Effect of botanical powders and the assassin bug, Mont. and Sign. (Hemiptera: Reduviidae) against Lesne (Coleoptera: Bostrichidae) infesting yam chips.

BACKGROUND

Lesne (Coleoptera: Bostrichidae) is the main pest of stored dried yam chips that causes significant losses in less than 3 months. The assassin bug, (Montrouzier & Signoret) (Hemiptera: Reduviidae) and the African mahogany ( (Desv.) A. Juss. (Meliaceae)), the ackee ( K. Koenig (Sapindaceae)), and bridelia ( Benth. (Euphorbiaceae)) leaf powders have proven to be efficient in the control of this pest.

METHODS

This study aims to evaluate the compatibility of the leaf powders of these medicinal plants and the predator in the integrated management of under laboratory and farm conditions. Various leaf powders were tested at a concentration of 6% (w/w) with or without the predator. Infested yam chips without any treatment served as negative control and those mixed with a synthetic insecticide as positive control. The mortality rate of was recorded under laboratory conditions. While, the dynamic population of , their damage, and weight loss of yam chips were recorded 8 weeks after treatment under farm conditions.

RESULTS

The results revealed that no combination of leaf powders and predators could induce complete mortality of like the synthetic insecticide. No significant difference in terms of the survival of exposed to botanical powders was observed compared to the positive control. Under farm conditions, leaf powder showed a sub-lethal effect on the predator and no impact on the abundance of . However, the survival of was significantly reduced by the combination of leaf powder and which did not allow the reproduction of the predator.

CONCLUSIONS

Our results suggest that an augmentative biological control program with the release of after the introduction of leaf powder is practicable for the management of in yam chips.