Wirksamkeit von Extrakten des Neembaums (Azadirachta indica) gegenüber Trogoderma granarium an gelagerten Erdnüssen

Abstract

Petroleum ether extracts of leaves and kernels of the neem plant, Azadirachta indica A. Juss, mixed at varied dosages of 0, 50, 150, 250, 350 and 500 mg/ml with decorticated groundnut seeds (50 g), were tested for their potential to control the Khapra beetle, Trogoderma granarium Everts. The kernel extract was more potent than the leaf extract. The number of emerged adults decreased with increasing extract concentrations for both leaves and kernels. The number of emerged adults in the control (72.2 ± 4.83) was significantly higher (P < 0.05) than all neem extract variants. The mortality of adults and larvae increased with increasing extract concentrations from 36.42 ± 4.62 % in the control to 60 ± 2.24 % at 500 mg/ml for leaf extract and to 55.08 ± 3.62 % at 500 mg/ml for kernel extract. Seed damage expressed as the number of holed seeds and weight loss of infested groundnut was significantly reduced (P < 0.05) in each treatment as dosages increased. There was no significant reduction in the viability of groundnut seeds treated with neem extracts when compared with the control. Regression analysis showed positive correlations between dosages, adult and larval mortality and seed germination in each treatment. A negative relationship was observed between the dosages and emergence of offspring, seed damage and weight loss for each treatment.