Synergic effect between Bacillus thuringiensis Kurstaki HD1 5-endotoxins and Melia azedarach (Meliacea) methanolic extract against the larvae of Thaumetopoea pityocampa Den. & Schiff. (Lepidoptera, Notodontidae)

摘要

Bioassays with Melia azedarach against Thaumetopoea pityocampa larvae showed positive correlation between mortality (between 50 and 100%) and the used doses (5, 10 and 15 mg/cm2) after 24 h of application. This efficacy was similar to that of the Bacillus thuringiensis Kurstaki HD1 5-endotoxins (20 ug/ml, 40 ugl ml, 80 ug/ml, 150 ug/ml and 300 |jg/ml) which resulted in a caterpillars's mortality rate of 100% but three days after application, at the dose of 300 ug/ml. The use of the mixture M. azedarach and the 5-endotoxins of Bacillus thuringiensis Kurstaki HD1 gave 100% mortality, 24 hours after treatment only. Histologically, this effect resulted in vacuolation of the intestinal cells of the treated larvae with a significant reduction of pine needle consumption compared to untreated caterpillars.