Ecological Niche Modeling the Potential Geographic Distribution of 2 Four Culicoides Species of Veterinary Significance in Florida 3 4 Kristin E
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bioRxiv preprint doi: https://doi.org/10.1101/447003; this version posted October 18, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Ecological niche modeling the potential geographic distribution of 2 four Culicoides species of veterinary significance in Florida 3 4 Kristin E. Sloyer1*, Nathan D. Burkett-Cadena1, Anni Yang2, Joseph L. Corn3, Stacey L. 5 Vigil3, Bethany L. McGregor1, Samantha M. Wisely4, and Jason K. Blackburn2,5 6 7 1 Florida Medical Entomology Laboratory, University of Florida, Vero Beach, FL, USA 8 2 Spatial Epidemiology and Ecology Research Laboratory, Geography Department, University of 9 Florida, Gainesville, FL, USA 10 11 3 Southeastern Cooperative Wildlife Disease Study, University of Georgia, Athens, GA, USA 12 4 Department of Wildlife, Ecology and Conservation, University of Florida, Gainesville, FL, USA 13 5 Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA 14 15 Author Emails: 16 Kristin Sloyer (corresponding): [email protected] 17 Nathan Burkett-Cadena: [email protected] 18 Anni Yang: [email protected] 19 Joseph Corn: [email protected] 20 Stacey Vigil: [email protected] 21 Bethany McGregor: [email protected] 22 Samantha Wisely: [email protected] 23 Jason K. Blackburn: [email protected] 1 bioRxiv preprint doi: https://doi.org/10.1101/447003; this version posted October 18, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 24 Abstract 25 Epizootic hemorrhagic disease (EHD) is a viral arthropod-borne disease affecting wild 26 and domestic ruminants. EHD virus (EHDV) is transmitted to vertebrate animal hosts by biting 27 midges in the genus Culicoides. Culicoides sonorensis Latreille is the only confirmed vector of 28 EHDV in the United States but is considered rare in Florida and not sufficiently abundant to 29 support EHDV transmission. This study used ecological niche modeling to map the potential 30 geographical distributions and associated ecological variable space of four Culicoides species 31 suspected of transmitting EHDV in Florida, including Culicoides insignis, Culicoides stellifer, 32 Culicoides debilipalpis and Culicoides venustus. Models were developed with the Genetic 33 Algorithm for Rule Set Production in DesktopGARP v1.1.3 using species occurrence data from 34 field sampling along with environmental variables from WorldClim and Trypanosomiasis and 35 Land use in Africa. For three Culicoides species (C. insignis, C. stellifer and C. debilipalpis) 96- 36 98% of the presence points were predicted across the Florida landscape (63.77% - 72.53%). 37 For C. venustus, models predicted 98.00% of presence points across 27.42% of Florida. 38 Geographic variations were detected between species. Culicoides insignis was predicted to be 39 restricted to peninsular Florida, and in contrast, C. venustus was predicted to be primarily in 40 north Florida and the panhandle region. Culicoides stellifer and C. debilipalpis were predicted 41 nearly statewide. Environmental conditions also differed by species, with some species’ ranges 42 predicted by more narrow ranges of variables than others. The Normalized Difference 43 Vegetation Index (NDVI) was a major predictor of C. venustus and C. insignis presence. For C. 44 stellifer, Land Surface Temperature, Middle Infrared were the most limiting predictors of 45 presence. The limiting variables for C. debilipalpis were NDVI Bi-Annual Amplitude and NDVI 46 Annual Amplitude at 22.45% and 28.09%, respectively. The model outputs, including maps and 47 environmental variable range predictions generated from these experiments provide an 48 important first pass at predicting species of veterinary importance in Florida. Because EHDV 2 bioRxiv preprint doi: https://doi.org/10.1101/447003; this version posted October 18, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 49 cannot exist in the environment without the vector, model outputs can be used to estimate the 50 potential risk of disease for animal hosts across Florida. Results also provide distribution and 51 habitat information useful for integrated pest management practices. 