BENZOYLPHENYL UREAS EFFECT ON GROWTH AND DEVELOPMENT OF EULOPHUS-PENNICORNIS (HYMENOPTERA, EULOPHIDAE), A LARVAL ECTOPARASITE OF THE CABBAGE MOTH (LEPIDOPTERA, NOCTUIDAE)

The hymenopteran parasitic wasp, Eulophus pennicornis, shows promise f or controlling Mamestra brassicae. The effect of the benzoylphenyl ure as diflubenzuron, hexaflumuron, and teflubenzuron was examined by feed ing treated cabbage leaves to host caterpillars, by topical applicatio n, or by spraying the caterpillars. Development of the parasitic wasp on caterpillars treated with benzoylphenyl ureas was affected in a con centration-dependent manner. The highest effect occurred in the early larval stadia. After feeding treated cabbage leaves to caterpillars, h exaflumuron was tile most toxic compound followed by teflubenzuron and diflubenzuron. The lowest concentration (0.05 mu g [AI] per caterpill ar) of hexaflumuron teflubenzuron: and diflubenzuron, applied topicall y to a M. brassicae caterpillar resulted in 10, 45, and 59%, respectiv ely, normal E. pennicornis adults. Spraying diflubenzuron at a concent ration of 6.4 mg (AI)/liter on the host caterpillar caused 30% mortali ty in E. pennicornis larvae compared with 94% for teflubenzuron and 99 % for hexaflumuron al a concentration of 3.4 and 12.7 mg (AI)/liter, r espectively. Female parasites did not suffer significant mortality by contact with the chemicals, but there was up to 70% reduction of proge ny formation at a concentration of 38.1 mg (AI)/liter for hexaflumuron or 10.2 mg (AI)/liter for teflubenzuron. These results indicated that the use of chitin synthesis inhibitors at recommended doses may inhib it the development of the parasite.