PROBLEMS ASSOCIATED WITH THE USE OF ARTHROPOD VIRUSES IN PEST CONTROl

Abstract

Over 700 species of insects and mites are reported to have viral diseases ( 15). More than 320 viruses have been isolated from over 250 insect and mite species of agricultural importance. At least 38 arthropod species have been examined in terms of control with arthropod viruses. The production of arthropod viruses from 5 insect species has been industrialized on a pilot basis by private enterprise in the United States (9). Most of the species investigated for control with arthropod viruses are important pests of food, fiber, and forest crops in the world. Represented are species for which large amounts of pesticides are currently used and which plant protection specialists have the greatest difficulty controlling. In the state of California, the combination of estimated damage and crop losses caused by species in this category (bollworm, armyworm, looper, cutworm, gelechiid moths, leafroller moths, codling moth, and citrus red mite) amounted to over $73 million in 1970 (53). The status, characterization, nomenclature, and classification of arthropod viruses was recently reviewed (15). Thus far, arthropod viruses are represented by six genera, namely, Baculovirus (nuclear polyhedrosis and granulosis viruses), Pox­ virus (Entomopoxviruses), Iridiovirus, Parvovirus (Densonucleosis viruses), En­ terovirus, and Rhabdovirus; one group, cytoplasmic polyhedroses; and many unclassified viruses. The species of Baculovirus are the best known arthropod viruses and some have been used for pest control on a commercial basis (9). During the 1950s, alfalfa growers in California collected and utilized nuclear polyhedrosis virus (NPV) to control the alfalfa caterpillar (Colias eurytheme) (48). For many years growers and pest control operators in various parts of the United States have field collected and utilized NPV for the control of the cabbage looper ( Trichoplusia ni) on a variety of food crops (73). Spodoptera NPV has been utilized on a limited scale in California