Insights into the genetic landscape and presence of Cochliomyia hominivorax in the Caribbean.

The New World screwworm, Cochliomyia hominivorax, is a major parasite that causes myiasis in livestock, humans, and other warm-blooded animals in the western hemisphere. There is a permanent biological border that is maintained between Panama and Colombia, as it has been eradicated from North and Central America. However, it still exists in much of the Caribbean and South America causing an estimated annual loss of $3.6 billion dollars in South America alone. Less information is available for C. hominivorax in the Caribbean. Thus, here we examined its presence and genetic landscape in order to gain insights into this fly's distribution in this region. First, through sampling efforts, novel GPS (Global Positioning System) coordinates were collected. Second, the environmental correlates of those presence points were examined. Next, samples were sequenced in order to obtain a pairwise ΦIT genetic distance matrix. And lastly, this matrix was used to create a genetic landscape of divergence. The results of the genetic landscape show flies as more diverse in Trinidad and Tobago and less diverse in the Dominican Republic. This is perhaps due to the proximity of Trinidad to Venezuela and gene flow may be occurring between these two areas. This information will aid in screwworm surveillance and control programs by providing environmental correlates and a view into the distribution of these flies.