Spatial repellency, antifeedant activity and toxicity of three medium chain fatty acids and their methyl esters of coconut fatty acid against stable flies

Abstract

BACKGROUND Stable flies are one of the most detrimental arthropod pests to livestock. With changing climates and agronomic practices, they expand their roles as pests and disease vectors as well. Their painful bites reduce livestock productivity, annoy companion animals, and interfere with human recreational activities. Current management technologies are unable to effectively control stable flies. The present study reports new results concerning the contact, spatial repellency, and toxicity of a bio-based product, coconut fatty acid and their methyl ester derivatives of free fatty acids of C-8:0, C-10:0 and C-12:0 to stable flies. RESULTS Three medium chain fatty acid methyl esters (C-8:0, C-10:0 and C-12:0) showed strong antifeedant activity against stable flies and their strengths were dose-dependent. Only the C-8:0 acid, C-8:0- and C-10:0 methyl esters elicited significant antennal responses. Laboratory single cage olfactometer bioassays revealed that coconut fatty acid and C-8:0 methyl ester displayed active spatial repellency. All three methyl esters showed strong toxicity against stable flies. CONCLUSION Antifeedant activity is the main method through which coconut fatty acid deters stable fly blood-feeding. The C-8:0, C-10:0 and C-12:0 methyl esters act not only as strong antifeedants, but also possess strong toxicity against stable fly adults. Limited spatial repellency was observed from coconut fatty acid and C-8:0 methyl ester. (c) 2019 Society of Chemical Industry