Effects of fenvalerate on detoxifying enzyme activities of Oedaleus infernalis

In order to determine the effects of fenvalerate on detoxification enzymes activities of Oedaleus infernalis, the enzyme inhibitors (piperonyl butoxide, PBO; three phosphoric acid phenyl esterm, TPP; diethylmeteate, DEM) effects synergy with in vivo enzyme activities in insects from different source were measured. The results showed that the LD50 of fenvalerate to in door population source O. infernalis was 4.38×10-3 μg·locust-1, to the field population source HG, LD and ZY in the Heilongjiang were 7.30×10-3 μg·locust-1, 7.21×10-3 μg·locust-1 and 22.98×10-3 μg·locust-1, respectively, which had the resistance ratio of 1.67, 1.65 and 5.25. Both PBO and TPP on indoor and field population source ZY to fenvalerate had synergistic effects, which had the synergistic ratio 2.16 and 3.91, 2.00 and 2.15, respectively. Comparing with field population source ZY, the activities of esterase and multiple function oxidase in the indoor population source significantly increased (P<0.05). After the induction of fenvalerate, the esterase activities rising ratios of field population source ZY and indoor population source were 2.25 and 1.59; and the multiple function oxidase activities rising ratio were 1.21 and 1.45, respectively. These above results showed that the activities of esterase and multiple function oxidase increased with the decreasing of sensitivity of O. infernalis to fenvalerate which suggested that esterase and multiple function oxidase were involved in the metabolism of fenvalerate in oedaleus infernalis, and the two enzymes wereone of the reasons for fenvalerate resistance.