Field Evaluation of Formulations of Nuclear Polyhedrosis Virus Against the Cotton Bollworm, Helicoverpa armigera

Abstract

Formulations of nuclear polyhedrosis virus were field experimented against the cotton bollworm, Helicoverpa armigera in comparison to chemical insecticide and insect growth regulator. Evaluations were based on total number of bollworms found on cotton 2 days after insecticide application and weight of seed cotton harvested through out the planting season. Results form the experiments in 1990, 1991 and 1992 indicated that most virus formulations significantly reduced bollworm population better than chemical insecticide and insect growth regulator. Some virus formulations provided higher seed cotton than chemical insecticide. Yields obtained from several other formulations were not significantly different from that obtained with chemical insecticide and insect growth regulator. Among formulations of virus tested, those that contained freeze-dried virus powder were more effective than virus suspension. Results from this study suggested that the most effective virus formulation against the cotton bollworm should contain carbon powder or Sunguard®, yeast extract or molasses, corn powder or cotton seed powder, soybean oil or corn oil, Guar Gum® and Triton® CS-7. All these additives were necessary for the enhancement of virus efficacy and persistence in cotton field.