Species Identification of Ovine-Feeding Mosquitoes in Southwestern Montana

Abstract

In order to contribute to research on Cache Valley Virus, an ovine virus that leads to fetus malformations and abortion, this study investigated the specific species of mosquitoes that blood feed on domestic sheep. Nine sheep were separated into three groups and were contained in a constructed trap one night per week for seven weeks (July-August 2011) in a rural area in southwestern Montana. Mosquitoes that entered the sheep-baited trap during the evening were then collected for species identification and bloodfed status the following morning. This study also examined the effectiveness of two different insecticide treatments. The three groups of sheep consisted of a control group, a group with Python insecticide ear tags, and a group with a permethrin pour-on. Bloodfed mosquitoes were found in each of the 16 mosquito species collected from the sheep-baited traps. The species collected from the sheep-baited traps were then compared to species collected from a CDC light trap located near the study site. The data collected from this study showed that in the sheep-baited traps Ochlerotatus increpitus, Ochlerotatus idahoensis, and Aedes vexans were the three most prevalent species; Ochlerotatus dorsalis, Aedes vexans, and Ochlerotatus idahoensis were the three most prevalent species in the light trap collections. Furthermore, Cs. inornata, Oc. intrudens, Oc. sierrensis, Oc. implicatus are potential reservoirs of CVV because they were present only in the sheep-baited traps. These results help to direct further investigations of potential vectors for Cache Valley Virus in Montana.