Toxicity and Field Efficiency of Certain Insecticides Against the Subterranean Termite, Psammotermes hypostoma Desneux (Isoptera: Rhinotermitidae)

The subterranean termite, Psammotermes hypostoma Desneux (Isoptera: Rhinotermitidae)is considered one of the most dangerous termites in urban, rural and agricultural areas in the desert belt of Assiut governorate, Egypt. Organophosphate insecticides such as chlorpyrifos have been recommended to control subterranean termites in Egypt. The present research was conducted to evaluate the toxicity, persistency and effectiveness of chlorpyrifos (chlorzan 48% EC), imidacloprid (imidammex 70% WG), chlorantraniliprole (coragen 20% SC), indoxacarb (avaunt 15% EC) and spinosad (tracer 24% SC) against subterranean termites. The toxicity of these insecticides was tested against field strain of the subterranean termites using the cardboard dip-bioassay technique under laboratory conditions. The toxicity index after 12 and 24 hr exposure showed that chlorpyrifos has the highest termiticidal activity, with LC_50s 1.19 and 0.13 ppm, followed by imidacloprid with LC_50s 3.24 and 0.61 ppm, while spinosad was the least toxic one with LC_50s.9.96 and 4.95 ppm. Furthermore, chlorpyrifos, imidacloprid and chlorantraniliprole registered significantly high percent reduction of the infested rural homes by subterranean termite, P. hypostoma, while indoxacarb and spinosad recorded the lowest reduction percentage after 30, 60, 90 and 120 days of treatment. In addition, the efficiency and residual effects of chlorpyrifos persisted up to 120 days followed by imidacloprid and chlorantraniliprole after treatment. Results of this study indicated that, chlorpyrifos exhibited the most powerful pesticide among all the insecticides tested, and imidacloprid and chlorantraniliprole were highly effective and it is given as unique and hopeful trends against subterranean termites under field conditions.