AN ANALYSIS OF THE NATURAL BIOLOGICAL CONTROL OF TRICHOPLUSIA NI (LEPIDOPTERA: NOCTUIDAE) ON COTTON IN CALIFORNIA

Abstract

The impact of natural enemies on Trichoplusia ni (Hübner) is reviewed. Disappearance of eggs and small larvae (presumably due to predation) is consistently the major intrageneration mortality. Parasitoids and a nuclear polyhedrosis virus effect mortality of larvae surviving early-instar predation. From the analysis, it is argued that natural enemies capable of effective colonization of the habitat and rapid exploitation of the prey population (i.e., r-strategists) are suitable agents for biological control of pests of annual or short-cycle crops. Polyembryony, polyphagy, and polyhedrosis represent attributes which enable the particular natural enemy to implement the rapid-host-exploitation strategy. This interpretation gives added theoretical support for importation of exotic natural enemies of pests of non-perennial crop plants.