Penetration, Excretion, and Metabolism of Carbaryl in Susceptible and Resistant German Cockroaches1

Abstract

Carbaryl metabolism was compared between susceptible and resistant, Blattella germanica (L.). Rates of penetration, excretion, and metabolism and nature of metabolites were determined at various time intervals after topical application of known amounts of carbaryl. Both susceptible and resistant cockroaches degraded carbaryl to 1-naphthol and 1-naphthol conjugates. Other unidentified metabolites were detected in minute quantities. Penetration of carbaryl was slower, less carbaryl was retained in the tissues, and more carbaryl was excreted in the resistant cockroaches. Slightly larger amounts of internal and excreted 1-naphthol were found in the susceptible cockroaches but more conjugated 1-naphthol was recovered from resistant cockroaches. It is hypothesized that more rapid hydrolysis of carbaryl to 1-naphthol and subsequent conjugation play an important role in the carbonyl-resistance. Slower penetration and more rapid excretion of carbonyl in the resistant cockroaches may be minor contributing factors to the resistance.