Getting mites and ticks under control

Mites and ticks are agricultural, domestic animal and human pests responsible for major economic losses every year. These pests can be controlled with high efficacy using pyrethroid insecticides, but resistance to these chemicals has been evolving in mite and tick populations in the last decades.

The 'Mode of action and selectivity of pyrethroids on economically important mites and ticks' (PYNAMITE) project set out to better understand the pyrethroids mechanism of action. At the same time, the project looked for pyrethroid resistance in several pest species, and investigated why resistance differs between species.

Researchers began by studying the structure of voltage-gated sodium channels (VGSCs), a protein targeted by pyrethroid insecticides on the membrane of insect cells. They found many differences in the areas directly in contact with pyrethroids, giving a reason for the wide variation in susceptibility among species.

Another aspect of PYNAMITE used molecular techniques to analyse the genetic sequences associated with VGSCs in a wide range of mites and ticks. This work also identified species-specific differences that could be used to design targeted insecticides.

Finally, PYNAMITE collected Varroa destructor mites (partly responsible for the worldwide decline in bee health) from bee colonies around Europe, and searched for pyrethroid resistance. Researchers narrowed down the resistance to a specific mutation in the VGSC gene. From this work, scientists designed a rapid assay that can detect pyrethroid resistance in V. destructor populations.

Research into pyrethroid resistance in mites and ticks has produced new knowledge and tools that can help in controlling these damaging pests. With time, these results will translate into more effective pest control around the world.