Fig. 3
Visual representation of how the mean annual climate variables and the mean seasonal climate variables were calculated over three different years. The approximate 3-year life cycle of I. ricinus is shown by adult ticks that lay eggs (left panel), the eggs that hatch into larvae (middle panel), and the larvae that become nymphs (right panel). The bimodal or unimodal distribution in each panel represents the phenology of each tick stage. The three calendar years are shown by the vertical black lines; the months are shown by the bars that are labelled below the X-axis. The four seasons of winter, spring, summer, and fall are colour-coded as blue, green, yellow, and orange, respectively. The response variable of interest is the density of nymphs (DON) in the right panel. For illustrative purposes, the explanatory variable is temperature (abbreviated as T). The three annual means of the temperature are TY2, TY1, and TY0 (labelled at the top); the subscript ‘Y’ indicates that the temperature is averaged over the calendar year; the subscripts 0, 1, and 2 indicate the time lag (i.e., 0, 1, or 2 years before the year of the DON). There are 12 seasonal means of the temperature (labelled at the bottom); the subscripts ‘W’, ‘L’, ‘S’, and ‘F’ indicate that the temperature is averaged over the winter, spring (lent), summer, and fall; the subscripts 0, 1, and 2 indicate the time lag in years. For example, TW2 is the mean temperature of the winter 2 years before the year of the DON