Insecticides were introduced in the 20th century as an alternative way ofĀ treating head lice. Data from over-the-counter pesticide solutions in the 1980s showed high efficacy in killing head lice.
ButĀ liceĀ are quick to adapt to changes in their environment. Thatās why lice are studied by evolutionary parasitologists. The parasitologists can observe the lice evolving over multiple generations in just a few months.
Head lice are no exception. Around the turn of the 21st century, there began to be reports that head lice were developing resistance toĀ lice shampoosĀ and similar products containing pesticides.
Since then, many studies have further documented that these āsuper liceā have evolved resistance to certain pesticides, and that many pesticide-based lice products are no longer achieving the high efficacy rates they once did.
Lice resistance should not be an issue for lice treatments usingĀ lice combsĀ or dehydration (desiccation). It is highly improbable that lice will be able to evolve resistance to theĀ AirAllĆ©Ā®Ā device (which kills head lice through dehydration) because the mutations involved in resistance to pesticides would not protect lice from desiccation. Evolving āresistanceā to desiccation would be akin to evolving the ability to go without water.