Distribution of Culicoides sonorensis (Diptera: Ceratopogonidae) in Alberta, Canada

The distribution of Culicoides sonorensis Wirth and Jones was examined in Alberta, Canada. Sampling was conducted weekly using blacklight traps at eight locations in 2009, and 10 locations during 2010-2012. Nine supplemental sites were sampled twice annually during both 2011 and 2012. Abundance of C. sonorensis was consistently greatest at a site near the U.S. border, and declined in a northerly direction. Mean annual abundance at this site ranged from 6.4- to > 1,000-fold greater across positive sites. Data from a less extensive survey conducted during 2002-2006 were included in the remaining analyses. C. sonorensis was distributed below a diagonal spanning 49 degrees 30' N, 113 degrees 0' W to 51 degrees 21' N, 110 degrees 40' W. The relationship between the proportion of weekly samples positive and mean annual abundance at a site was determined and indicated that the proportion of positive samples could be used as a surrogate measure of abundance to overcome issues associated with the extreme variation in abundance. A series of logistic regression models were developed and evaluated to determine the effects of spatial (latitude and longitude), climatic (historic temperature and precipitation during the warmest quarter), and weather (temperature during the sample interval and spring precipitation) on abundance as measured by the proportion of positive samples. Spatial and climatic variables set the overall level of abundance, while weather variables added seasonal fluctuations within years, and also fluctuations between years. These data will be useful for long-term monitoring of C. sonorensis and as a baseline for detecting shifts in abundance that might occur because of climate change.