Parasitellus

Harmfulness rating

HARMFUL | NOT HARMFUL | UNCERTAIN

kleptoparasitic or neutral to beneficial, depending on life stage; females and deutonymphsdeutonymph:
Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
feed on provisioned pollen, while other stages are predators of small arthropods

Name

Parasitellus Willmann, 1939

Taxonomy

Superorder Parasitiformes » Order Mesostigmata » Suborder Monogynaspida » Hyporder Parasitiae » Family Parasitidae » Genus Parasitellus

Type species

Eugamasus (?) ferox Tragardh, 1910 (= Acarus fucorum De Geer, 1778)

Common synonyms

In old literature has been treated as part of Parasitus Latreille, 1795.

Diagnosis

Adult and deutonymphdeutonymph:
Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
: In both adults and deutonymphsdeutonymph:
Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
, opisthogastric regionopisthogastric region:
Ventral body behind legs IV. Also known as opisthogaster and ventral opisthosoma.
has more than 40 pairs of setae (Fig. 2). In all other species of Parasitidae, opisthogastric regionopisthogastric region:
Ventral body behind legs IV. Also known as opisthogaster and ventral opisthosoma.
has fewer than 30 pairs of setae.

Species identification

A key to species from North America is available from the bee-associated mites website. A key to species from the British Isles is available in Hyatt, 1980Hyatt, 1980:
Hyatt, K. H. 1980. Mites of the subfamily Parasitinae (Mesostigmata: Parasitidae) in the British Isles. Bulletin of the British Museum (Natural History) Zoology. 38: 237-378..

Similar genera

Parasitellus can be distinguished from all other genera of Parasitidae by the opisthogastric regionopisthogastric region:
Ventral body behind legs IV. Also known as opisthogaster and ventral opisthosoma.
having more than 40 pairs of setae (Fig. 2). This region has fewer than 30 pairs of setae in other genera of Parasitidae.

Distribution

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

Bee hosts

All species of the genus Parasitellus are obligatory associates of bumble bees (Bombus). Several occasional records are from honey bee (Apis) hives and burrows of small mammals (which are preferential sites for bumble bee nests).

Host association level

permanentpermanent:
associated exclusively with bees or their close relative, wasps; cannot live without these hosts

Host associations, feeding, and dispersal

• All stages live in nests of bumble bees (Bombus spp.), where females and deutonymphsdeutonymph:
  Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
  feed on pollen and other stages feed on small arthropods.
• Mite deutonymphsdeutonymph:
  Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
  disperse and overwinter on adult queen bees. Phoresyphoresy:
  Attaching to or boarding another organism (i.e., a host) for dispersal to new habitats. Can be distinguished from parasitism because feeding typically does not occur.
  on workers and males of bumble bees or cuckoo bumble bees is also documented.

Biology

All species of Parasitellus inhabit nests of bumble bees (Bombus). Mite deutonymphsdeutonymph:
Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
are commonly phoreticphoretic:
Pertaining to phoresy; using another organism (i.e., a host) for dispersal to new habitats. Phoresy can be distinguished from parasitism because feeding typically does not occur during phoresy.
on adult bumble bees or cuckoo bumble bees. Phoreticphoretic:
Pertaining to phoresy; using another organism (i.e., a host) for dispersal to new habitats. Phoresy can be distinguished from parasitism because feeding typically does not occur during phoresy.
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 (Huck et al., 1998Huck et al., 1998:
Huck, K., H. H. Schwarz amp; P. Schmid-Hempel. 1998. Host choice in the phoretic mite Parasitellus fucorum (Mesostigmata: Parasitidae): which bumblebee caste is the best? Oecologia.115: 385-390.; Schwarz and Huck, 1997Schwarz and Huck, 1997:
Schwarz, H. H. amp; K. Huck. 1997. Phoretic mites use flowers to transfer between foraging bumblebees. Insectes Sociaux. 44: 303-310.).

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, protonymphsprotonymph:
Ontogenetic stage between larva and deutonymph. See Life stages page for more details.
, and possibly deutonymphsdeutonymph:
Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
, 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 deutonymphsdeutonymph:
Ontogenetic stage between protonymph and tritonymph (or adult, if tritonymph is absent).  See Life stages page for more details.
preferentially feed on the provisioned pollen and are harmful to the host (Koulianos and Schwarz, 1999Koulianos and Schwarz, 1999:
Koulianos, S. amp; H. H. Schwarz. 1999. Reproduction, development and diet of Parasitellus fucorum (Mesostigmata : Parasitidae), a mite associated with bumblebees (Hymenoptera: Apidae). Journal of Zoology.248: 267-269.).

Mites feed on the upper layer of pollen grains (nectar coating and pollenkittpollenkitt:
A sticky covering found on the surface of pollen grains.
), without damaging them otherwise. Pollen grains processed in this way lost their normal bright yellow or blue color and became pale and more translucent (Koulianos and Schwarz, 1999Koulianos and Schwarz, 1999:
Koulianos, S. amp; H. H. Schwarz. 1999. Reproduction, development and diet of Parasitellus fucorum (Mesostigmata : Parasitidae), a mite associated with bumblebees (Hymenoptera: Apidae). Journal of Zoology.248: 267-269.).