Insecticidal activities of propiconazole against Spodoptera litura (Lepidoptera: Noctuidae)

On the ground of studying the cytotoxicity of 11 kinds of pesticides, propiconazole, which had the highest toxicity against Spodoptera litura (SL) cells, was chosen to further investigate its toxicology. The results showed that the mortality of SL cells treatment by propiconazole at concentration of 100 μg/mL was 98.08%. The LC_ 50 value of propiconazole against SL cells was 20.31 μg/mL 36 h after treatment. Propiconazole reduced the protein content of SL cells obviously. When injected with propiconazole at concentration of 0.5 μg/larva for 72 h, the blood content and the number of corpuscles of the 4th-instar larvae decreased by 26.80% and 25.26% respectively; while at concentration of 1.0 μg/larva, they decreased by 37.67% and 36.32% respectively. Under the both concentrations, the weight of larvae decreased notably. In addition, propiconazole reduced the total sugar and protein content in hemolymph of S. litura larvae. After treatment for 96 h and 120 h, the LD_ 50 values of propiconazole against 4th-instar larvae of S. litura were 0.59 μg/larva and 0.45 μg/larva respectively. The high toxicity of propiconazole against cells and larvae of S. litura implied the possibility for propiconazole analog in controlling insect pests.