The repellent effect of organic fatty acids on Culicoides midges as determined with suction light traps in South Africa

Abstract

The efficacy of a 15% (w/w) mixture of octanoic, nonanoic and decanoic acids in light mineral oil to repel Culicoides biting midges (Diptera; Ceratopogonidae) was determined in three replicates of a 4 x 4 Latin square design under South African field conditions. The fatty acids were applied to ±0.07 m 2 polyester meshes with a mesh size 2-3 mm fitted to 220 V 8 W Onderstepoort downdraught light traps. To reduce the relatively strong attraction of the light trap, the black light tubes in the Onderstepoort trap were replaced with 8 W 23 cm white light tubes. The traps were operatingf overnight next to cattle. Two traps treated with the mixture of fatty acids collected 1.7 times fewer midges than two untreated traps. Although this mixture of fatty acids had shown a repellent effect against a number of blood-feeding insects this is the first indication that it also has a significant repellent effect against Culicoides species and especially Culicoides (Avaritia) imicola Kieffer when applied to polyester mesh.2

African horse sickness: The potential for an outbreak in disease‐free regions and current disease control and elimination techniques

“…The use of netting and fans has also been shown to reduce blood-feeding by Culicoides on horses in various housing systems in Switzerland [120]. Use of insecticide-impregnated mesh rather than plain gauze is also likely to reduce further the entry of midges into animal housing and thereby reduce the midge attack and biting rate [119,121,122]. Insect blankets with both neck and hood covers have been shown to limit the feeding rate of Culicoides on horses in the Netherlands, and the authors of this study suggested that this might be helpful to protect horses from bites of AHS-infected Culicoides [123].…”

Efficacy of alphacypermethrin-treated high density polyethylene mesh applied to jet stalls housing horses against Culicoides biting midges in South Africa

“…The use of mesh to protect stabled horses (Barnard, 1997;Meiswinkel et al, 2000) and the efficacy of insect repellents or insecticides applied to mesh surrounding light traps against Culicoides midges have been reported (Braverman and Chizov-Ginzburg, 1998;Page et al, 2009Page et al, , 2014Venter et al, 2011Venter et al, , 2014Del Río et al, 2014a, b). In contrast to the proven efficacy (Lengeler, 2004) and extensive use of pyrethroid-treated mesh against mosquitoes, the use of similar material to protect 3 horses against Culicoides midges has received limited attention (Carpenter et al, 2008a).…”

Field and in vitro insecticidal efficacy of alphacypermethrin-treated high density polyethylene mesh against Culicoides biting midges in South Africa

“…Stabling efficacy depends on the exophilic/endophilic behaviour of the vector species (Carpenter et al, 2008;Viennet et al, 2012), and horses are protected only if the stables are adequately closed (Barnard, 1997;Meiswinkel et al, 2000). Repellents such as N,N-diethyl-3-methylbenzamide (Page et al, 2009), pyrethroids and plant extracts (Braverman and Chizov-Ginzburg, 1998), and organic fatty acids (Venter et al, 2011) have shown efficacy against Culicoides midges in light trap studies. Recently, insecticidal efficacy against colony-reared Culicoides (Monoculicoides) nubeculosus Meigen exposed to hair from horses treated with cypermethrin was reported (Papadopoulos et al, 2010).…”