Intra- and inter-specific effects of cotton, soybean and clover on the survival time, yield and infectivity of occlusion bodies (OBs) of the Helicoverpa zea nucleopolyhedrovirus (HzNPV) in infected heliothine, Helicoverpa zea (Boddie) and Heliothis virescens (F.), larvae were studied. Survival time of HzNPV-infected H. zea fed on vegetative tissues of clover was significantly higher than on reproductive tissues. Across host plants, survival time of H. zea on both vegetative and reproductive tissues differed significantly in the order of clover>cotton>soybean. Survival time on cotton of HzNPV-infected H. virescens fed on vegetative tissues was also significantly higher than on reproductive tissues. Across host plants, survival time of larvae on vegetative tissues differed significantly in the order of cotton>soybean>clover. Helicoverpa zea or H. virescens larvae fed on vegetative tissues produced significantly more OBs than those larvae fed on reproductive tissues of cotton and soybean. Helicoverpa zea larvae fed on reproductive tissues of cotton produced significantly less OBs than those fed on reproductive tissues of soybean or clover. OBs produced by H. virescens fed vegetative tissues of host plants also differed significantly in the order of soybean>clover>cotton. LC₅₀ values for H. virescens larvae fed HzNPV were higher when the virus was produced in larvae fed on reproductive tissues than on vegetative tissues on all host plants. OBs produced by H. zea or H. virescens larvae fed on reproductive tissues were less infectious as compared to OBs produced on vegetative tissues in all host plants, except H. zea on cotton. This reduction in infectivity of OBs in larvae fed on reproductive tissues was most prominent in H. virescens on cotton, followed by soybean and clover. In conclusion, survival time, viral production and viral infectivity in heliothine larvae were affected by both tissue and plant species.