Field evaluation of CDC gravid trap attractants to primary West Nile virus vectors, Culex mosquitoes in New York State.

A field study was conducted to evaluate two CDC gravid trap attractants available for the West Nile virus surveillance program in New York State (NYS). According to potential attractiveness, a common lawn sod in NYS, Kentucky bluegrass (Poa pratensis) infusion and a rabbit chow infusion were compared for attractiveness to primary West Nile virus vectors, Culex mosquitoes. Attractiveness of each infusion was measured by the number of adult mosquitoes caught in CDC gravid traps and the number of egg rafts laid in ovitraps. Both gravid trap and ovitrap studies demonstrated that lawn sod infusion with a 7-day incubation period had better attractiveness to Culex restuans/Culex pipiens than rabbit chow infusion with the same incubation period. Attractiveness of lawn sod infusions was increased as they became aged within a week's period. Lawn sod infusion also attracted more Ochlerotatus japonicus, a potentially important West Nile virus vector in New York.