Insecticidal activity of camptothecin against Nilaparvata lugens, Brevicoryne brassicae, and Chilo suppressalis.

Greenhouse tests showed that 0.2% camptothecin emulsifiable concentrate (EC) has strong contact toxicity to three agricultural pests, with LC50 and LC90 values of 0.1-0.6 and 0.4-5.0 mg liter(-1), respectively. The descending order of susceptibility was Nilaparvata lugens (Ståhl) > Brevicoryne brassicae (L.) > Chilo suppressalis (Walker). Field tests showed that the corrected mortality of B. brassicae and N. lugens was 94.6 and 69.1%, respectively, which was not significantly different from that with 10% imidacloprid WP at 98.4 and 63.4%, respectively. The corrected mortality of C. suppressalis was 85.8%, which was not significantly different from that with 5% Regent SC at 93.0%. Camptothecin EC showed no acute oral toxicity to the mouse (LD50 > 5000 mg/kg) nor acute dermal toxicity (LD50 > 2000 mg/kg).