effects of plant identity and chemical constituents on the efficacy of a baculovirus against Heliothis virescens

Baculoviruses are anhropod-specific, dsDNA viruses primarily used to control lepidopteran pests. A limitation of the use of baculoviruses for pest control is that their efficacy is modifiable by host-plant chemicals. The levels of phenolic substrates and two foliar oxidative enzymes, peroxidase (POD) and polyphenol oxiclase (PTO), were significant predictors of disease caused by a baculovirus in Heliothis virescens fed on either cotton or lettuce; POD was the more influential of the two enzymes. The higher the plant phenolase activity, the lower the percent mortality and the slower the insects died from vital infection. Whether a particular class of phenolic substrates was correlated with enhanced or attenuated baculoviral disease depended upon context, i.e., admixture. Diminution of viral efficacy by plant oxidative activity may compromise the compatibility of baculoviruses with other components of an integrated pest management system such as host plant resistance.