Parasitization of Lepidopterous Pests on Fresh Market Tomatoes in Southern California

Abstract

Immature stages of the major lepidopterous pests of tomatoes were sampled from summer and fall plantings grown in the absence of insecticides and held in the laboratory to determine levels of parasitization and species of parasites associated with each host. Nine species of parasites were reared from Heliothis zea (Boddie), 13 from Trichoplusia ni (Hubner), 14 from Spodoptera exigua (Hubner), and 2 species from Manduca sexta (L.). Mean parasitization of H. zea larvae ranged from 72.5% in 1965 to 89.5% in 1967; that for T. ni from 51.4% in 1965 to 70.5% in 1966; that for S. exigua from 24.1% in 1979 to 83.9% in 1967; and that for M. sexta from 0.0% in 1967 to 14.1% in 1966. Parasitization of H. zea, T. ni . and M. sexta eggs ranged from 51.4, 24.6, and 41.9%, respectively, in 1967 to 55.7, 53.4, and 49.5% in ]966. Hyposoter exiguae Viereck and Trichogramma pretiosum Riley were the most common larval and egg parasite, respectively, reared from all four pest species.