Movement of a nuclear polyhedrosis virus from soil to soybean and transmission in Anticarsia gemmatalis (Hubner) (Lepidoptera: Noctuidae) populations on soybean

Bioassay of soil to which A. gemmatalis nuclear polyhedrosis virus (NPV) had been applied showed that viral activity was reduced during the summer, but much of the virus remained active. Viral activity in the upper layer of soil was generally greater following tillage, and the level of virus activity on plants was related to the concentration of NPV applied to the soil at planting. Tillage and rainfall resulted in increased mortality of larvae fed leaflets from low on the plant, but not from high on the plant. An epizootic developed in a field experiment only after rainfall.