Residual contact toxicity of spinetoram against granary weevil (Sitophilus granarius L.) and confused flour beetle (Tribolium confusum Du Val.)

Abstract: In present study, residual contact toxicity of Spinetoram suspension applied to wheat grains against Sitophilus granarius L. and Tribolium confusum du Val. adults were investigated under laboratory conditions. In laboratory bioassays, S. granarius and T. confusum adults were exposed to wheat grains sprayed with Spinetoram suspension at 0.5, 1, 2.5, 5 and 10 ppm (mg active ingredient/kg wheat) at 26 ± 1 °C temperature, 65 ± 5 % r.h. and completely dark condition. Knockdown and mortality of the adults were recorded after 1, 3, 5 and 7 days of exposure and 35-40 days later the wheat was examined for progeny production. The suspension treatments at all concentrations after 1 day of exposure resulted in low mortality of S. granarius and T. confusum adults. Mortality of S. granarius and T. confusum adults increased after 1 day of exposure period. Spinetoram treatment at 1 ppm and above concentrations after 3 days of exposure resulted in almost 100% knockdown or mortality of S. granarius and T. confusum adults and completely hindered their progeny production. On the other hand, 100% knockdown or mortality of T. confusum adults were obtained at 10 ppm concentration of Spinetoram treatment after 3 days of exposure.The results obtained from biological tests indicated that T. confusum adults generally were more tolerant to Spinetoram treatments particularly at low concentrations and short exposure times than S. granarius adults. In conclusion, this study indicated that Spinetoram suspension treatment on wheat would be potential to be used for control of S. granarius and T. confusum.