> ticks regularly use mice as hosts so the mice population may affect the tick population
True, (well, shrews are preferred in fact to mice), but only when young. Adult ticks feed mainly on large mammals, specially herbivores, and die if can't find a host in a few days, therefore is easy to understand that the recruitment of new ticks, the number of tick eggs released by surviving adults, is directly linked with the role of wolves as predators.
In the other hand, to put your "population of wolves has doubled between 2014 and 2015 but ticks had not changed" claim in context, we need to note that wolf population in the Netherlands between years 1869 and 2013 was composed of zero wolves.
Then, in 4-Jul-2013 something very strange happened. A she-wolf was found dead in a roadside next Luttelgeest. The first confirmed case of a "dutch" wolf in 140 years. A study in the journal Lutra covered the issue concluding that:
1) The animal was a purebreed wolf genetically related with East Europe populations [discarding a dog-wolf mix or a sarloos dog], was unchipped, and between 1.5 and 2.5 years old.
2) She fed on beaver in either the Carpathian mountains or the Eifel which is too far for the animal to have walked (9Km/h) from by itself within the 24 hours needed to digest its last meal (Genetic analysis from the remains of the beaver and the wolf linked both animals with populations living in this areas).
3) Bullet impacts and shattered fragments where found in the chest and flank indicating that the animal was shot twice before being hit by a car.
4) No car accident involving an animal was reported to local emergency services in the previous hours to the discovery of the corpse.
5) A discrepancy between the timing of the post mortem and rigor mortis intervals indicated that this wolf was shot prior to illegal transport to the Netherlands, from a distance within 2 days.
[To fake a car accident, running over a previously killed animal is a common procedure to cover environmental crimes against protected species].
Source:
The first wolf found in the Netherlands in 150 years was the victim of a wildlife crime. Lutra. 2013. 56(2): 93-109. Gravendeel, de Groot, Kik, Beentjes, Bergman, Caniglia, Cremers, Fabbri, Groenenberg, Grone, Bruinderink, Font, Hakhof, Harms, Jansman, Janssen, Lammertsma, Laros, Linnartz, van der Marel, Mulder, van der Mije, Nieman, Nowak, Randi, Rijks, Speksnijder & Vonho
Link to the article: http://www.kora.ch/fileadmin/file_sharing/5_Bibliothek/51_KO...
... So in 2013 there was still zero dutch wolves.
Then in 9-march-2015 a single wolf was photographed in Hunze.
So, unless you can show us new data, yes, wolf population was doubled in Netherlands in the last year... but you forgot to mention that is from zero to one animal. Here have your answer to the lack of changes on tick population.