Caffeic Acid and Biopesticides Interactions for the Control of Storage Beetles

Infestations of stored-product pests cause significant losses of agricultural produce every year. Despite various environmental and health risks, chemical insecticides are now a ready-to-use solution for pest control. Against this background and in the context of Integrated Pest Management research, the present study focuses on the potential insecticidal effect of caffeic acid at five different concentrations (250, 500, 750, 1500 and 3000 ppm), and their combination with Cydia pomonella Granulovirus (CpGV), Bacillus thuringiensis subsp. tenebrionis and Beauveria bassiana strain GHA on three major insect stored-product beetle species, Tribolium confusum (Coleoptera: Tenebrionidae), Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) and Trogoderma granarium Everts (Coleoptera: Dermestidae). Treatment efficacy was expressed as mortality in relation to exposure time and adult species number. Compared to the control, the results showed a clear dose-dependent pesticidal activity, expressed as significant adult mortality at a high-dose application, although some of the combinations of caffeic acid concentrations with the other substances acted positively (synergistically and additively) and some negatively. Based on our results, bioinsecticides can be combined with plant compounds such as caffeic acid and be integrated with other modern IPM tools in storage facilities.