Abstract

Pretransplant applications of imidacloprid, acetamiprid and thiamethoxam, and a mixture of imidacloprid and cyfluthrin were evaluated on tobacco (Nicotiana tabacum L.) seedbeds for the control of the aphid Myzus persicae nicotianae Blackman. Corrected mortality at 48 h after aphid release on plants in a seedbed was over 80% almost permanently up to 75 days after application (DAA) with a dose of 14 g a.i. m-2 seedbed of imidacloprid. In another experiment, the same level of corrected mortality was maintained by doses of 5.6 g a.i. m-2 seedbed of acetamiprid and 7 g a.i. m-2 seedbed of thiamethoxam up to 50 and 30 DAA, respectively. After 30 DAA for all the insecticides evaluated in both experiments, corrected mortality at 24 h was lower than at 48 h after aphid release on treated plants, which shows a limited knock down effect of these treatments. Finally, in another experiment a mixture of 10.5 and 0.21 g a.i. m-2 seedbed of imidacloprid and cyfluthrin, respectively, showed a good knock down effect, with corrected mortality higher than 80% up to 70 DAA at 48 h and without significant differences with corrected mortality at 24 h after aphid release on plants.