Keds, the enigmatic flies and their role as vectors of pathogens

Hippoboscid flies (Diptera: Hippoboscidae), commonly known as keds or louse flies, have been for long time overlooked by the scientific community, and their vector role of infectious agents to humans and domestic animals has been scantly investigated. This is partly due to the fact that the host range for most species is primarily restricted to wildlife, being rarely reported on domestic animals and humans. This led to a scarce scientific knowledge about their biology, ecology, behaviour, epidemiology as well as vector competence. However, the life history of some hippoboscid species, e.g., Melophagus ovinus, Lipoptena cervi and Hippobosca equina, suggests that these ectoparasites are important candidates to vector infectious disease agents (e.g., Rickettsia spp., Borrelia spp., Bartonella spp., Anaplasma phagocytophilum, Theileria ovis). Indeed, the peculiar biological and behavioural traits (i.e., obligatory blood sucking and reproductive physiology) of many ked species make them a suitable pabulum for pathogen's multiplication and for their transmission to receptive hosts. Therefore, studies focusing on the ked bio-ecological aspects as well as on their vector role are advocated along with the control of keds affecting different animal species. This review discusses current information on keds, highlighting their importance as vectors of pathogens of medical and veterinary concern to all animal species, with a special focus on mammals.

Molecular evidence of bacteria in Melophagus ovinus sheep keds and Hippobosca equina forest flies collected from sheep and horses in northeastern Algeria

The sheep ked, Melophagus ovinus, and the forest fly, Hippobosca equina, are parasitic dipteran insects of veterinary importance. As hematophagous insects, they might be considered as potential vectors of diseases which may be transmissible to humans and animals. The purpose of this study was to present initial primary data about these two species in Algeria. To do so, we conducted a molecular survey to detect the presence of bacterial DNA in flies collected in Algeria. A total of 712 flies including, 683 Melophagus ovinus and 29 Hippobosca equina were collected from two regions in northeastern Algeria. Monitoring the monthly kinetics of M. ovinus infestations showed something resembling annual activity, with a high prevalence in January (21.67%) and May (20.94%). Real-time quantitative PCR assays showed that for 311 tested flies, 126 were positive for the Bartonella spp. rRNA intergenic spacer gene and 77 were positive for Anaplasmataceae. A random selection of positive samples was submitted for sequencing. The DNA of Bartonella chomelii and Bartonella melophagi were amplified in, respectively, five and four H. equina. 25 M. ovinus positive samples were infected by Bartonella melophagi. Amplification and sequencing of the Anaplasma spp. 23S rRNA gene revealed that both species were infected by Wolbachia sp. which had previously been detected in Cimex lectularius bed bugs. Overall, this study expanded knowledge about bacteria present in parasitic flies of domestic animals in Algeria.

Ultrastructural investigation of antennae in three cutaneous myiasis flies: Melophagus ovinus, Hippobosca equina, and Hippobosca longipennis (Diptera: Hippoboscidae)

Melophagus ovinus (Linnaeus 1758), Hippobosca equina Linnaeus, 1758, and Hippobosca longipennis Fabricius, 1805 (Diptera: Hippoboscidae) are economically and medically important ectoparasites that can act as mechanic vectors of pathogens and cause myiasis in both human and domestic animals. As essential olfactory organs, antennae of these adult hippoboscids were examined using stereoscopic and scanning electron microscopes. General morphology of the antenna is provided in detail, combined with distribution, types, size, and ultrastructures of antennal sensilla. On the antennal funiculus, two types of sensilla are observed, including basiconic sensilla and coeloconic sensilla. Four common characters are shared among the three species: (1) the scape is either obsolete or fused with the fronto-clypeus; (2) branched antennal structures (branched pedicellar microtrichiae and branched arista with only one segment) are detected; (3) the enlarged antennal pedicel completely envelops the antennal funiculus; and (4) less types of sensilla on funiculus. Disparity and diversity of the antennal and sensory structures are analyzed from the phylogenetic and functional perspective. We suggest that hippoboscids are potential model for the study of the function of coeloconic sensilla in Calyptratae.