Efficacy of six dry formulations of insecticides against five major stored-product insect species
Abstract: Six newly developed dry insecticide formulations containing pirimiphos-methyl and deltamethrin were loaded onto licocene, a waxy material used as a filler, to decrease the recommended application dosages of these insecticides. Out of the six formulations, three were formulated with diatomaceous earth as an inert ingredient and three without. Formulations A, B, E, and F containing pirimiphos-methyl (0.5 ppm) and deltamethrin (0.12 or 0.24 ppm) were applied to corn, whereas formulations C and D containing only deltamethrin (0.24 ppm) were applied to both corn and wheat. Adults of the red flour beetle, sawtoothed grain beetle, rice weevil, lesser grain borer, and eggs of Indian meal moth were exposed to untreated and treated grain at 28 °C and 65% RH. All adults of the beetle species died after a 7- and 14-day exposure and no progeny were produced on insecticide-treated grain. Live larvae and adults were observed on untreated grain and no larvae or adults were found in all formulations except formulations D and E. All formulations performed well against the beetle species and the Indian meal moth, and have potential as candidate grain protectants.