Latitude and the Duration of Neartic WNV Outbreaks

描述（由申请人提供）：我们试图探索西尼罗河病毒（WNV）在美国北方的传播力可能大于中纬度地区的假设。为此，我们将确定是否库蚊的繁殖季节的持续时间pipiens，蚊子，作为主要的维护载体，在这个地区，与纬度相关，以及是否白天长度限制了吸血和随后的生殖活动的持续时间。首先（1），我们将确定自然界中这些蚊子产卵和寄主探索活动的季节动态。(1.1)产卵活动将进行分析，记录丰富的蛋筏沉积在采样装置从4月至10月在选定的网站沿着一个横断面范围从34度N到45度N沿着美国东海岸。(1.2)马萨诸塞州波士顿附近吸血活动的季节性将通过在鸟饵猪油罐陷阱中对蚊子进行采样来确定。C.用这些装置捕获的尖音蚊会被鉴定和解剖，以确定它们是否已分娩，以及它们的卵巢是否处于滞育状态。我们将（1.3）确定这些C。在卵巢滞育开始后，尖音蚊继续寻找宿主，试图将它们收集在定期设置在大冬眠室中的鸟饵猪油罐陷阱中，在那里记录它们的生殖行为和寿命。一系列补充实验室观察（1.4）将试图确定在不同纬度收集的蚊子后代是否对相似的昼夜节律作出反应而进入和离开卵巢滞育，或者来自中纬度的蚊子是否比来自更北地点的蚊子在更短的昼夜节律中滞育。接下来（2），实验室实验将试图确定卵巢发育和寄主寻找行为是否受到类似环境线索的调节。最后，将探讨库蚊种群结构在南北轴上比东西轴上更明显的可能性（3）。微卫星、RAPD和SSCP标记将从沿着我们的南北样带以及800公里范围内的其他样带采样的蚊子中进行分析。将研究近交自体群体的存在。总之，这些观察结果将确定这些病媒蚊子可能在美国北方扩增WNV的持续时间，并将确定该时间段是否与白天长度或环境温度相关。

DESCRIPTION (provided by the applicant): We seek to explore the hypothesis that the force of transmission of West Nile virus (WNv) may be greater in the northern United States than in more central latitudes. Toward this end, we shall determine whether the duration of the breeding season of Culex p. pipiens, the mosquitoes that serve as the main maintenance vectors of WNv in this region, correlates with latitude and whether day-length limits the duration of blood-feeding and subsequent reproductive activity. First (1), we shall define the seasonal dynamics of oviposition and host-questing activity of these mosquitoes in nature. (1.1) Oviposition activity will be analyzed by recording the abundance of egg-rafts deposited in sampling devices from April through October in selected sites along a transect ranging from 34 degrees N to 45 degrees N along the east coast of the US. (1.2) The seasonality of blood-feeding activity near Boston, MA will be defined by sampling mosquitoes in bird-baited lard-can traps. C. pipiens mosquitoes captured in these devices will be identified and dissected to determine whether they are parous and whether their ovaries may be in diapause. We shall (1.3) determine whether these C. pipiens mosquitoes continue to seek hosts after ovarian diapause has commenced by attempting to collect them in bird-baited lard-can traps set periodically in large hibernacula where their reproductive behavior and longevity will be recorded. A series of complementary laboratory observations (1.4) will seek to determine whether the progeny of mosquitoes collected at different latitudes enter and leave ovarian diapause in response to similar diels or whether mosquitoes from the middle latitudes diapause at a shorter diel than those from more northerly sites. Next (2), laboratory experiments will seek to determine whether ovarian development and host-questing behavior are regulated by similar environmental cues. Finally, the possibility (3) that Culex populations may be structured more distinctly on a north-south than an east-west axis will be explored. Microsatellite, RAPD and SSCP markers will be analyzed from mosquitoes sampled along our north-south transect as well as others sampled within an 800 km space. The presence of inbreeding autogenous populations will be investigated. Taken together, these observations will define the duration of the period during which these vector mosquitoes may amplify WNv on the Northern U.S. and will determine whether that period correlates with day length or with ambient temperature.