Table 1.

Ecological risk factors associated with the spread and sustained circulation of three mosquito-borne viruses (i.e. RVFV, JEV and WNV) and three tick-borne viruses (TBEV, LIV and CCHFV) that were included for the development of hazard maps for arbovirus introduction and establishment

	Introduction risk factors	Establishment risk factors
		Abiotic	Host	Vector
Mosquito-borne viruses
RVFV	na	Positive effect of TG from April to October	Abundance of ruminant livestock (i.e. sheep, goat, and cattle)	Culex and Aedes abundance
JEV	Abundance of birds with overlapping migratory flyways with conspecifics from JEV-endemic areas in Asia	Number of days with TX ≥ 25 °C	Abundance of ardeid bird species and domestic pigs	Culex abundance
WNV	Abundance of bird species that migrate from Africa and/or the Mediterranean area to the Netherlands in spring	Positive effect of TG from April to October	Abundance of wetland birds, crow, jackdaw, magpie, pigeon, and house sparrow	Culex abundance
Tick-borne viruses
TBEV	na	Slope of TG decrease from August to October Slope of TG increase from March to May Positive effect of UG from April to October	Presence of deer and free-ranging livestock (i.e. cattle, sheep, goat, horse)	Suitable habitat for I. ricinus ticks
LIV	na	Slope of TG decrease from August to October Slope of TG increase from March to May Positive effect of UG from April to October	Abundance of sheep	Suitable habitat for I. ricinus ticks
CCHFV	Abundance of bird species that migrate from Africa and/or the Mediterranean area to the Netherlands in spring	Negative effect of RH Positive effect of TG from April to October	Abundance of livestock (i.e. cattle, horse, sheep, goat)	Suitable habitat for H. marginatum ticks

Choice of the below listed factors was based upon the systematic review of Esser et al. [22]

Abbreviations: UG, 24 h average relative humidity; RH, 24 h sum of precipitation; TG, 24 h average temperature; TX, 24 h maximum temperature