This mite is passed on at birth and is carried by almost everyone, with its numbers peaking in adults as pores enlarge. They are about 0.3 mm long, are found in hair follicles on the face and nipples, including eyelashes, and eat sebum naturally released by cells in the pores. They become active at night and move between follicles in search of mating.
The first-ever genome-sequencing study of D. folliculorum mites finds that their isolated existence and resulting inbreeding are causing them to shed unnecessary genes and cells and transition towards transitioning from external parasites to internal symbionts .
Dr Alejandra Perotti, Associate Professor of Invertebrate Biology at the University of Reading, who co-led the study, said they found that the mites had body parts that were genetically arranged differently from other similar species because they had adapted to live covertly in the pores. These changes in their DNA lead to some unusual physical features and behaviors.
Due to their isolation, no exposure to external threats, no competition to infest their hosts, and no encounters with other mites with different genes, the reduction in genes makes them extremely simple organisms with only 3 single-celled muscles powered by calf. They survive with the fewest protein species, the lowest numbers seen in this and related species.
A reduction in this gene is also responsible for their nocturnal behavior. These mites lack UV protection and have lost the genes that make animals wake up to sunlight. They were also unable to produce melatonin, a compound that makes small invertebrates active at night. However, they are able to use the melatonin hormone secreted by human skin at dusk to fuel their overnight mating activities.
