Effects of Helicoverpa armigera Nucleopolyhedrosis Virus (HaNPV) on the Larvae of the Diamondback Moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Laboratory studies were performed to determine the insecticidal activity of baculovirus against diamondback moth, Plutella xylostella. The nucleopolyhedrosis (HaNPV) was tested against 2nd instar larvae fed on cabbage leaf disks treated with aqueous suspensions of occlusion bodies (OB). Lethal concentrations values (LC25, LC50, and LC75) were 2.2 x 10E3, 3.8 x 10E4, and 6.6 x 10E5 PIB/ml for 2nd larval instars, respectively. Median lethal time (LT50) to similar response levels (mortality rates 50-75%) decreased with decreasing larval age (from 114.23 to 106.05 h). Larval development time and pupal weight were not affected by different concentrations (LC25, LC50, and LC75) of HaNPV. Significant differences were found in the pupal rate and adult emergence in larvae treated by different concentrations. In conclusion, HaNPV treatment failed to cause high mortality rates in P. xylostella larvae, but it had prompt deleterious effects on survivor's development and emergence.