Ovipositional Preference and Larval Survival of the Onion Maggot (Diptera: Anthomyiidae) as Influenced by Previous Maggot Feeding

Onion maggot, Delia antique (Meigen), ovipositional preference and subsequentv larval survival on maturing onion bulbs with different levels of larval feeding and microbial damage were determined. Females preferentially oviposited on onion plants with low to moderate damage compared with healthy or severely damaged plants. Newly hatched onion maggots successfully colonized 90-100% of slightly to moderately damaged bulbs, which were preferred for oviposition, but colonized only 15-20% of the severely damaged and healthy plants. Weight gains for larvae reared on healthy or slightly damaged bulbs did not differ; both gains were greater than for larvae reared on more severely damaged bulbs. Overall larval survival was highest on slightly damaged bulbs. High densities of onion maggots are found on recently damaged fall onions, because they are preferred by D. antique for oviposition and are highly suitable larval food.