Vector-host interactions in avian nests: do mosquitoes prefer nestlings over adults?

Abstract

The hypothesis that nestlings are a significant driver of arbovirus transmission and amplification is based upon findings that suggest nestlings are highly susceptible to being fed upon by vector mosquitoes and to viral infection and replication. Several previous studies have suggested that nestlings are preferentially fed upon relative to adults in the nest, and other studies have reported a preference for adults over nestlings. We directly tested the feeding preference of nestling and adult birds in a natural setting, introducing mosquitoes into nesting boxes containing eastern bluebirds (Sialia sialis), collecting blood-fed mosquitoes, and matching the source of mosquito blood meals to individual birds using microsatellite markers. Neither nestlings nor adults were fed upon to an extent significantly greater than would be predicted based upon their relative abundance in the nests, although feeding upon mothers decreased as the age of the nestlings increased.

Figure 1.

Eastern bluebird nest box with apparatus for introducing mosquitoes. The apparatus consisted of a plastic chamber (containing the mosquitoes), which fits into a plastic funnel inserted into the entrance hole of the best box.

Figure 2.

Proportion of mosquitoes introduced into eastern bluebird (Sialia sialis) nest boxes with mother and nestling birds (of different ages) that fed on the mother bird, Auburn, Alabama, 2008 and 2009.

Figure 3.

Proportion of mosquitoes introduced into eastern bluebird (Sialia sialis) nest boxes, which successfully obtained a blood meal, over a range of nestling ages, Auburn, Alabama, 2008 and 2009.

Figure 4.

Mother bluebird brooding two-day-old nestlings.