1ST-GENERATION PARASITISM OF THE MIMOSA WEBWORM (LEPIDOPTERA, PLUTELLIDAE) BY ELASMUS-ALBIZZIAE (HYMENOPTERA, EULOPHIDAE) IN AN URBAN FOREST

Elasmus albizziae Burks is a parasitoid of the mimosa webworm, Homadaula anisocentra Meyrick. Honeylocust foliage samples containing first-generation mimosa webworm cocoons were collected in Ames, Iowa, by using a stratified random sampling plan during 1985, 1986, and 1987. Survey objectives were to determine the percentage of parasitized first-generation webworm prepupae and to assess the potential of E. Albizziae in an integrated pest management program. Conservative determinations of first-generation parasitism of mimosa webworm prepupae by E. Albizziae were 44,39, and 47% for 1985, 1986, and 1987, respectively. Precise effects of this parasitism on webworm populations have not been determined. Mortality levels imposed by E. Albizziae should, however, be taken into account when management practices are considered. The parasitoids are exposed during host-seeking activity and would be vulnerable to broad-spectrum insecticides applied when first-generation webworm larvae were spinning cocoons on honeylocust foliage. When insecticidal treatment is warranted for management, it is recommended that Bacillus thuringiensis insecticides be adopted as the treatment of choice over broad-spectrum insecticides to minimize damage to the parasitoid complex. © 1990 Entomological Society of America.