AN EVALUATION OF SELECTIVE HELICOVERPA-ARMIGERA CONTROL OPTIONS IN SWEET CORN

Helicoverpa armigera is a serious insect pest of sweet corn in Austral ia and is becoming increasingly difficult to manage with conventional chemical insecticides due to resistance problems. A number of alternat ive H. armigera control options were evaluated in sweet corn and compa red with deltamethrin and no action (control). The alternative tactics evaluated were: heliothis nuclear polyhedrosis virus plus Trichogramm a nr. brassicae releases; Bacillus thuringiensis; and Trichogramma alo ne. The H. tea nuclear polyhedrosis virus + Trichogramma plots had the lowest cob damage (6.0%), followed by the B. thuringiensis plots (12. 0%), Trichogramma alone plots (20.2%), control plots (23.2%) and delta methrin plots (53.5%). There was no evidence to suggest that the Trich ogramma nr. brassicae releases had any impact on H. armigera egg morta lity. However, there was a large natural population of Trichogramma pr etiosum in all plots. The application of deltamethrin reduced the acti on of these wasps and predators, resulting in higher larval infestatio n and significantly more cob damage. The findings indicate that the pa thogens heliothis nuclear polyhedrosis virus and B. thuringiensis can effectively control H. armigera when their action complements high nat ural levels of egg parasitism, and that they have potential for use in integrated pest management programs in sweet corn.