Reaction of Five Species of Soybean Caterpillars to Attack, by the Predator, Podisus maculiventris 1

Abstract

Larvae of 5 species of Lepidoptera known to attack soybeans were exposed on greenhouse-grown soybean plants to 5th-instar nymphs of the spined soldier bug, Podisus maculiventris (Say), to evaluate the influence of larval behavior on the ability of this predator to kill its potential prey. Species tested included the corn earworm, Heliothis zea (Boddie), the cabbage looper, Trichoplusia ni (Hubner), the soybean looper, Pseudoplusia includens (Walker), the velvetbean caterpillar, Anticarsia gemmatalis Hubner, and the green cloverworm, Plathypena scabra (F.). Differences in larval behavior among the species had no significant effect on the ability of the predator to contact a larva with its proboscis, though the approach behavior and the time required to make contact varied. However, once contact was made, behavior of the prey larvae significantly affected the ability of the predator to subdue them. Anticarsia gemmatalis and Plathypena scabra reacted most vigorously to attack and suffered the least mortality (ca. 20–35%). Trichoplusia ni and Pseudoplusia includens offered the least resistance and were killed most frequently (ca. 75–80%). Resistance by H. zea and its mortality (ca. 60%) were intermediate. Pest management programs involving releases of Podisus macuiventris should regard the species composition of a pest population as a critical variable.