EFFECTS OF COMBINATIONS OF CHLORPYRIFOS AND CYPERMETHRIN ON MORTALITYOF CORN-EARWORM AND FALL ARMYWORM (LEPIDOPTERA, NOCTUIDAE) LARVAE

Mixtures of chlorpyrifos and cypermethrin were tested against 1-day-ol d larvae of corn earworm, Helicoverpa tea (Boddie), and fall armyworm, Spodoptera frugiperda (J.E. Smith), to determine the type of joint ac tion involved in insect mortality. Statistical analyses indicated that mixtures of both insecticides interacted additively in both species. Chlorpyrifos alone was not as effective against larvae of fall armywor m as it was against larvae of corn earworm. No apparent differences in toxicity between the two species were observed with cypermethrin.