Rearing, biology and control of cabbage maggots, Delia sp. (Diptera: Anthomyiidae) using Metarhizium anisopliae soil treatments under laboratory conditions

Cabbage maggots, Delia sp. are a key pest of Cole crops worldwide. Although insecticides are the mainstay in conventional fields, management of cabbage maggot in organically grown fields can have stand losses of greater than 50%. Cabbage maggots were collected from fields in Guadalupe California and reared on slices of rutabaga until pupation. Flies were released into cage and fed special diet. Potted rutabaga was provided to ovipositing adult files and food for maggots. Maggots required 18 to 26 days to pupate, and emerge as adults after 11 to 19 days. These flies lived for 24 to 38 days. Mean fecundity per females was 78.3, with egg hatch ranging from 3 to 6 days. Metarhizium anisopliae formulations, granular NZBPC2101 and EC NZBPC2102 were evaluated against maggots and compared with Seduce (44 lb/ac) and untreated. Ten maggots were released into glass jars containing 100 gm of treated moist soil and a slice of rutabaga as a food. Test insects were taken out at 14 DAT for evaluation. Larval mortality recorded while pupae kept for 21 days for observations on emergence. Maximum larval mortality reached 23.33% in Seduce, however, treatments of NZBPC2101 @ 0.5 gm/100 gm and NZBPC2102 @ 1 ml/100 gm of soil demonstrated 16.67% compared to untreated (6.67%). Data indicate that minimum of 26.67% emergence of healthy adult in NZBPC2102 @ 1 ml/100 gm and 0.1 ml/100 gm however, it was 73.33% in untreated. In conclusion, NZBPC2101 and NZBPC2102 forced early pupation of cabbage maggots. This resulted in pupal mortality to the extent that emergence of healthy cabbage maggots flies was affected.