Inhibition of chitin metabolism by avermectin in susceptible organisms.

Avermectin inhibits Mucor miehei and Artemia salina chitin synthesis and to a degree DNA synthesis in the former. The antibiotic interferes with chitin turnover in brine shrimp and inhibits Streptomyces antibioticus chitinase activity in vitro. In light of the proposed mode of action of avermectin and the anomolies in the literature, it is proposed that avermectin can kill susceptible organisms not only by a neurotoxic mechanism but also by inhibiting chitin turnover and synthesis at low concentration and thus the molting/ecdysis process.