Mistura de deltametrina e clorpirifós no manejo da resistência de Blattella germanica   (Linnaeus, 1757) (Dictyoptera: Blattellidae) a deltametrina

Abstract

SALMERON E, OMOTO C. 2004. Mixture of deltamethrin and chlorpyrifos for managing Blattella germanica   (Linnaeus, 1757) (Dictyoptera: Blattellidae) resistance to deltamethrin. Entomotropica 19(2):85-89. The viabilility of the use of deltamethrin and chlorpyrifos mixture for managing B. germanica resistance to deltamethrin was evaluated on susceptible and resistant strains of B. germanica by residual tarsal-contact bioassay. The following treatments were evaluated: (a) 12.5 mg deltamethrin/m2; (b) 240 mg chlorpyrifos/m2; (c) mixture of 12.5 mg deltamethrin + 120 mg chlorpyrifos/m2; (d) mixture of 12.5 mg deltamethrin + 240 mg chlorpyrifos/m2 and (e) control. The application of the treatments was done on tiles. The infestations of German cockroaches on treated-tiles were done on 0, 7, 14, 28, 35 and 42-day old residues. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. In the mixture of 120 mg of chlorpyrifos (half of the recommended rate) in 12.5 mg of deltamethrin/ m2, the discrimination of the strains was detected from 14-day old residues and with 240 mg of chlorpyrifos in the mixture, the discrimination was possible only with 42-day old residues. Thus, the commercial recommended rates of deltamethrin and chlorpyrifos in the mixture (12.5 mg deltamethrin + 120 mg chlorpyrifos/m2) should be revaluated for managing B. germanica resistance to deltamethrin