title: Field and in vitro insecticidal efficacy of alphacypermethrin-treated high density polyethylene mesh against Culicoides biting midges in South Africa.
abstract: The efficacy of untreated and alphacypermethrin-treated high density polyethylene (HDPE) mesh against Culicoides biting midges (Diptera: Ceratopogonidae) was determined using Onderstepoort downdraught black light traps and a contact bioassay. Three traps were operated overnight in four replicates of a 3×3 randomised Latin square design near horses under South African field conditions. Both the untreated and alphacypermethrin-treated HDPE mesh significantly (P<0.05) reduced the numbers of Culicoides midges, predominantly Culicoides (Avaritia) imicola Kieffer, collected in the light traps by 4.2 and 7.2 times, respectively. A repellent effect of the alphacypermethrin-treated mesh was not confirmed because the number of midges collected in the light traps with untreated and alphacypermethrin-treated HDPE mesh was not significantly different (P=0.656). Bioassay of the insecticidal contact efficacy indicated median C. imicola mortality of 100% from 30 and 10 min following exposure to the alphacypermethrin-treated HDPE mesh for 1 or 3 min, respectively. In the bioassay, mortality was significantly higher (P=0.016) at 5 min post exposure in the midges exposed to the alphacypermethrin-treated mesh for 3 min (74.8%) compared to the 1 min exposure group (59.5%). The HDPE mesh could be used to reduce exposure of housed animals to Culicoides midges, specifically C. imicola, and viruses transmitted by these midges. Mesh treated with alphacypermethrin had the additional benefit of a rapid insecticidal effect on C. imicola.
authors.affiliation: Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa. Electronic address: patrick.page@up.ac.za.
authors.forename: P C
authors.initials: PC
authors.lastname: Page
authors.affiliation: PVVD, ARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort 0110, South Africa.
authors.forename: K
authors.initials: K
authors.lastname: Labuschagne
authors.affiliation: PVVD, ARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort 0110, South Africa.
authors.forename: G J
authors.initials: GJ
authors.lastname: Venter
authors.affiliation: Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
authors.forename: J P
authors.initials: JP
authors.lastname: Schoeman
authors.affiliation: Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
authors.forename: A J
authors.initials: AJ
authors.lastname: Guthrie
mesh_terms: D000818:Animals; D002519:Ceratopogonidae; D006736:Horses; D007300:Insect Control / Q000295:instrumentation*; D007303:Insect Vectors; D007306:Insecticides; D057147:Mosquito Nets / Q000592:standards; D020959:Polyethylene; D011722:Pyrethrins; D013019:South Africa
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin; D020959:Polyethylene
keywords: African horse sickness; C. imicola; Contact bioassay; Light trap; Synthetic pyrethroid