Long-Chain Free Fatty Acids from Sunflower (Asteraceae) Leaves: Allelochemicals for Host Location by the Arctiid Moth,Diacrisia casignetumKollar (Lepidoptera: Arctiidae)

Abstract

Extraction, thin layer chromatography and gas chromatography-mass spectroscopy analyses revealed 13 free fatty acids in young, mature, and senescent leaves of Helianthus annuus L. (Asteraceae) representing 75.65, 75.38, and 68.01% of total free fatty acids, respectively. α-Linolenic acid, linoleic acid, and linoleic acid were the major free fatty acids in young, mature, and senescent leaves, accounting for 22.71, 31.48, and 30.60%, respectively. The free fatty acids from young, mature, and senescent leaves attracted the female insect, Diacrisia casignetum Kollar (Lepidoptera: Arctiidae) at minimal concentrations of 12.5, 12.5, and 25 µg, respectively; whereas the synthetic mixtures of fatty acids mimicking free fatty acids of young, mature, and senescent leaves attracted at minimal concentrations of 12.5, 12.5, and 50 µg, respectively. Diacrisia casignetum insects showed attraction toward an initial amount of individual synthetic palmitic, palmitoleic, stearic, oleic, linoleic, and α-linolenic acids at 2.39, 4.63, 2.28, 3.08, 29.20, and 25.20 µg, respectively. A synthetic blend of 2.39, 4.90, 4.53, 3.14, 43, and 25.20 µg of palmitic, palmitoleic, stearic, oleic, linoleic, and α-linolenic acids, respectively, the proportion present at 100 µg concentration free fatty acids of mature leaves produced highest attractions for D. casignetum and might be used for insect pest management programme such as baited traps.