TALL OIL - ENHANCEMENT OF NEEM AND AZADIRACHTIN TOXICITY TO THE VARIEGATED CUTWORM, PERIDROMA-SAUCIA HUBNER (LEP, NOCTUIDAE)

Potentiation of the insecticidal activity of neem and its active princ iple, azadirachtin, by depitched tall oil was examined in experiments with the variegated cutworm, Peridroma saucia Hiibner. Contact toxicit y of both neem and azadirachtin to P. saucia was enhanced more than 2 fold when formulated in combination with depitched tall oil, compared to that with the insecticides alone. Nutritional analyses of fourth in star larvae following topical application of neem or azadirachtin in c ombination with depitched tall oil demonstrated stronger inhibition in larval growth, diet consumption, and dietary utilization than when th e test materials were administered alone. These results suggest that t he oil enhances the bioavailability of azadirachtin to target tissues or receptors in the insect. Depitched tall oil also enhanced the antif eedant effect and residual action of neem and azadirachtin on cabbage plants to P. saucia larvae.