Laboratory evaluation of Imidacloprid against Microtermes obesi (Holmgren) (Isoptera: Macrotermitinae)

A laboratory bioassay was developed to test the toxicity,repellency and tunneling behavior of imidacloprid against microtermes obesi (holmgren). in this study >90% of termites died after 96 h exposure to 100 μg ml-1 of imidacloprid and after 168 h all the termites died at all the tested concentrations. when tested for persistence (exposure to soil aged one month after treatment),>90% mortality was observed in soil treated with 100 μg ml-1,50 μg ml-1 and 25 μg ml-1 after 120 h exposure. repellency test results proved imidacloprid to be a non-repellent insecticide at all tested concentrations (i.e.,100 μg ml-1,50 μg ml-1,25 μg ml-1,12.5 μg ml-1,6.25 μg ml-1,3.125 μg ml-1 and 1.562 μg ml-1). when tested for f-1 (0.97) toxicity,it was also evident that it took more than 8 h to give 97% mortality. tunneling behavior was also studied for cumulative tunnel distance,maximum tunnel height and number of tunnels. at higher concentrations,not only was there more mortality,but also less cumulative tunnel distance and a reduced number of tunnels. © pakistan academy of sciences.