FIELD-EVALUATION OF INSECT RESISTANCE IN A WILD TOMATO AND ITS EFFECTS ON INSECT PARASITOIDS

Populations of Helicoverpa (=Heliothis) tea (Boddie), Heliothis viresc ens (F.), Manduca sexta (L.) and M. quinquemaculata (Haw.) and their e gg and larval parasitoids were sampled in field plots of the: insect-r esistant wild tomato, Lycopersicon hirsutum f. glabratum C. H. Mull, a ccession PI 134417; susceptible commercial tomato cultivar 'Better Boy '; F-1 hybrid; and selected, moderately resistant backcross genotype. Densities of H. zea and H. virescens eggs and small larvae were higher on resistant genotypes than on susceptible genotypes, but densities o f large larvae were similar on all genotypes. Densities of Manduca spp . larvae were too low to permit similar analyses of the effects of pla nt genotype. Rates of egg parasitism by Trichogramma spp. and Telenomu s sphingis (Ashmead) were reduced on insect-resistant genotypes. Rates of parasitism by the larval parasitoids Campoletis sonorensis (Camero n) and Cotesia congregata (Say) were reduced on resistant genotypes. N o consistent effects on parasitism rates by Cotesia marginiventris (Cr esson) were observed and parasitism rates by Cardiochiles nigriceps Vi ereck were unaffected.