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 wetta ble 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 e xposed for 2 h on treated concrete covered with wheat flour, then removed a nd held for 1 week without food. Knockdown decreased and survival increased as the percentage of area covered by flour increased. Covering the concret e with flour for 2 weeks and removing it before T. castaneum were exposed f or 2 h did not affect knockdown, but subsequent recovery and survival incre ased in proportion to the area of the concrete that had been covered. Tribo lium 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 s awdust, or wheat kernels. More beetles survived in Petri dishes containing flour or sawdust than in dishes with wheat kernels. The presence of flour o r other food substrates may affect the residual efficacy of cyfluthrin by f orming a barrier so that insects do not come in contact with the residues, providing exposed insects with nutrition, or enabling the insects to physic ally remove insecticide particles after they are exposed on a treated surfa ce. Published by Elsevier Science Ltd.