Insecticidal Activity of Pyridalyl: Acute and Sub-Acute Symptoms in Spodoptera litura Larvae

Abstract

The insecticidal action of pyridalyl at various dosages against S. litura larva was observed. Larvae treated with 100 ng/larva and higher dosages were killed within 6 hr without any conspicuous symptoms. In contrast, larvae treated with 25 ng/larva and lower dosages showed unique symptoms similar to scar burns at the site treated with pyridalyl after molting. Such symptoms caused interference with metamorphosis, suggesting that pyridalyl would suppress populations of S. litura even at lower dose rates. Taking such unique insecticidal symptoms into consideration, it is suspected that pyridalyl has a novel biochemical mode of action. © Pesticide Science Society of Japan