Synergistic effects of chlorpyrifos with piperonyl butoxide (pbo) against the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

To investigate the co-toxicity and co-efficient activity of Chlorpyrifos (Dursban 20EC), an organophosphate and Piperonyl butoxide (PBO) against the lesser meal worm Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) (A. diaperinus). The repellent activity was carried out by the residual film assay technique. Statistically the dose mortality relationship was expressed as a median lethal dose (LD50) by the probit analysis. The regression lines and isoboles were drawn using the Fig-P (Biosoft) package. The Co-efficient values showed that all ratios of chlorpyrifos and piperonyl butoxide offered synergistic action to both larvae and adult. We observed that the toxicity of the chlorpyrifos was decreased as the ratio (amount) of PBO was increased. The individual LD50 value of chlorpyrifos for adult is 0.1241 µg/cm2. But…