title: Trap placement and attractant choice affect capture and create sex and parity biases in collections of the biting midge, Culicoides sonorensis.
abstract: Culicoides sonorensis Wirth & Jones (Diptera: Ceratopogonidae) is the primary North American vector of bluetongue virus (BTV), which can cause high morbidity and mortality in ruminant livestock or wildlife. Worldwide, most Culicoides surveillance relies on light (usually UV) traps typically placed near animals or larval development sites. However, the trapping method can cause sex, species and parity biases in collections. We collected C. sonorensis from three dairies in California using suction traps baited with CO2 , UV light or CO2  + UV placed near animals, wastewater ponds, or in fields. Higher numbers of parous females were collected using CO2  + UV traps, although this difference was only significant on one dairy. UV traps were poor at collecting nulliparous females, but the addition of UV to a trap increased the abundance of males in a collection. Traps set in open fields collected significantly higher numbers of males and females than in either of the other two locations. In some cases, there was a significant interaction between the trap type and site. We discuss the limitations of traditional trapping methodologies for C. sonorensis and make suggestions for vector surveillance.
authors.affiliation: Department of Entomology, University of California, Riverside, CA, U.S.A.
authors.forename: E G
authors.initials: EG
authors.lastname: McDermott
authors.affiliation: Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO, U.S.A.
authors.forename: C E
authors.initials: CE
authors.lastname: Mayo
authors.affiliation: Department of Entomology, University of California, Riverside, CA, U.S.A.
authors.forename: A C
authors.initials: AC
authors.lastname: Gerry
authors.affiliation: Department of Entomology, University of California, Riverside, CA, U.S.A.
authors.forename: B A
authors.initials: BA
authors.lastname: Mullens
mesh_terms: D000818:Animals; D002140:California; D002245:Carbon Dioxide / Q000494:pharmacology; D002519:Ceratopogonidae / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D002633:Chemotaxis; D000072480:Farms; D005260:Female; D007300:Insect Control / Q000379:methods*; D008297:Male; D000071444:Phototaxis; D012098:Reproduction; D012744:Sex Ratio; D014466:Ultraviolet Rays
chemical_list: D002245:Carbon Dioxide
keywords: Culicoides sonorensis; biting midge; bluetongue virus; carbon dioxide; trapping; ultraviolet light; vector surveillance