Modelling the Northward Expansion of Culicoides sonorensis (Diptera: Ceratopogonidae) under Future Climate Scenarios

Abstract

Climate change is affecting the distribution of pathogens and their arthropod vectors worldwide, particularly at northern latitudes. The distribution of Culicoides sonorensis (Diptera: Ceratopogonidae) plays a key role in affecting the emergence and spread of significant vector borne diseases such as Bluetongue (BT) and Epizootic Hemorrhagic Disease (EHD) at the border between USA and Canada. We used 50 presence points for C. sonorensis collected in Montana (USA) and south-central Alberta (Canada) between 2002 and 2012, together with monthly climatic and environmental predictors to develop a series of alternative maximum entropy distribution models. The best distribution model under current climatic conditions was selected through the Akaike Information Criterion, and included four predictors: Vapour Pressure Deficit of July, standard deviation of Elevation, Land Cover and mean Precipitation of May. This model was then projected into three climate change scenarios adopted by the IPCC in its 5th assessment report and defined as Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5. Climate change data for each predictor and each RCP were calculated for two time points pooling decadal data around each one of them: 2030 (2021–2040) and 2050 (2041–2060). Our projections showed that the areas predicted to be at moderate-high probability of C. sonorensis occurrence would increase from the baseline scenario to 2030 and from 2030 to 2050 for each RCP. The projection also indicated that the current northern limit of C. sonorensis distribution is expected to move northwards to above 53°N. This may indicate an increased risk of Culicoides-borne diseases occurrence over the next decades, particularly at the USA-Canada border, as a result of changes which favor C. sonorensis presence when associated to other factors (i.e. host and pathogen factors). Recent observations of EHD outbreaks in northern Montana and southern Alberta supported our projections and considerations. The results of this study can inform the development of cost effective surveillance programs, targeting areas within the predicted limits of C. sonorensis geographical occurrence under current and future climatic conditions.

Daily temperature records from a mesonet in the foothills of the Canadian Rocky Mountains, 2005–2010

“…Temperature variability across the landscape also needs to be understood to support the growing demand to model climate change impacts on Earth systems (e.g., Thomas et al, 2006;Deutsch et al, 2008;Clarke et al, 2015;Zuliani et al, 2015;Yospin et al, 2015;Franklin et al, 2016). General circulation models that are used for climate change scenarios or global climate reanalyses typically operate on scales of tens to hundreds of kilometres (e.g., Dee et al, 2011;Taylor et al, 2012;Murakami et al, 2016).…”

Key issues in the welfare of dairy cattle

“…New threats emerge from vectors spreading to previously unaffected regions due to climatic changes, such as biting midges (Culicoides spp.) that propagate the bluetongue and Schmallenberg viruses (Beer et al, 2013;Zuliani et al, 2015).…”

Evolutionary ecology of virus emergence

“…Environmental variables of elevation, temperature, and rainfall had the biggest impact on BTV spread because they affected vector abundance and host availability . Temperature, in particular, affected the magnitude of BTV's basic reproductive number ( R 0 ), a measure of the transmission potential of a disease .…”