Survival and Feeding of African Bollworm, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) Affected by Neem, Azadirachta indica (A. Juss) Extracts

The effects of neem oil (Nimbecidine 0.03% Aza) and water extracts of neem seed and leaf on African bollworm, Helicoverpa armigera were studied each at three concentration levels (2.5%, 5% and 10%) under laboratory condition. Square dip and larval immersion experiments were conducted using Completely Randomized Design in three replications. In square dip experiment, high mortalities were statistically recorded from larvae treated with all concentration levels of seed extract and the two lower concentration levels of leaf extracts as compared to mortalities from control larvae. In larval immersion experiment, high mortalities were obtained from larvae treated with high concentration levels of both seed and leaf extracts as compared to control larvae. Three days after treatment application, significantly low numbers of squares were damaged by the larvae treated with the three concentration levels of seed extracts as compared to the control. Significant feeding reductions on artificial diet were also observed from larvae treated with various concentration levels of Nimbecidine, seed and leaf extracts at 6 and 9 days after treatment application in larval immersion experiment. Generally, neem extracts from the seed and leaf and neem oil (Nimbecidine) have significant negative effect on the survival and feeding of Helicoverpa armigera larvae.