Écologie des stomoxes (Diptera : Muscidae) au Gabon. II. Origine des repas de sang et conséquences épidémiologiques

Abstract

Summary : ECOLOGY OF STOMOXYINE FLIES (DIPTERA: MUSCIDAE) IN GABON. II. BLOOD MEALS ANALYSIS AND EPIDEMIOLOGIC CONSEQUENCESTo determine the origin of stomoxyine fly bloodmeals (Diptera: Muscidae) in Gabon, 1,021 flies belonging to seven different species of Stomoxys were captured and dissected in the area of Makokou. In total, 798 were not blood-fed and 223 bloodmeals could be gathered on filter paper. The identification of the origin of these meals was made by amplification of mitochondrial Cytb gene, then heteroduplex technique by using the Gambian rat (Cricetomys gambianus) as driver. Samples of fauna, collected on the local market, consisted of 24 mammal and two reptile blood and muscle samples, to which it is necessary to add human samples (27 potential hosts). 19 meals could not be amplified for technical reasons, 65 were amplified, but the acquired patterns corresponded to none of the tested potential hosts. On the 139 identified meals, 55 % were taken on the black-fronted duiker (Cephalophus nigrifrons) and 19 % on pig. Stomoxys transvittatus, the most abundant species in Makokou, is very opportunistic: 68 % of meals were taken on six different hosts, among whom 48 % on the black-fronted duiker and 32 % were not identified using the panel of tested hosts. S. xanthomelas took 50 % of its meals on the moustached monkey (Cercopithecus cephus) and 7 % on human beings. S. calcitrans, species of anthropised areas, took 33 % of its meals on human beings. These three species can therefore take bloodmeals on wild fauna and human beings. They could potentially play an important role in the emergence of zoonotic diseases. The four other species took their bloodmeals only on wild fauna and pig, the only example of domestic fauna in this study. This preliminary study must be followed up using a larger number of specimens and by increasing the diversity of the tested potential hosts. Résumé

Tracking zoonotic pathogens using blood-sucking flies as 'flying syringes'

“…Concerning the method efficiency, 30% of blood meals were obtained from 4099 hematophagous flies. This result is consistent with previous studies (Mavoungou et al, 2008;Simo et al, 2012) showing that most hematophagous flies caught using traps are often seeking hosts for a blood meal. Other methods using a dip net seem to have a better capture efficiency with more than 40% of engorged flies caught on their resting places (Gouteux et al, 1984).…”

“…Additionally, the lack of engorged stomoxids and tabanids could be explained by the fact that we sampled flies only at floor level. Indeed, some stomoxid species readily feed on arboreal monkeys that are mostly found higher in the tree layer (Mavoungou et al, 2008). The low rate (35%) of blood meal identifications could be explained by the degradation of host DNA during digestion in the fly midgut or by a too small blood quantity in the midgut.…”

“…As mentioned above, this result is potentially biased by the trophic preferences of tsetse flies and by the capture method that excluded canopy levels. Previous studies have shown that hematophagous flies sampled in canopies mainly feed on arboreal species (Mavoungou et al, 2008). Therefore, changes in trap position could broaden the range of host species analysed.…”

“…Hematophagous flies (tsetse flies, stomoxids and tabanids) could be good candidates for this purpose since they are usually large Diptera (length comprised between 3 and 25 mm) and hematophagous in both sexes, with the exception of male tabanids (Mullens, 2002). They are easy to trap and some studies performed on tsetse flies and stomoxids showed that 20 to 40% of trapped flies are engorged with blood (Mavoungou et al, 2008;Simo et al, 2012). These flies feed on a large spectrum of vertebrate hosts, including birds, reptiles and mammals (Muturi et al, 2011;Clausen et al, 1998;Muzari et al, 2010).…”

Spatio‐temporal variation of biting flies, Stomoxys spp. (Diptera: Muscidae), along a man‐made disturbance gradient, from primary forest to the city of Makokou (North‐East, Gabon)

“…Many others uncontrolled factors might also explain variations in species abundances observed, such as the vertical distribution of species in forest layers (Mavoungou et al ., 2012), and the diversity and relative abundance of feeding animal hosts (Mavoungou et al ., 2008b), as it has been shown for Glossina frezili in another rainforest area (Gouteux et al ., 1991).…”