The relationship between feeding specialization and host plants to aldrin epoxidase activities of midgut homogenates in larval Lepidoptera

Abstract. 1. Aldrin epoxidase activities of midgut homogenates in fifty‐eight species of phytophagous lepidopterous larvae, were determined. 2. There were no significant differences in mean activities amongst monophagous, oligophagous and polyphagous feeders. These results question the widely held view that there is a correlation between mixed function oxidase activity and feeding specialization. 3. Aldrin epoxidase activity depended largely on the host which was consumed. Larvae with high activity invariably fed on hosts containing monoterpene compounds. 4. The proposal that mixed function oxidases provide polyphagous insects with an effective biochemical defence against diverse allelochemicals is discussed.