The relationship between hematophagy and the morphology of female tarsal claws in neotropical black flies (Simuliidae: Diptera: Insecta)

Simulids are vectors of many human diseases. The most widely known are onchocerciasis (river blindness) and mansonellosis. Black flies are also responsible for the transmission of diseases such as bovine onchocerciasis, and Eastern Equine Encephalitis (EEE) to wild and domestic animals.In some areas they have a significant economical and sanitary impact on human, cattle and poultry. The claws of the adult females are tarsal clasping structures that are used to attach to different host’s tegument. Using scanning electron microscopy, morphological differences in female tarsal claws were detected in a number of species of Neotropical black flies. This study proposes a correlation between claw morphology and the hematophagic feeding habits of blackfly females. Two types of claws were observed: simple claws with a subbasal tooth either absent or reduced in size (typically associated to mamalophilic species), and bifid claws with a basal tooth well developed and vary in shape from spatulated to subcylindric (present in ornitophilic species. A list of hematophagic species of blackflies, their hosts and the size of subbasal tooth is provided.