Synergistic Effect of Bacillus thuringiensis and Azadirachtin against Chilo suppressalis

PurposeThe synergetic effect of Bacillus thuringiensis (Bt) and azadirachtin was studied by using rice stem borer as the test insect.

MethodTwo kinds of treatments, Bt pretreatment and direct mixture, were used to measure the synergistic effect against Chilo suppressalis, and the field control experiment was carried out.

ResultAfter Bt pretreatment, the LC₅₀ values of C. suppressalis were 1.15 mg/L and 0.42 mg/L after 24 h and 48 h, respectively, and the synergistic effect was obvious and better than the direct mixture. After Bt pretreatment, the effect of azadirachtin on the field control of C. suppressalis was significant. The insecticidal effect was 91.20%, the seedling-preserving effect was 94.64%, and the heart-burning rate was 0.23% after 14 days of application.

ConclusionAfter Bt pretreatment, the synergistic effect on azadirachtin is obvious, which is better than the two alone or direct mixture, which provides a basis for the development of new biological pesticides for the control of C. suppressalis.