INTEGRATED MANAGEMENT OF THE ONION MAGGOT (DIPTERA, ANTHOMYIIDAE)

In the absence of crop rotation, onion maggot, Delia antiqua (Meigen), control was inadequate (<10% plant loss) in field trials within a com mercial onion production area when susceptible and potentially resista nt onion genotypes were treated with chlorpyrifos at planting. However , when treatments were applied to the same entries in an area that had been rotated completely out of onion production the previous year, ex ceptional onion maggot damage reduction was noted (<2% plant losses). In the nonrotated area, one genotype (PI 432715) had reduced onion mag got damage compared with that of susceptible onion cultivars when trea ted with half rates of chlorpyrifos. Rotation of complete production a reas can provide effective onion maggot control. When rotation is not possible, integration of plant resistance and judicious application of insecticides may be appropriate.