Cyfluthrin WP and EC Formulations to Control Malathion-Resistant Red Flour Beetles and Confused Flour Beetles (Coleoptera: Tenebrionidae): Effects of Paint on Residual Efficacy²

Malathion-resistant red flour beetle and confused flour beetle field strains and a pesticide-susceptible laboratory strain of each species were exposed on unpainted and painted galvanized steel panels treated with cyfluthrin EC and WP formulations at label rates. Residues from both formulations applied to unpainted steel killed 99.8% of the insects after 1 h exposure for up to 235 d after treatment. Equivalent control on painted panels lasted approximately 3 wks and required 24 h exposure. Residual mortality on painted panels treated with cyfluthrin WP and EC quickly declined; tests with red flour beetles and confused flour beetles were discontinued after 116 and 123 d, respectively. All of the malathion-resistant strains were as susceptible as the laboratory strain to cyfluthrin, and there was no difference between the EC and WP formulations.