Resistance to Imidacloprid and Effect of Three Synergists on the Resistance Level of Brown Planthopper

Imidacloprid is a neonicotinoid insecticide that is neurotoxic to the insect. This insecticide has been used to control Brown Planthopper (BPH), Nilavarpata lugens. This research aimed to study the effect of imidacloprid and the synergists effect on the resistance level of BPH. Laboratory selection on BPH population increased the resistance ratio to 50.64 times. Field population from Banyumas and Cilacap reared to the 5th-6th generations were also exhibited a high resistance of 18.57 and 19.68 times, respectively. The addition of synergists. PBO (Piperonyl butoxide), DEM (Diethyl maleate), and DEF (s,s,s-tributyl phosphorotrithioate) with 1: 4 ratio indicated synergists effects to the resistant population. Synergism ratio values were 8.61, 4.29, and 3.25 respectively of indicating that PBO was the stronger synergism to reduce LC50 of the resistant population to 3.94 ppm. These results may indicate the cytochrome P450 monooxygenases may involve in BPH-resistant mechanism to imidacloprid.