Using a rule-based envelope model to predict the expansion of habitat suitability within New Zealand for the tick Haemaphysalis longicornis, with future projections based on two climate change scenarios

Preliminary prediction of the potential distribution and consequences of Haemaphysalis longicornis using a simple rule-based climate envelope model

“…Third, in 20 of the 31 counties where Haemaphysalis longicornis was detected the tick was found only on animals or people (see Table 2). The simple rule-based climate envelope model by Lawrence et al (2017) was based on rules developed by Neilson (1980) using information on the off-host survival of Haemaphysalis longicornis in the lab (Heath 194, Heath 1979). Therefore, they are not necessarily representative of conditions suitable for this tick when on host.…”

“…I elected not to adopt two of the rules used by Lawrence et al (2017), and only applied 5 of his 7 environmental requirement in my analysis. The two rules I decided not to apply was that (1) frosts <50 per annum; and (2) Snow <=1 day per annum.…”

“…There are several reasons for my choice of not using these environmental criteria. First, the second criteria was not used in the end by Lawrence et al (2017) either, for lack of applicable data. I also did not have a readily available source of data for these environmental variables, as they are not part of the WorldClim or BioClim datasets (Fick and Hijmans, 2017).…”

“…The rules used in this model were derived by Neilson et al (1980) as environmental requirements based on a postal survey of sheep farmers in the Hawke's Bay and Gisborne regions of New Zealand, correlated with local climate station data, and supported by laboratory work completed by Heath on the off-host survival of H. longicornis across different conditions (Heath 1974(Heath , 1977. Lawrence et al (2017) validated this rule-based climate envelope model against a maximum entropy environmental niche model of environmental suitability for T. orientalis transmission and against a H. longicornis occurrence map in New Zealand.…”

“…Finally, I do not have access to fine enough scale information on the exact locations where the tick has been detected. Therefore, here I use a simplistic rule-based climate envelope model, basically adapting the work of Lawrence et al (2017) done in New Zealand to predict the likely distribution of the Asian longhorned (bush) tick across the United States. I use publicly available climate normal data at 2.5 minute spatial resolution (Fick and Hijmans, 2017), and provide a composite habitat suitability score for Haemaphysalis longicornis as a surface across North America, as well as a table to summarize the average suitability of each state in the United States.…”