52 53 Introduction 54 Vector-borne pathogens can only exist in a permissive environment that supports 55 appropriate vectors (and hosts), such that the distribution of disease is linked to vector 56 distribution. Species distribution models (SDMs) can be used to map the potential distribution of 57 disease vectors allowing inference of disease risk [1–4]. In disease ecology, SDMs are useful to 58 determine the potential current and future geographic distribution of vector species as proxies 59 for the pathogens they transmit [2,4–6]. Modeling probable occurrence is important because the 60 act of in situ surveillance requires extensive resources (e.g. personnel, sampling equipment, 61 and laboratory resources) [7]. More simply, map predictions help researchers better understand 62 where vector-borne disease risk is most likely and to target surveillance to areas of highest risk. 63 Ecological niche models (ENMs) are SDMs commonly used to predict the geographic 64 distribution of a species by determining the most likely environmental conditions associated with 65 collection locations of the target species [8]. The modeling process is rooted in ecological niche 66 theory, with a focus on the Hutchisonian n-dimensional hyper volume [9] of conditions 67 supporting a species on the landscape. A niche is a specific set of environmental conditions 68 which allows for the presence of a species. Simply put, niche theory states that no two species 69 can occupy the same ecological niche, in the case of this work, no two species will cohabitate 70 the same median ranges for all variables. Broadly, ENMs apply each unique set of ecological 71 parameters allowing for a species to maintain a population without immigration [9,10], with a 72 focus on abiotic and climatological conditions that support a species [11]. In general, ENMs use 3 bioRxiv preprint doi: https://doi.org/10.1101/447003; this version posted October 18, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 73 either presence-only or presence and absence data of a target species and environmental 74 covariates to identify non-random patterns relating species occurrence to the landscape [12]. A 75 list of commonly used models include machine learning techniques such as MAXENT [13] 76 Boosted Regression Trees [14], Random Forest [15], and the Genetic Algorithm for Rule-Set 77 Production (GARP) [1,12]. 78 Epizootic hemorrhagic disease virus (EHDV) and blue tongue virus (BTV) (Reoviridae: 79 Orbivirus) are economically important pathogens transmitted by biting midges of the genus 80 Culicoides Latreille (Diptera: Ceratopogonidae), which can cause disease in a variety of 81 ruminant species worldwide. While many vector species have been identified, vectors have yet 82 to be determined in several regions. In Europe, Asia, and Africa, confirmed BTV vectors and 83 suspected EHDV vectors are Culicoides obsoletus (Meigen), Culicoides scoticus Downes & 84 Kettle, Culicoides pulicaris (Linnaeus), Culicoides imicola Keiffer, with Culicoides dewulfi 85 Goetghebuer, and Culicoides chiopterus (Meigen) also known to transmit the viruses in Europe 86 [16]. In North America, the sole confirmed vector of EHDV is Culicoides sonorensis Latreille, 87 which along with Culicoides insignis Lutz is also a confirmed vector of BTV [17,18]. This poses 88 an issue for parts of the United States, such as Florida, where EHDV epizootics occur but C. 89 sonorensis is absent. Suspected vectors of EHDV in Florida include C. insignis, Culicoides 90 stellifer (Coquillett), Culicoides venustus Hoffman, and Culicoides debilipalpis Lutz [18–21]. 91 Several studies in Europe, Africa, and the Americas have investigated the environmental 92 factors associated with the geographic distributions of multiple Culicoides species. In Portugal, 93 generalized linear mixed models were used to demonstrate the most important environmental 94 factors predicting the distribution of European disease vectors [22]. Diurnal temperature range, 95 number of frost days, cold stress, dry stress, and median monthly temperature were the most 96 important factors driving the distribution of C. imicola [22,23], the primary BTV vector in Europe. 97 In contrast, the distributions of species within the Obsoletus group (C. chiopterus, C. dewulfi, C. 4 bioRxiv preprint doi: https://doi.org/10.1101/447003; this version posted October 18, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 98 scoticus, C. obsoletus, and Culicoides montanus Shakirzjanova) were predicted by diurnal 99 temperature range,