BINARY ACTION OF CHLORPYRIFOS-METHYL AND METHOPRENE ON THE LARVAL BIOCHEMISTRY OF ALMOND MOTH, EPHESTIA CAUTELLA WALKER (LEPIDOPTERA:PYRALIDAE)

Abstract

Sub-lethal concentrations i.e. 1, 2 and 4 ppm mixture of chlorpyrifos-methyl and methoprene in the ratio of 9:1 caused a significantly dose-dependent reduction in the levels of total protein, DNA, RNA and RNA/ DNA ratio and a significantly dose-dependent enhancement in the total free amino acid levels in haemolymph and fat body tissues of the larva of almond moth, Ephestia cautella Walker, a serious pest of stored cereals. The highest concentration ( 4ppm ) of this mixture caused abrupt changes in the metabolic framework of the larva that impairs its physiological fitness, which ultimately leads to death, if exposed to 8ppm concentration of this binary mixture. The present study states that methoprene enhances the toxicodynamic property of chlorpyrifos-methyl in a synergistic way.