torsdag 4 februari 2010
Why do tabanids attack black horses?
In a recent paper published in Proceedings of the Royal Society of London B (Horváth et al. 2010; http://rspb.royalsocietypublishing.org/content/early/2010/01/28/rspb.2009.2202.full.html#ref-list-1) we report on why dark (black and brown) horses suffer from more attacks from blood sucking tabanids (horse flies) compared to white horses. The reason is that the dark coat of the horse reflects polarized light from the sky in a way much similar to a water surface. The blood sucking tabanids are attracted to water to drink and to lay their eggs, and use information from reflected polarized light also to locate hosts. It is the female tabanids that are attracted to the host to suck blood, and use this meal to produce eggs. Tabanid attacks can be severe and cause spreading of diseases to humans and grazing animals as well as reduce milk production in cattle. What we can learn from this is that we shall dress in white cloths and avoid dark, black clothing when in the field, especially when visiting wet areas with high numbers of tabanid flies.