Relevant Brachycera (Excluding Oestroidea) for Horses in Veterinary Medicine: A Systematic Review

Abstract

In equine stables and their surroundings, a large number of insects are present that can be a nuisance to their equine hosts. Previous studies about dipterans transmitting infectious agents to Equidae have largely focused on Nematocera. For the preparation of this systematic review, the existing literature (until February 2022) was systematically screened for various infectious agents transmitted to Equidae via insects of the suborder Brachycera, including Tabanidae, Muscidae, Glossinidae and Hippoboscidae, acting as pests or potential vectors. The PRISMA statement 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for systematic reviews were followed. The two concepts, Brachycera and Equidae, were combined for the search that was carried out in three languages (English, German and French) using four different search engines. In total, 38 articles investigating Brachycera as vectors for viral, bacterial and parasitic infections or as pests of equids were identified. Only 7 of the 14 investigated pathogens in the 38 reports extracted from the literature were shown to be transmitted by Brachycera. This review clearly shows that further studies are needed to investigate the role of Brachycera as vectors for pathogens relevant to equine health.

Keywords: Brachycera; Diptera; Equidae; equids; fly; transmission; vector.

Figure 1

PRISMA 2020 flow diagram for new systematic reviews which include searches of databases, registers and other sources, visualizing the literature research.

Figure 2

(A) Retrieved locations (regions) where studies on Brachycera in relation to their equine hosts were performed. Either flies were screened for pathogens, screened as pests for equids or transmission studies were executed [16,24,36,51,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84] (transmission studies using laboratory bred flies were not included). (B) Enlarged window from Figure 7A. Retrieved locations (regions) in Europe and Middle East where studies on Brachycera in relation to their equine hosts were performed. Either flies were screened for pathogens, screened as pests for equids or transmission studies were executed [16,24,36,51,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84] (transmission studies using laboratory bred flies were not included).

Figure 2

(A) Retrieved locations (regions) where studies on Brachycera in relation to their equine hosts were performed. Either flies were screened for pathogens, screened as pests for equids or transmission studies were executed [16,24,36,51,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84] (transmission studies using laboratory bred flies were not included). (B) Enlarged window from Figure 7A. Retrieved locations (regions) in Europe and Middle East where studies on Brachycera in relation to their equine hosts were performed. Either flies were screened for pathogens, screened as pests for equids or transmission studies were executed [16,24,36,51,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84] (transmission studies using laboratory bred flies were not included).

Figure 3

Chrysops sp. (9 to 10 mm body length) in lateral view.

Figure 4

Stomoxys calcitrans (five to seven millimeter (mm) body length) in a lateral view.

Figure 5

The head of Stomoxys calcitrans with the piercing and sucking mouthpart.

Figure 6

Musca domestica (six to seven mm body length) in a lateral view.

Figure 7

Hippobosca equina (seven to nine mm body length) in a dorsal view.