Susceptibility of Anticarsia gemmatalis (Lepidoptera: Noctuidae), Reared on Four Host Plants, to a Nuclear Polyhedrosis Virus

Median lethal doses (LD 50 s) of Anticarsia gemmatalis nuclear polyhedrosis virus (AgNPV) were determined in 3rd-instar velvetbean caterpillars, Anticarsia gemmatalis Hübner, reared on 4 host plants. The LD 50 s were 22.3, 35.2, 14.6, and 41.0 occlusion bodies per insect in A. gemmatalis reared on Glycine max (L.) Merrill, Pueraria lobata (Willd.) Ohwi, Rhynchosia minima (L.) DC, and Vigna luteola (Jacq.) Benth, respectively. Based on lack of overlap of 95% CLs, the insects reared on V. luteola were less susceptible to the virus than those reared on G. max or R. minima . Mean larval development time of velvetbean caterpillar reared on P. lobata was significantly longer than for insects reared on the other 3 plants. The pupal weights of velvetbean caterpillar reared on G. max and V. luteola were significantly greater than those of insects reared on R. minima and P. lobata . Larval development times and pupal weights of the survivors of virus treatments were not significantly different from those of controls reared on the 4 plants. The percentages of larvae pupating for insects that survived exposure to AgNPV were similar to those for controls. However, insects surviving AgNPV exposure had a higher percentage of deformed pupae than control insects. Thus, host plant suitability did not affect susceptibility to AgNPV, and the primary sublethal effect on survivors of viral treatment was an increase in the percentage of pupae deformed.