Toxicity Measure of Buprofezin, Nitenpyram and Their Mixtures to the Third Instar Nymphs of Brown Planthopper

Under the indoor temperature conditions, rice seedlings impregnation and rice stem impregnation methods were adopted to determine the toxicities of buprofezin, nitenpyram and their mixture to the third instar nymphs of brown planthoppers. The co-toxicity coefficient method introduced by Sun Yun-pei was adopted to evaluate the combined effects of the different mixtures of buprofezin and nitenpyram. The results of rice seedlings impregnation technique revealed an LC50 of 1.68 mg/L and CTC of 191.53 when buprofezin to nitenpyram mass ratio was kept at 4:1. On the other hand, with rice stem impregnation method, the corresponding values recorded for LC50 and CTC were 2.08 mg/L and 203.38 respectively. Furthermore, the LC50 and CTC were found to be 1.80 mg/L and 178.76 respectively with a mass ratio of 4:1 of xylene EC mixture of buprofezin and nitenpyrams by rice seedlings impregnation method. The LC50 and CTC values were however 2.17 mg/L and 194.94 respectively when measured with the help of rice stem impregnation technique. When Jatropha Bio-diesel was employed as an agent in the mixture of buprofezin and nitenpyram, the efficiency was enhanced significantly. This is evident from the figure that bio-diesel EC of buprofezin and nitenpyram with a mass ratio of 4:1 showed an LC50 of 1.39 mg/L and CTC of 231.49 when measured by rice seedlings impregnation method, whereas with rice stem impregnation method the corresponding value were 1.57 mg/L and 322.44 respectively.