Abstract: Experiments conducted to study the effect of various adjuvants on the larval mortality of Helicoverpa armigera NPV under simulated sunlight revealed that all the adjuvants (either alone or in combination) resulted in significantly higher larval mortality as compared to the virus alone. A combination of three adjuvants, viz., molasses (5.0%) + Tinopal (0.2%) + lampblack (0.1%) showed the highest larval mortality (94.2%) under simulated sunlight with the lowest LT50 values (99.6 h). It was also observed that the persistence of HearNPV was higher when molasses (5.0%) + Tinopal (0.2%) + lampblack (0.1%) was used as adjuvant with an OAR (original activity remaining) of 86 and 36.2% after 1 and 6 days after treatment, respectively under open weather conditions on tomato plants.