As a relative newcomer to tabanid research I unfortunately can't help much but would also be very interested to hear responses to this one. We are currently investigating the role of tabanids and other large biting flies in the mechanical transmission of pathogens.

Tabanids female are quite opportunistic blood feeders. Horse flies mostly fed on large ungulates (horse, cattle, red deer, sometimes also wild boar). Deer flies have a larger range of hosts including large mammals, and also humans, birds and reptiles occasionnaly.

I have made some works on this topic. You can found further informations and some references in these articles.

Frederic

Baldacchino, F., Puech, L., Manon, S., Hertzog, L.R., Jay-Robert, P., 2014. Biting behaviour of Tabanidae on cattle in mountainous summer pastures, Pyrenees, France, and effects on weather variables. Bull. Entomol. Res. doi:10.1017/S0007485314000170

Baldacchino, F., Gardès, L., De Stordeur, E., Jay-Robert, P., Garros, C., 2013b. Blood-feeding patterns of horse flies in the French Pyrenees. Vet Parasitol. 199, 283-288.

Hi David

My experience of tabanids is that they are not guided to hosts in quite the same way as most other biting flies like mosquitoes, i.e. the cues are different. It is well known that because they hunt by sight that larger objects attract their attention more readily but what stimulates attraction after that is more of a puzzle. Certainly colour plays a role so darker animals are more attractive than pale ones - you can easily test this by getting two people of similar size to wear different clothing sets - one black and one white. The black clothing tends to be covered by flies while the white may have only a few.

However, having sat next to a large horsefly on a balcony overlooking a busy street in Dhaka, and having watched it watching the passers by there are obviously more complex cues as there were several juicy looking cows as well as various human offerings to select from, all of which were ignored. Sometimes variation in colour picks out targets - similar to the approach taken by tse-tse so dappling or shifting tones of light must also play a role.

When it comes to selecting between individuals clustered together apart from size and colour elements like odour obviously play a role, so individuals emitting more warmth and CO2 and VOCs seem, not surprisingly, more attractive. However, like many blood feeders they do not go straight for a feed, particularly deer flies, but settle on a different part of the surface (if it is human they settle on the clothing) and then after a while crawl to a convenient part of the skin to bite.

Don't know whether this is the sort of thing that you want to know or even if it is remotely helpful but it might be a start.

Regards, Ian

No tabanid has been found that is specific to one species of host, although some do show a marked preference for some host species over others. Such generalism in haematphagous arthropod species, as with other generalist feeders, is thought to have evolved in environments where the chances of host encounter are low and the advantage of waiting for an optimal host is traded off against the risk of death before feeding. The haematophagous members of the family are known to favour larger mammals as hosts such as cows, horses and deer. If you follow the link below, you'll find a paper providing a good introduction to the visual and odour cues used by female tabanids to locate their mammal hosts:

https://arago.elte.hu/sites/default/files/TabanidZebraOdour_PhB.pdf

One of my M.sc students is working on the Diurnal activity changes of adult Tabanus spp. (Diptera:Tabanidae) in summer and their control using the Epsilon Trap in Kaoma District, Zambia. I would appreciate receiving latest references concerning this work.

Phillip Nkunika

I would suggest that host odorants for long distance attraction (olfaction), and surface chemical compositions (contact sensory) for final decision making may play critical roles in food species selection. Of course, some other biotic factors may also involve in host selection.

Look at the website NzItrap.com for a good source of biting fly field studies with colored traps, natural and synthetic odors. I think Mary Owaga and colleagues was the source of a set of new insights with the paper on fermented (aged) ungulate urine. In addition to clues from GC-MS studies (including mine) of organic chemical volatiles, it appears that CO2, ammonia and skin -evolved moisture are essential contributors to the cloud of attractive odors surrounding living, breathing, sweating, excreting bags of blood! .

Host odorants have an attraction in the selection of blood meal. The arthropods have host preference in the selection of their blood meal. lalitha kabilan

Humidity constitutes a factor in the selection of blood meals. The blood feeding tabanids are present in environments with high humidity especially under shades like animal stalls. They are also attracted to fruit gardens [ie places with high humidity] where they thrive on fruit sellers skin and domestic animals. Fruits especially open ones with their high aromatic and moisture contents attract them to fruit gardens. In one of our recent samplings for blood sucking tabanids ,we were shocked to collect them from fruit gardens.in Port Harcourt, Nigeria.

Blood type and Rh Factor play a role in selection of blood meals. One of my favorite articles that I have applied to various blood sucking arthropods is Wood CS Preferential feeding of Anopheles gambiae mosquitoes on human subjects of Blood Group O:....Huma Biol 1974:46;385 Also Mumcuoglu, Et Al Medical and Vet Ent 2010 Effects of Blood types and blood handling on feeding success, ...in the body louse..