Determining host selection of the stable fly, Stomoxys calcitrans (Linnaeus 1758), using molecular analysis of blood meals

The stable fly, Stomoxys calcitrans (Linnaeus 1758), is an important pest of many animals worldwide, particularly canids and large ungulates. These blood-feeding dipterans are of African origin and have a negative economic effect on domesticated livestock and wildlife systems. It is estimated that stable flies cost US cattle producers $2 billion per year, as cattle are the primary hosts in agricultural settings. It is unknown how the behavior or feeding patterns of this fly might change when presented with other host options, particularly exotics, including those found in its native African range. To address this question, we used molecular tools to examine host blood meals from stable flies collected at a drive-through safari park in Bryan, Texas. The park was divided into eight collection zones: three drive-through pastures with various species of birds and hoofed mammals, a zebra pasture, a quarantine/holding paddock area, and three walk-around zoo areas containing a wider variety of animals. Flies were collected weekly from May of 2022 to May of 2023, and DNA was extracted from whole fly specimens collected across these zones. These DNA templates were used in a PCR assay targeting the vertebrate mitochondrial 16S gene. Resulting amplicons were submitted for Sanger sequencing and compared to publicly available data (NCBI) using BLAST. Searches indicated that the stable flies fed on a variety of hosts including but not limited to Bos grunniens (yak), Bos taurus (cattle), Cervus canadensis (elk), Elaphurus davidianus (Père David’s deer), and Homo sapiens (human).