Toxicity of cypermethrin and enzyme inhibitor synergists in red hairy caterpillar Amsacta albistriga (Lepidoptera: Arctiidae)

Abstract

Background: The frequent usage of broad-spectrum insecticides like cypermethrin in agriculture activities could lead to the development of resistance in insects like Amsacta albistriga. Objectives: The present study was conducted to understand the toxicity of cypermethrin with and without a combination of three enzyme inhibitors (PBO, DEM, and TPP) on A. albistriga using a topical bioassay. Methodology: The in vitro and in vivo studies were conducted to understand the effect of three enzyme inhibitors such as piperonyl butoxide (PBO) and diethyl maleate (DEM) and triphenyl phosphate along with six different concentration of cypermethrin on the activities of acetylcholinesterase (AChE), esterase (EST), glutathione S-transferase (GST), and mixed-function oxidase (MFO) of A. albistriga. Results: Bioassay shows elevated LC50 for cypermethrin (63.32 ppm) whereas in a combination of PBO cypermethrin LC50 values were reduced into 12.039 ppm followed by TPP combination as 13.234 ppm. In vitro and in vivo inhibition analysis shows AChE inhibition by PBO P < 0.01, esterase inhibition by PBO, and TPP were less; GST inhibition by DEM was observed at P < 0.001. Native PAGE results revealed that the in vitro AChE isoenzyme inhibition could be possible by PBO synergism with cypermethrin in A. albistriga. Conclusions: The overall results conclude that the PBO and TPP enzyme inhibitors could be fine synergist molecules when it mixed with cypermethrin insecticide to control and manage the insecticide-resistant Amsacta albistriga in the field.