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 oc curring compounds, the avocadofurans 2-(pentadecyl)furan (1) and 2-(heptade cyl)furan (2), previously isolated from specialized avocado idioblast oil c ells, and three homologues, 2-(tetradecyl)furan (3), 2-(hexadecyl)furan (4) , and 2-(octadecyl)furan (5), were synthesized. Bioassays of alkylfurans 1- 5 using a 9-day diet-incorporation initiated with neonates showed that all alkylfurans tested significantly increased S. exigua larval mortality and r educed larval weights, with maximal biological activity detected among the naturally occurring alkylfurans 1 and 2.