Activity of drimane antifeedants and related compounds against aphids, and comparative biological effects and chemical reactivity of (-)- and (+)-polygodial.

A series of natural drimanes and related synthetic compounds was tested for antifeedant activity against aphids. Polygodial and warburganal were the most active. The synthetic compounds methyl 9α-hydroxydrimenoate and 9α-hydroxydrimenal, although active against lepidopteran larvae, were inactive against aphids. Natural (-)-polygodial and the synthetic (+) isomer showed similar levels of activity as aphid antifeedants and in phytotoxicity, fish toxicity, and human taste tests, but reacted at different rates with enantiomers of 1-phenylethylamine.