Effect of Insecticides for Controlling Corn Insect Pests on the Predaceous Earwig, Prereus simulans Stallen

Abstract

The test of insecticides fo rcontrolling corn insect pests on the predaceous earwig, Proreus simulans Stallen was conducted at National Corn and Sorghum Research Centre, Nakornratsema province during October 1989 - January 1990. The percentage mortality of earwig was determined at 10 days after application of insecticides.
It was found that carbofuran and turbufos, a carbamate and organophosphate insecticides, provided the highest toxicity level with 78.93 and 66.34 percent mortality of earwigs at 10 days after topical application.
The medium toxicity levels were organophosphate insecticides, EPN, EPN + mryhly pstsyhion snf dulptogod, ehivh ptobifrf 51.58, 44.69 and 34.11 percent mortality of earwigs respectively, at 10 dkays after spray.
It can be concluded that the organophosphate insecticides provided more toxicity to earwigs than the other groups and the topical application method was also showed higher toxicity than spraying method. It is possibly due to the direct contact ability to those insecticides. The effect of insecticides on increasing the earwig population were also investigated at 30 days afterapplication. The result showed that the organophosphate insecticides provided the highest increasing rate of 0.88 - 1.89 folds while the control plot showed the increasing rate of 2.21 folds.