Avian defensive behavior and blood-feeding success of the West Nile vector mosquito, Culex pipiens

Avian defensive behavior against host-seeking arthropods influences transmission of vector-borne pathogens by affecting mosquito biting rate, either by preventing vector-host contact or by increasing the rate of multiple host feeding. We exposed house sparrows (Passer domesticus L.) and chickens (Gallus gallus domesticus L.) to Culex pipiens pipiens L. overnight in a large observation cage and measured avian defensive behavior rates and mosquito blood-feeding success. Both bird species exhibited a range of defensive behaviors, 90% of which were foot stomps, head movements, and wing shakes. Total behavior rates increased proportionately with mosquito density in both species, increased after the first hour of mosquito exposure, and decreased as individual birds were exposed to mosquitoes multiple times. Mosquito blood-feeding success on house sparrows was high overall (82 +/- 5%) and independent of behavior rates. Blood-feeding success on chicks was lower (58 +/- 5%) and negatively correlated with defensive behavior rate after the first hour of mosquito exposure. Results revealed a higher percentage of partial blood meals on chicks (18 +/- 3% of all blood meals on chicks) than on house sparrows (4.9 +/- 3%). Birds of both species ate an average of 9.4 +/- 1.2% of mosquitoes, and this percentage was positively correlated with defensive behavior. High mosquito feeding success on house sparrows supports its role as a potential amplifying host of West Nile virus.