Impact of accumulated food on survival of Tribolium castaneum on concrete treated with cyfluthrin wettable powder

Experiments were conducted to determine if the presence of wheat flour and other substrates would affect the residual efficacy of 20% cyfluthrin wettable powder applied to concrete at the low label rate of 100 mg (20 mg [AI])/m(2). Adults of Tribolium castaneum (Herbst), the red flour beetle, were exposed for 2 h on treated concrete covered with wheat flour, then removed and held for 1 week without food. Knockdown decreased and survival increased as the percentage of area covered by flour increased. Covering the concrete with flour for 2 weeks and removing it before T. castaneum were exposed for 2 h did not affect knockdown, but subsequent recovery and survival increased in proportion to the area of the concrete that had been covered. Tribolium castaneum were also exposed for 2 h on treated concrete, then held in Petri dishes that contained either no food material or 1 g of flour, pine sawdust, or wheat kernels. More beetles survived in Petri dishes containing flour or sawdust than in dishes with wheat kernels. The presence of flour or other food substrates may affect the residual efficacy of cyfluthrin by forming a barrier so that insects do not come in contact with the residues, providing exposed insects with nutrition, or enabling the insects to physically remove insecticide particles after they are exposed on a treated surface. Published by Elsevier Science Ltd.