Synergistic activity of combination of Metarhizium anisopliae and beta-cypermethrin on Locusta migratoria manilensis (Mey.).

In this paper,synergistic activity of combinations of Metarhizium anisopliae and beta-cypermethrin on Locusta migratoria manilensis(Mey.) was evaluated by calculating co-toxicity coefficient(CTC).The CTC indices were over 120 for the combinations containing 0.5%-1.5%(w/v) beta-cypermethrin.The CTC for the optimized formulation,i.e.1.0% beta-cypermethrin plus 1×1010 conidia/ml M.anisopliae,reached 268.92 and 375.93,respectively,after 4 and 5 days' treatment.When locusts were treated at room conditions with the optimized formulation diluted at the rate of 1∶2 and 1∶3,accumulative mortality after 5 days reached 97.8% and 97.3%,respectively,significantly higher than that treated with 1×1010 conidia/ml M.anisopliae.In the field,only 2.4% and 4.4% of locusts survived 6 days after spray with the optimized combination diluted at 1∶2 and 1∶3,respectively,which were significantly lower than that treated with M.anisopliae alone on the 9th d.The results show that combinations of M.anisopliae and beta-cypermethrin have an obviously synergistic effect on L.migratoria manilensis.