Insecticide Resistance Mechanisms in the German Cockroach, Blattella germanica (L.)

Insecticide resistance in the German cockroach has been identified for all major classes of insecticides currently in use. Resistance mechanisms that have been identified include increased metabolic detoxification, decreased penetration and target site insensitivity. Resistance to pyrethroid insecticides involves a kdr -type nerve insensitivity and possibly increased oxidative detoxication. Organophosphate and carbamate resistance mechanisms include increased hydrolytic and oxidative metabolism but do not involve an altered or insensitive acetylcholinesterase. Metabolic detoxification, when identified, involves a complex of enzyme systems which act in concert to produce significant resistance levels. Resistance mechanisms identified for chlorpyrifos and propoxur indicate that different forms of both oxidative and hydrolytic enzymes are responsible for the resistance. Implications to management and cross resistance are discussed.