Alkylfurans:  Effects of Alkyl Side-Chain Length on Insecticidal Activity

The insecticidal activity of five alkylfurans against the generalist insect herbivore beet armyworm, Spodoptera exigua, was examined. Two naturally occurring compounds, the avocadofurans 2-(pentadecyl)furan (<BO>1</BO>) and 2-(heptadecyl)furan (<BO>2</BO>), previously isolated from specialized avocado idioblast oil cells, and three homologues, 2-(tetradecyl)furan (<BO>3</BO>), 2-(hexadecyl)furan (<BO>4</BO>), and 2-(octadecyl)furan (<BO>5</BO>), were synthesized. Bioassays of alkylfurans <BO>1</BO>−<BO>5</BO> using a 9-day diet-incorporation initiated with neonates showed that all alkylfurans tested significantly increased S. exigua larval mortality and reduced larval weights, with maximal biological activity detected among the naturally occurring alkylfurans <BO>1</BO> and <BO>2</BO>.