Effects of cyromazine and abamectin on the leafminer, Liriomyza huidobrensis and its parasitoid, Diglyphus isaea in celery

Field trials were conducted for 2 yr on celery (Apium graveolens L.) to determine the effects of two translaminar insecticides (abamectin and cyromazine) on the agromyzid leafminer, Liriomyza huidobrensis (Blanchard), and the eulophid parasitoid, Diglyphus isaea Walker. Abamectin and cyromazine were applied once early in the growing season by spray or drip application. Yellow sticky traps and leaf samples were used to monitor population levels; a gas chromatograph-mass spectrometer was used to monitor cyromazine residues within the celery plants during 1 yr. Spray applications of abamectin and cyromazine significantly reduced larval leafminers and D. isaea. Contrary to grower practices, application of cyromazine by drip irrigation systems had minor effects on larval leafminer and D. isaea as compared to spray application. Cyromazine residues in the plants treated by spray application declined sharply after 1 wk, and no residues were detected 2 wk after application; less than 0.05 ppm cyromazine residues were detected in plants treated by drip application. Implications of these results on management practices are discussed.