Courtesy Washington State UniversityDavid CrowderOrchards and vineyards have been linked to a greater prevalence of West Nile virus in mosquitoes and the insects' ability to spread it to animals and people, according to recent Washington State University research.
The results could help cash-strapped mosquito abatement districts focus on areas that pose the greatest danger to humans and livestock, according to a news release.
David Crowder, a Washington State University entomologist, led a group that examined West Nile virus cases and how they related to different types of landscape.
Along with fellow entomologist Jeb Owen, they merged data from a variety of sources, including West Nile infections in humans, horses and birds; surveys of virus-bearing mosquitoes; breeding bird surveys' and land-use maps; and climate data from the Northwest.
The researchers found that areas with higher instances of disease in horses and birds also had significantly more mosquitoes, more American robins and more house sparrows.
Those two bird species were implicated the most in the disease's transmission.
Those same areas also had a higher prevalence of West Nile in mosquitoes.
In addition, the areas had a higher proportion of land devoted to orchards.
It's still unclear why orchards saw more West Nile, but the researchers speculate that mosquitoes are drawn to orchards for plant nectar during flower.
Robins and house sparrows are attracted to orchards for nesting and feeding.
The research was published in the journal PLOS ONE.