MALATHION RESISTANCE IN TRIBOLIUM-CONFUSUM DUV (COLEOPTERA, TENEBRIONIDAE) - CORRELATING RESULTS FROM TOPICAL APPLICATIONS WITH RESIDUAL MORTALITY ON TREATED SURFACES

Nine Tribolium confusum Duv. field strains were exposed on galvanized steel and plywood panels treated with malathion at 1.63 g a.i. per 0.28 m2. Resistance frequencies for these strains were measured by topical application of a discriminating dose of 300 ppm per 0.5-mu-l per insect. Residues on galvanized steel controlled a susceptible laboratory strain for 5 weeks and three susceptible field strains for 3 weeks. Six resistant field strains were controlled for approx. 1 week. Known resistance frequencies were correlated to residual mortality on galvanized steel for 1-6 weeks. Residues on plywood were nearly 100% effective against all field strains and the susceptible laboratory strain for 12 weeks.