Investigation of Ground Level and Remote-Sensed Data for Habitat Classification and Prediction of Survival of <I>Ixodes scapularis</I> in Habitats of Southeastern Canada

Abstract

In southeastern Canada, most populations of Ixodes scapularis Say, the Lyme disease vector, occur in Carolinian forests. Climate change projections suggest a northward range expansion of I. scapularis this century, but it is unclear whether more northerly habitats are suitable for I. scapularis survival. In this study, we assessed the suitability of woodlands of the Lower Great Lakes/St. Lawrence Plain region for I. scapularis by comparing tick egg survival in four different woodlands. Woodlands where I. scapularis are established, and sand dune where I. scapularis do not survive, served as positive and negative control sites, respectively. At two woodland sites, egg survival was the same as at the positive control site, but at two of the sites survival was significantly less than either the positive control site, or one of the other test sites. Egg survival in all woodland sites was significantly higher than in the sand dune site. Ground level habitat classification discriminated among woodlands in which tick survival differed. The likelihood that I. scapularis populations could persist in the different habitats, as deduced using a population model of I. scapularis, was significantly associated with variations in Landsat 7 ETM+ data (normalized difference vegetation index [NDVI] and Tasselled Cap indices). The NDVI index predicted habitat suitability at Long Point, Ontario, with high sensitivity but moderate specificity. Our study suggests that I. scapularis populations could establish in more northerly woodland types than those in which they currently exist. Suitable habitats may be detected by ground-level habitat classification, and remote-sensed data may assist this process.

The Biological Survey of Canada: A Personal History

“…The prevalence and abundance of larvae decrease in July and then usually increase again in August when the larvae of that year hatch (Lindsay et al 1999b). Larval ticks are most abundant in wooded habitats (Maupin et al 1991;Lindsay et al 1999a) and survival is predicted to occur at more northerly latitudes in the face of climatic change Ogden et al 2006a). Larvae feed for up to seven days, but most drop from their hosts on the fourth day (Troughton and Levin 2007).…”

Methodological caveats in the environmental modelling and projections of climate niche for ticks, with examples for Ixodes ricinus (Ixodidae)

“…Modelling exercises of organisms tend to develop techniques that maximize the results of the predictive abilities of the projection into space, increasing the number of variables forcibly entered into the model (i.e., Liu et al, 2005;Jiménez-Valverde and Lobo, 2007). A number of modellers, however, have argued strongly for the use of predictors that are ecologically relevant to the target species (Glass et al, 1995;Randolph, 2001;Estrada-Peña, 2002;Guerra et al, 2002;Ogden et al, 2006). In this sense, Araújo and Guisan (2006) stated that the "use of automated solutions to predictor selection .…”

Climate change and tick-borne diseases: A research field in need of long-term empirical field studies

“…Perhaps the most promising data sets for studies on climate change effects on I. scapularis come from Rhode Island in the United States and Ontario in southeastern Canada (Lindsay et al, 1995;Nicholson and Mather, 1996;Ogden et al, 2006c). The recent emergence of I. scapularis on the Canadian island of Newfoundland (Artsob et al, 2000;Ogden et al, 2006b) underscores the value of including areas perceived to currently lack this tick in long-term empirical studies.…”