The responses of the blueberry maggot fly, Rhagoletis mendax Curran, and the apple maggot fly, Rhagoletis pomonella (Walsh), to GF120, a baited formulation of the insecticide spinosad, were tested in field experiments during the summer of 2002. Laboratory observation studies were also conducted during 2003 with R. pomonella. Captures of adult R. mendax and R. pomonella on baited spheres in untreated plots were significantly higher than on spheres hung in GF120 treated plots. However, captures of flies in plots treated with SpinTor or GF120 blank (no active ingredient) were not significantly different from either untreated or GF120 treated plots. Larval infestation of fruit in both SpinTor and GF120 treated blueberry plots was significantly lower than in untreated or GF120 blank treated plots. Laboratory observations with R. pomonella suggest that while ingestion of GF120 results in fly knockdown, it is not necessarily attractive to the fly. It is possible that foraging flies happen upon protein-rich droplets of GF120 and become arrested, whereby phagostimulation commences resulting in ingestion of toxicant. Arrestment at GF120 droplets may decrease the likelihood that flies will move to sphere traps. This mechanism may explain the lower trap catches observed in the bait treatment field plots for both species. In addition, reduced adult capture and larval infestation in GF120 treated fruit plots is likely due to the increased opportunity for ingestion of the active ingredient resulting in lethal or sublethal effects. Results from field trials with GF120 during the summer of 2003 corroborate 2002 results.
Species 1: Diptera Tephritidae Rhagoletis pomonella (apple maggot)
Species 2: Diptera Tephritidae Rhagoletis mendax (blueberry maggot)
Keywords: bait spray, spinosad
Back to Student Competition Ten-Minute Papers, Cd3, Behavior and Ecology
Back to Student Competition TMP Orals
Back to The 2003 ESA Annual Meeting and Exhibition