Effects of Translaminar versus Conventional Insecticides on Liriomyza huidobrensis (Diptera: Agromyzidae) and Diglyphus isaea (Hymenoptera: Eulophidae) Populations in Celery

Field trials compared the effects of 2 translaminar insecticides (abamectin and cyromazine) and 3 nontranslaminar insecticides (cypermethrin, methomyl, methamidophos) for control of Liriomyza huidobrensis (Blanchard) and their effect on Diglyphus isaea Walker in celery ( Apium graveolens L.). Abamectin and cyromazine were sprayed alternately once every 2 wk throughout the growing season. Methornyl and rnetharnidophos, and methomyl and cypermethrin were similarly applied alternately. Yellow sticky traps were not a reliable method for determining the effects of these insecticides on L. huidobrensis population levels in small plots. Evaluations of population levels were based on emergence of insects from plants in the laboratory. There were no significant differences between leafminer or parasitoid populations from nontranslaminar insecticides versus the control. The translaminar insecticides significantly reduced leafminer and parasitoid populations. Parasitoids and leafminers were not evenly distributed in the plant; significantly more were found in the outer whorls of petioles than in the inner whorls. Yield was consistently and significantly higher in translaminar-insecticide-treated plots. Implications of these results on management practices are discussed.