Repellent and antifeedant activity of salicylic acid and related compoundsagainst the biting midge, Culicoides impunctatus (Diptera : Ceratopogonidae)

An artificial membrane, blood-feeding method was used to assess the repelle nt and antifeedant effects of derivatives of salicylic acid on the biting m idge Culicoides impunctatus Goetghebeur. Trans-2-hydroxycyclohexanecarboxyl ic acid, 6-methylsalicylic acid, 2,6-dihyrodxy-4-methylbenzoic acid, and sa licyluric acid caused highly significant inhibition of feeding, with salicy luric acid performing significantly greater than the other compounds. Inves tigating the effects of alkyl substitution of salicylic acid, o-thymotic an d o-cresotic acids were also effective. A pilot clinical trial using salicy luric acid indicated that it provided a protective effect and it was hypoth esized that this may have resulted primarily from contact, because no signi ficant repellent effects were shown for this compound in a microscope slide test, designed to demonstrate repellency with volatile compounds.