Characterization of pyrethroid and carbamate resistance in a Malaysian field collected strain of the German

A field strain of the German cockroach (Melia), collected from the kitchen of a hotel in Kuala Lumpur, Malaysia demonstrated moderate resistance to bendiocarb and low resistance to propoxur and deltamethrin when tested with modified W.H.O. glass jar method. Low resistance was also detected when the strain was tested with DDT. Resistance level to bendiocarb and deltamethrin was partially suppressed with piperonyl butoxide (PBO) and S,S,S-triphosphorotrithioate (DEF), suggesting the possible involvement of monooxygenase and elevated esterase in the resistance. There is also an indication of the involvement of kd~-type resistance in this strain due to inability of PBO and DEF to suppress pyrethroid resistance. Biochemical assays using model substrate aand b-naphthyl acetate with modified microplate technique demonstrated elevated esterase activity in the ML strain. A high elevated esterase gene frequency was estimated in this strain using Hardy-Weinberg equilibrium equation.