Effectiviness and environmental hazards of acaricides applied to large mammals for tick control

Ticks are important vectors of a large number of pathogenic organisms. In the Netherlands, Ixodes ricinus is the most abundant tick species and the main vector for several Borrelia species that may cause Lyme borreliosis. Many chemicals have been developed for tick control. In this chapter, a few commonly used acaricides are discussed with the main aim to assess whether they could be both effective and environmentally safe enough for tick control in the field through application on large mammals. This method is currently still at the experimental stage and only limitedly applied. The focus was on amitraz, permethrin, flumethrin, deltamethrin and ivermectin. After a qualitative comparison of the pros and cons, it was concluded that the pyrethroids flumethrin and deltamethrin are potentially the most useful, despite their high toxicity to various other animals in the environment. Both compounds act as contact-acaricides and are not easily leached in the environment. Environmental hazards can therefore be minimised if they are applied correctly and thoughtful, and contamination of the aquatic environment is avoided. Nevertheless, all synthetic acaricides have a number of serious downsides and, when considering using them in field situations, the benefits always need to be weighed against all costs involved. More environmentally-friendly alternatives are being developed of which vaccines against ticks seem most promising.