Comparative efficacy of two bio-insecticides in the fight against Helicoverpa armigera (Hubner, 1808) (Lepidoptera: Noctuidae) pest of crops

Abstract

Among the tomato pests, Helicoverpa armigera causes significant damage to the crop. Chemical control is the most commonly used method against this pest and is becoming less and less effective. In order to find out an alternative, a formulation of Helicoverpa armigera nucleopolyhdrovirus (HearNPV) of 0.15% was compared to a 2% neem extract product in the laboratory to assess its potential role as a bio-insecticide on the pest. The formulations were tested on stage 2 (L2) larvae up to stage 5 (L5). Results showed 100% mortality with HearNPV formulation compared to 71.48% with neem formulation with a highly significant difference (p-0.0001) 6 days after treatment in L2/L3 larvae and 87.92% versus 70.74% 15 days after treatment in L4/L5 larvae. An average lethal time (LT50) that varies from treatment to treatment has been observed in L4/L5. This TL50 is reduced in L2/L3 and is shorter with neem. These results show that HearNPV formulation appears to be more effective than neem formulation with faster action on young larvae.