Questing tick densities
All the ticks collected were identified as Ixodes ricinusspecies. Overall, questing I. ricinus nymphs and adults were
found on vegetation in all the sampled months with a unimodal pattern
(Figure 2). The main period of activity for both nymphs and adults
occurred between April/May and early July. Questing larvae were found
from April to October and in higher numbers from May to early July,
suggesting a synchronous activity with nymphs.
Questing nymph densities varied significantly between years
(Mann-Whitney U test, p-value<0.001). The annual
cumulative DON was higher in 2011 and 2013 (respectively 500 and 575
nymphs/100 m² with a maximum density per month of 270 and 350 nymphs/100
m²) than in 2012 and 2014 (respectively 120 and 240 nymphs/100 m² with a
maximum density per month of 110 and 150 nymphs/100 m²) (Figures 2 and
3). The annual cumulative density of questing adults fluctuated in line
with the annual cumulative DON, although the annual variations were
lower than for the nymphs. It varied from 12-18 adults/100 m² in 2012
and 2014 to 25-28 adults/100 m² in 2011 and 2013.