Long-chain free fatty acids from Momordica cochinchinensis leaves as attractants to its insect pest, Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae)

Extraction, thin layer chromatography, and gas chromatography-mass spectrometry of young, mature, and senescent leaves of Momordica cochinchinensis Spreng revealed 13 free fatty acids, representing a total of 82.29, 91.30, and 68.52% of fatty acids in young, mature, and senescent leaves, respectively. Palmitic acid was the predominant fatty acid followed by stearic acid in three types of leaves. The free fatty acids from young, mature, and senescent leaves attracted female Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) at the minimal concentrations of 4, 2, and 8 mu g, respectively; whereas the mixtures of synthetic fatty acids mimicking free fatty acids of young, mature, and senescent leaves showed attraction at the minimal concentrations of 4, 2, and 10 mu g, respectively, in Y-shaped glass tube olfactometer bioassay under laboratory condition. The results indicate that A. foveicollis may employ long-chain free fatty acids as an olfactory cue for host location. The individual synthetic fatty acids mimicking the proportions detected in three types of leaves were also evaluated through olfactometer bioassay. Only synthetic palmitic acid at the minimal amount of 2.17 mu g attracted the insect. A synthetic blend of fatty acids mimicking 8 mu g free fatty acid concentration of mature leaves or an amount of 5.42 mu g palmitic acid produced the highest attraction of the insect Hence 5.42 mu g palmitic acid might be used for insect pest management program such as baited traps. (C) 2014 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. Published by Elsevier B.V. All rights reserved.