Combination of protein-rich pea flour and pea extract with insecticides and enzyme inhibitors for control of stored-product beetles

Protein-rich pea flour and its extract are toxic to stored-product beetles and, at a concentration of 0.1%, can control these insects in a granary. To reduce the concentration of protein-rich pea flour needed to control stored-product beetles, natural products or currently used grain protectants (diatomaceous earth, neem, Bacillus thuringiensis (Berliner), malathion, and pyrethrum) were mixed with protein-rich pea flour in wheat. Mixtures were tested against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), and the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujidae). Neem and protein-rich pea flour acted synergistically against T. castaneum. Malathion and protein-rich pea flour acted synergistically against S. oryzae. Protein-rich pea flour combined with diatomaceous earth or pyrethrum acted additively against S. oryzae. All other combinations acted antagonistically. An extract from protein-rich pea flour reduced feeding of S. oryzae, and three enzyme inhibitors, piperonyl butoxide, profenofos, and diethyl maleate, were tested for their possible synergistic effects on feeding deterrence and mortality. Piperonyl butoxide and pea extract had additive effects, and diethyl maleate had no effect on the feeding and mortality of insects. Profenofos alone killed all insects in 3 days. The flour consumption of S. oryzae was positively correlated with LT50 (time to 50% mortality) in flour disks treated with pea extract.