| dc.description.abstract | The present study was carried out to determine the direct and residual effects of eight
pesticides namely abamectin, abamectin+bifenthrin, spinosad, chlorfenapyr,
deltamethrin, lambda-cyhalothrin, imidacloprid and thiamethoxam against Tetranychus
urticae Koch (Acari: Tetranychidae) and residual toxicity of these pesticides against the
pest and its predator Coccinella septempunctata L. (Coleoptera: Coccinellidae) adults.
The laboratory trials, abamectin caused 100% mortality of T. urticae within 3 hours,
abamectin+bifenthrin within 6 hours and other pesticides within 48 hours except
imidacloprid and thiamethoxam. The egg mortality for all pesticide treatments was
significantly higher than the control. Abamectin+bifenthrin and chlorfenapyr caused
100% egg mortality followed by abamectin (95%), deltamethrin (82%), lambdacyhalothrin (79%). On the other hand, thiamethoxam, imidacloprid and spinosad
showed 63, 65 and 71% egg mortality, respectively. In potted bean plants, abamectin,
abamectin+bifenthrin and chlorfenapyr showed significant mortality over control up to
21 days and the rest of pesticides showed up to 14 days. Abamectin and chlorfenapyr
showed higher residual efficacy against T. urticae but low efficacy against C.
septempunctata. Neonicotinoid, imidacloprid had the longest residual effect on adults
of C. septempunctata causing 20% mortality after 21 days; but lower toxicity against T.
urticae. Abamectin+bifenthrin residues caused >20% mortality of C. septempunctata
after 14 days of exposure. Therefore, abamectin and chlorfenapyr can be used for the
management of T. urticae because of their higher toxicity against T. urticae and less
residual activity to C. septempunctata. | en_US |
