Are bogs reservoirs for emerging disease vectors? Evaluation of Culicoides populations in the Hautes Fagnes Nature Reserve (Belgium)

Several species of Culicoides (Diptera: Ceratopogonidae) biting midges serve as biological
vec{ors for the bluetongue virus (BTV) and the recently described Schmallenberg virus in
northern Europe. since their recent emergence in this part of the continent, these diseases
have caused considerable economic losses to the sheep and cattle industries. Much data is
nou, âvailable that describe the distribuüon, population dynamics, and feeding habits of these
insects. However, little is known regarding the presence of culicoides in unusual habitats
such as peaÿ marshes, nor their potential vector capacity.
This study evaluated Culicoides biting midges present in the bogs of a Belgian nature
reserve compared to those residing at a nearby cattle farm. Culicoides were trapped in 2011
at four different sites (broadleaved and coniferous forested areas, open environments, and at
a scientific station) located in the Hautes Fagnes Nature Reserve (Belgium). An additional
light trap was operated on a nearby caftle farm. High numbers of biting midges were
captured in the marshy area and most of them were Culicoides impunc{atus, a potential
vector of BïV and other pâthogens. ln addition, fewer numbers of c. obsoletus/c. scoticus
species, C. chiopterus, and C. dewulfi were observed in the bogs compared to the farm. The
wet environment and oligotrophic nature of the soil were probably responsible for these
changes in the respective populations. A total of 297,808 Culicoides midges belonging to 27
species were identified during this study and 3 of these species (C. sphagnumensis, C.
clintoni and C. comosioculatus) were described in Belgium for the first time.