Parasitellus

Common in the Holarctic region (North America, Europe, Northern Asia, and China). Also reported in the Neotropical region (Argentina and Mexico).[8]

All species of Parasitellus inhabit nests of bumble bees (Bombus). Mite deutonymphs are commonly phoretic on adult bumble bees or cuckoo bumble bees. Phoretic mites prefer queens to other castes (workers and males), since bumble bee colonies are annual and only young queens overwinter. Mites dispersing on workers and males may try to switch to queens later, either during copulation or on flowers, where bumble bees forage.[10][11]

Species of Parasitellus are not specific to a particular bumble bee species, with different mite species often co-occurring in a single Bombus nest or co-dispersing on a single bee individual.

The nature of the association between Parasitellus and its bumble bee hosts is a balance between being harmful and beneficial. In Parasitellus fucorum, males, larvae, protonymphs, and possibly deutonymphs, have been found to be predatory or oophagous (egg-feeding) on microarthropods in bumble bee nests and thus, beneficial to the bees, while adult females and deutonymphs preferentially feed on the provisioned pollen and are harmful to the host.[12]

Mites feed on the upper layer of pollen grains (nectar coating and pollenkitt), without damaging them otherwise. Pollen grains processed in this way lost their normal bright yellow or blue color and became pale and more translucent.[12]