Comparative effectiveness of different insecticides for organic management of blueberry maggot (Diptera: Tephritidae)

Laboratory and field assays using insecticides for organic pest management were conducted on the blueberry maggot, Rhagoletis mendax Curran. Topical exposure of flies to spinosad (Entrust), pyrethrum (PyGanic 1.4 EC), azadirachtin (Aza-Direct), and phosmet (Imidan 70-W) resulted in significantly higher mortality compared with the water control after 2 and 24 h. After 24 h, there were no significant differences in fly mortality among treatments of Entrust, PyGanic, or Imidan, whereas fly mortality to Aza-Direct was significantly lower. Another laboratory assay evaluated mortality of flies after residual exposure to these insecticides on leaves, after 24 and 48 h. In this assay, there were no significant differences in fly mortality after 48 h among treatments of PyGanic, Aza-Direct, and the water control, whereas significantly higher fly mortality resulted from exposure to Entrust and Imidan. A repellency assay found no measurable effects of Aza-Direct. Large-scale field trials found no treatment effect for number of adults of the blueberry maggot captured in sticky traps; however, there were significantly lower levels of fruit-infesting larvae in treated plots compared with the untreated control. Spinosad bait (GF-120 NF Naturalyte Fruit Fly Bait), Entrust, and PyGanic were not different from imidacloprid (Provado 1.6 F). However, there was a significantly higher infestation in the plot treated with azadirachtin (Agroneem) compared with Provado. Overall, the insecticides evaluated in these trials showed good ability to control blueberry maggot, suggesting that they can be incorporated in a blueberry maggot management program under organic standards.