Appraisal of Current Strategies for Controlling Onion Maggot (Diptera: Anthomyiidae) in New York State

Abstract

Chlorpyrifos applied in the furrow at planting in mid-May to control onion maggot, Delia antiqua (Meigen), infestations gave adequate control for 8 weeks (mid-July). In laboratory and field tests, undamaged onion plants grown with or without insecticide treatment became resistant to maggot invasion after 12 weeks of plant growth (about mid-August in all but one field). Maggots died primarily through failing to establish on the bulbs rather than through desiccation. Late-season (third generation) damage was most prevalent in rows where plants had been damaged during weekly applications of parathion sprays. Improvements to the current strategy of onion maggot control may be effected by development of a more persistent soil treatment, selection of onion cultivars with midseason resistance to invasion, and effective adulticide treatments for midseason application.