Responses of the Four Larval Stages (L1 To L4) of the Avian Malaria Vector Culiseta longiareolata Exposed to Spinosad (Naturally Derived Insecticide)

The sensitivity of the first to fourth-stage larvae of Culiseta longiareolata (Diptera: Culicidae) treated with Spinosad was the first aim of this work. Five concentrations were administered for the toxicological tests (0.05, 0.1, 0.5, 1 and 5 μg/l). The results gained showed us an insecticidal effect which increases, according to the concentration and the time of exposure. The average lethal concentration LC50 of the L1 stage was in the order of 2.46 μg/l and the LC90 was 3.28 μg/l. For the L2 stage, the LC50 calculated was a 2.88 μg/l and LC90 with a 3.63 μg/l. For the L3 stage, the LC50 obtained was a 3.06 μg/l and the LC90 with a value of 3.88 μg/l. The LC50 of L4 stage calculated was a 3.16 μg/l, and the LC90 was a 3.93 μg/l. Based on the results of thisstudy, it was noted that the premature stages (L1 and L2) were sensitive to the product used as compared withthe tardy stages (L3 and L4) on all which was resistant according to the calculated toxicological parameters.