EXPERIMENTS WITH A VIRUS DISEASE OF THE COTTON BOLLWORM HELIOTHIS ARMIGERA (HBN.)

Laboratory tests with a nuclear polyhedral virus disease of Heliothis armigera indicated that it was more infective and had a shorter incubation period in the younger instars than in the older larvae. Larvae on cotton plants sprayed with an aqueous suspension of the virus became infected; mortality depended on the number of polyhedra applied to the plant irrespective of the concentration in the suspension. Spraying with the virus seems unlikely to control bollworm in Uganda, but might do so where it is not already endemic and where bollworm numbers fluctuate more during the year.