Combined effects of the assassin bug alloeocranum biannulipes mont. And sign. (hemiptera: reduviidae) and botanical powders in the control of the stored yam chips beetle, dinoderus porcellus lesne (coleoptera : bostrichidae)

Abstract

Background Dinoderus porcellus Lesne (Coleoptera: Bostrichidae) is the main pest of stored dried yam chips that causes significant losses in a few months. The assassin bug, Alloeocranum biannulipes (Montrouzier & Signoret) (Hemiptera: Reduviidae) and the Khaya senegalensis (Desv.) A. Juss. (Meliaceae), Blighia sapida K. Koenig (Sapindaceae) and Bridelia ferruginea 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 A. biannulipes in the integrated management of D. porcellus under laboratory and farm conditions. Various leaf powders were tested at a concentration of 6% (w/w) with or without the predator. Yam chips mixed with leaf powder from each species served as negative and those mixed with a synthetic insecticide as positive controls. Results The results revealed that no combination of leaf powders and predators could induce complete mortality of D. porcellus like the synthetic insecticide. No significant difference in terms of the survival of A. biannulipes exposed to botanical powders was observed compared to the positive control. Under farm conditions, B. ferruginea leaf powder showed a sub-lethal effect on the predator A. biannulipes and no impact on the abundance of D. porcellus. However, the survival of D. porcellus was significantly reduced by the combination of K. senegalensis leaf powder and A. biannulipes, which did not allow the reproduction of the predator. Conclusions We recommend the combination of K. senegalensis leaf powder and A. biannulipes for the short-term conservation of yam chips as part of an augmentative biological control program. For long-term conservation, we suggest the use of a combination of B. sapida leaf powder with the predator A. biannulipes because it presented a reduced population of D. porcellus after 8 weeks of storage and offspring of A. biannulipes.