Range expansion of the Bluetongue vector, Culicoides imicola, in continental France likely due to rare wind-transport events

Abstract

The role of the northward expansion of Culicoides imicola Kieffer in recent and unprecedented outbreaks of Culicoides-borne arboviruses in southern Europe has been a significant point of contention. We combined entomological surveys, movement simulations of air-borne particles, and population genetics to reconstruct the chain of events that led to a newly colonized French area nestled at the northern foot of the Pyrenees. Simulating the movement of air-borne particles evidenced frequent wind-transport events allowing, within at most 36 hours, the immigration of midges from north-eastern Spain and Balearic Islands, and, as rare events, their immigration from Corsica. Completing the puzzle, population genetic analyses discriminated Corsica as the origin of the new population and identified two successive colonization events within west-Mediterranean basin. Our findings are of considerable importance when trying to understand the invasion of new territories by expanding species.

Quantification of within‐ and between‐farm dispersal of Culicoides biting midges using an immunomarking technique

“…There is, however, evidence of population‐scale differences in phylogeny in Culicoides (Jacquet et al . ) that suggests the presence of barriers to the dispersal of Culicoides at a greater scale than represented in this study.…”

The impact of temperature changes on vector-borne disease transmission: Culicoides midges and bluetongue virus

“…Climate change is expected to increase the range of the important BTV transmitting midge species in Europe, such as C. imicola [56], and there is evidence that this is already occurring [57]. Climate change is likely to change the range of other potential vector species; equally climate will also affect the profitability of different farming practices, potentially leading to changes in host abundance.…”

“…Another example is the world-wide trade of animals, which can introduce novel diseases to livestock herds across vast distances (see Fèvre et al [59] for a review of a number of examples); therefore, increased international trade could increase the number of importations of infectious animals and/or midges. However, both of these are difficult to quantify (see Jacquet et al [57] for a discussion of the difficulties of quantifying midge introduction via globalized transport), and may be influenced by many factors in addition to climate change. Moreover, it is possible that VBDs are introduced into naive regions in Europe more frequently than generally supposed, albeit cryptically, but outbreaks are not observed due to introductions not coinciding with optimal climate conditions, as is suspected for Rift Valley fever virus [60].…”

First molecular identification of the vertebrate hosts of Culicoides imicola in Europe and a review of its blood‐feeding patterns worldwide: implications for the transmission of bluetongue disease and African horse sickness

“…Thus, the present results provide support for the feasibility of the COI marker as a barcoding region for use in the identification of C. imicola (Harrup et al ., ). Along with other genetic markers, study of the genetic diversity of the COI region of C. imicola has been used to examine the current distribution and colonization routes of this species in Europe (Jacquet et al ., , ). On the basis of sequences from 225 specimens collected in Europe and Africa, Jacquet et al .…”

“…Since 1998, C. imicola (along with Culicoides obsoletus and Culicoides pulicaris ) has been associated with BT outbreaks in Europe in Cyprus, Greece, Italy, Portugal, Turkey and Spain (Saegerman et al ., ). Moreover, long‐distance wind dispersal of infected Culicoides has been reported as an important factor in the range expansion of BT virus (Ducheyne et al ., ; de Diego et al ., 2012; Jacquet et al ., ).…”