Persistence (a) and the distribution of extinction dates (b) as a function of host regime, and survival rate of the vector (<i>1-m_V</i>), duration of extrinsic incubation period (<i>1/q_unf</i>), and biting rate (<i>n_unf</i>) during the unfavourable period.

<p>a) solid line, most likely values 1/<i>q_unf</i> = 20 days and <i>n_unf</i> = 1/20; dashed line same values as in the favourable period 1/<i>q_unf</i> = 10, <i>n_unf = </i>1/7; dotted black line extreme values 1/<i>q_unf</i> = 100, <i>n_unf</i> = 1/100. b) 1/<i>q_unf</i> = 20, <i>n_unf = </i>1/20. In black persistence. In shades of grey, from darkest to lightest, extinction the 5th, 4th, 3rd year after introduction, respectively. In white, extinction the 2nd year. In marble, extinction the 1st year.