Insecticidal Activity of Natural Capsaicinoids Against Several Agricultural Insects

In this paper, the insecticidal activity of natural capsaicinoids (NC) and reference ingredients (imidacloprid, abamectin, and pyridaben, which are active ingredients of commercial pesticides) against 14 agricultural insects was studied in both the laboratory and field. The results of insecticidal activity in the laboratory showed that the median lethal concentration (LC50) and 90% lethal concentration values of the NC against 14 agricultural insects were greater than those of reference ingredients and the NC had a weaker relative toxicity than the corresponding reference ingredients. The NC showed impressive insecticidal activity when it was used to control Aphis gossypii from Cucumis sativus (LC50 152.82 mg L？1) but unimpressive insecticidal activity when used against Ectropis obliqua hypulina and Pieris rapae (LC50 1557.47 and 1502.48 mg L？1, respectively), which revealed that the insecticidal spectrum of NC was confined. Field experiments showed that the control effect of successively spraying the NC 2 times against insects was significantly higher than the effect of spraying 1 time