Colonization and Resurgence of Insect Pests of Soybean in Response to Insecticides and Field Isolation1

Abstract

Treatment of soybean with methyl parathion and methomyl caused resurgence of populations of Plathypena scabra F., Heliothis spp., Pseudoplusia includens (Walker), Anticarsia gemmatalis Hübner, and Epilachna varivestis Mulsant. Less resurgence occurred when monocrotophos was applied. Removal of the natural biotic agents by the insecticides was probably the major reason for the resurgence. Newly-established soybean fields in isolated situations were more susceptible to outbreaks of these pests than fields which were cultivated annually.