Comparative effects of cattle, horse, and chicken blood on stable fly (Stomoxys calcitrans (L.)) fecundity

The hematophagous stable fly (Stomoxys calcitrans (L.)) is a cosmopolitan pest that can cause decreased weight gains in confined and pastured cattle. While S. calcitrans readily feeds on domestic livestock, most companion animals, and humans, this species rarely feeds on birds. The inability of stable flies to successfully mate when fed chicken blood has been presumed to be due to a protein deficiency in avian blood that is not absent in mammalian blood. During a West Nile virus outbreak in a colony of American white pelicans ((Pelecanus erythrorhynchos Gmelin) in northeast Montana, stable flies fed on moribund pelicans at a level that has not been previously documented with any other avian species. Given the novelty of this behavior, the objective of this investigation was to evaluate stable fly daily and lifetime fecundity rates when fed cattle, horse, or chicken blood. Each treatment was replicated three times. Lifetime fecundity rates between treatments were similar (χ2=3.4; df=2; P=0.2). Daily fecundity rates were highest for flies fed chicken blood (vs. cattle: P=0.008; vs. horse: P=0.05), but oviposition periods were shorter. Eggs deposited by females fed chicken blood had a smaller volume than those produced by the other cohorts (F=16.6; df=2, 333; P < 0.001). Egg viability did not significantly differ between treatments. These results, in conjunction with field observations, suggest that stable fly-host interactions may be influenced by host defensive behaviors rather than host blood suitability.