Effects of a food source on red flour beetle (Coleoptera: Tenebrionidae) survival after exposure on concrete treated with cyfluthrin

The effects of a flour food source on survivorship of red flour beetles, Tribolium castaneum (Herbst),were determined after beetles were exposed every 2 wk for 16 wk for intervals of 15-120 min on concrete treated with cyfluthrin wettable powder. Knockdown generally increased as exposure interval increased but declined as residues aged. After week 4, survival was usually >60% at all exposure intervals for beetles placed on flour after they were exposed to the insecticide. Survival decreased as exposure interval increased for beetles not provided with flour, but longer exposure intervals were required to kill 90% of the population as the cyfluthrin residues aged. The flour may have enhanced survival by physically removing the insecticide from the insect cuticle and by providing the beetles with nutritional resources. Results demonstrate the importance of sanitation in mills and food warehouses. Insecticide treatments may be less effective unless good sanitation is practiced.