Interrupted blood-feeding by Culiseta melanura (Diptera: Culicidae) on European starlings.

ABSTRACT

To determine whether Culiseta melanura (Coquillett) mosquitoes tend to take multiple blood meals when birds of certain species serve as hosts, we compared the frequencies with which such mosquitoes fed upon caged starlings and robins and determined whether similar volumes of blood were imbibed from each. The blood of robins (Turdus migratorius) and European starlings (Sturnus vulgaris) was marked contrastingly by injecting birds with rubidium or cesium salts. Caged birds were placed together in a natural wetland setting overnight. Mosquitoes captured nearby on the following morning were analyzed for each of the elemental markers. Where marked robins and starlings were equally abundant, 43% of freshly engorged Cs. melanura fed on more than or equal to two hosts. More Cs. melanura fed on robins than on starlings. Individual mosquitoes tended to contain far more robin- than starling-associated marker, indicating that mosquitoes "feasted" on robins but only "nibbled" on starlings. Mosquitoes marked with both elements apparently fed meagerly on the starlings then abundantly on the robins. Our estimates of bloodmeal volume indicate that 85% of mosquitoes that fed on marked starlings obtained < 0.5 microliter of blood from them. We suggest that defensive behavior by starlings interrupts mosquito blood-feeding and that, in a communal roost of starlings, each mosquito will tend to feed on more than one bird, thereby promoting rapid transmission of such ornithonotic arboviruses as eastern equine encephalomyelitis virus and West Nile virus.