Susceptibility of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) and Sitophilus oryzae (L.) (Coleoptera: Curculionidae) to Spinosad (Tracer®) as a Eco-friendly Biopesticide
Abstract. Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) are internal feeder of various stored grains and introducted as major stored product insect pests. Due to the resistance by insect pests and negative effects of synthetic pesticides to the environment, it is necessary to use novel and suitable compounds in insect pest's management. Spinosad is a bio-insecticide that is derived from fermentation of a bacterium Saccharopolyspora spinosa Mertz and Yao. In the present study, the toxicity of Tracer® as a spinosad based insecticidise was evaluated against R. dominica and S. oryzae. Insect species were kept in stored-products insects rearing room in Agriculture Faculty of Tehran University at 27 ± 2ºC, 65 ± 5% relative humidity. Adult insects were exposed to different concentrations of Tracer® by oral trials for 10 and 20 days exposure periods. The mortality data were subjected to probit analysis using SPSS software to estimate LC (lethal concentration) values and their related information. Tracer® showed strong toxicity against the adults of R. dominica and S. oryzae. Maximum mortality was occurred in the concentration of 250 and 80 ppm after 20 days exposure for R. dominica and S. oryzae, respectively. Direct relationship between mortality of insects with concentration and exposure period was found. Probit analysis displayed R. dominica (10-days LC50 = 49.89 ppm) was more susceptible than S. oryzae (10-days LC50 = 50.75 ppm) to Tracer®. Results of present study stimulated the utilization of Tracer® as an eco-friendly and safe agent for insect pests' management.
Article № eb.15107, ICID: 116555 [Full text - PDF]