Factors affecting blood feeding patterns of Culex mosquitoes: Studies of host-seeking patterns, avian anti-mosquito defensive behavior and host disease.

摘要

West Nile virus (WNV) was first detected in North American in 1999. By 2004 it had spread throughout the continental United States. Its rapid expansion is due in part to a wide variety of potential mosquito vectors and avian reservoir hosts. No human vaccine is yet available, so vector and virus surveillance are critical for disease prevention. The wide host range of WNV therefore presents a problem to public health officials, who must detect enzootic transmission foci to localize mosquito control efforts. Unfortunately, little is known about the dynamics of mosquito-bird interactions in nature. In my research, I have investigated what factors affect mosquito host-seeking patterns, how variation in avian anti-mosquito defensive behavior, including that caused by host disease, affects mosquito blood-feeding success.; Sentinel chickens, a method of early WNV or other arbovirus detection, in New York state (NYS) were discontinued in 2000 because they failed to detect virus prior to human cases. To see if WNV vectors in NYS preferred passerine birds in the tree canopy over sentinel chickens near the ground, I captured mosquitoes in chick- and house sparrow-baited traps at two heights in 2003--2004. Although Culex vectors showed no bait species preference, Cx. restuans preferred to feed in the canopy, a result which may improve vector surveillance.; Heterogeneity in host feeding patterns can lead to 20% of a host population contributing to up to 80% of pathogen transmission. I exposed birds to mosquitoes to see if heterogeneity in defensive behavior contributed to variation in host feeding patterns. I observed high mosquito feeding success regardless of house sparrow behavioral intensity, suggesting they are fed upon readily in nature. I found a similar pattern in older chickens, but more defensive younger chicks seemed to reduce mosquito feeding success.; To see if host disease affects mosquito feeding success by suppressing defensive behavior, I exposed pairs of house finches (Carpodacus mexicanus ) to mosquitoes before and after one finch was inoculated with the pathogen Mycoplasma gallisepticum. I found that disease diminished rates of defensive behavior in sick finches, but finches were fed upon less frequently when they were sick.