Competition Between Trichogramma pretiosum1 and Orius insidiosus2 for Caged Tobacco Budworms 3 on Cotton Treated with Chlordimeform Sprays 4

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Abstract
The hemipteran predator, Orius insidiosus (Say) plus sprays of chlordimeform [ N ′-(4- chloro- o -tolyl)- N , N -dimethylformamidine] reduced the effect of Trichogramma pretiosum Riley on a caged population of the tobacco budworm, Heliothis virescens (F.). The predator consumed both parasitized and unparasitized tobacco budworm eggs and fed readily on young larvae. The sprays decreased the viability of tobacco budworm eggs, influenced the fecundity of the adult budworms, and reduced emergence of adult T. pretiosum from parasitized eggs, but they did not directly affect O. insidiosus . The combination of spray, parasites, and predators prevented populations of tobacco budworm larvae from exceeding 2400/acre for ca. 2 months. Although T. pretiosum parasitized relatively large numbers of tobacco budworm eggs when the density of O. insidiosus was low and chlordimeform sprays were not bemg applied, the predator had more effects on the tobacco budworm than the parasite through most of the test period. However, when the population of the cotton leafperforator, Bacculatrix thurberiella Busck, was reduced with chlordimeform, the population of O. insidiosus declined steadily despite a relatively high density of tobacco budworms. The population of cotton leafperforators, therefore, appeared to have great mfluence on the population of O. insidiosus .

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