Pneumolaelaps

Dorsal view of female Pneumolaelaps, from Bee Mite ID.

Belongs within: Laelapidae.

Pneumolaelaps is a genus of laelapid mites found in the nests of bumblebees (Evans & Till 1979).

Breath of the hunter

The mites of the family Laelapidae are an ecologically diverse bunch. The earliest members of the family were probably free-living micro-predators, a lifestyle many maintain to this day, but many laelapids have developed close associations with other animals. Some are nest-dwelling commensals, others full blood-sucking parasites. Among those laelapids living communally are the species of the genus Pneumolaelaps.

Dorsum (left) and venter of Pneumolaelaps niutirani, from Fan et al. (2016). The peritreme is visible in ventral view as the thick line around the front and side.

Pneumolaelaps species were first described living in the nests of bumblebees Bombus spp. Since then, they have been found in association with other social Hymenoptera—honeybees Apis mellifera and German wasps Vespula germanica—as well as with the solitary bee Megachile torrida (Fan et al. 2016). They are distinguished from other laelapids by increased numbers of setae on the sides and rear of the body. The peritremes, grooves on the underside of the body near the legs that act as respiratory structures, also tend to be relatively broad (Evans & Till 1979). Presumably this last feature is where the “pneumo-“ part of their name comes from.

Pneumolaelaps individuals move rapidly about in bumblebee nests, exploring food stores and brood cells. They seem to pay particular attention to host larvae. However, it is probably not the larvae themselves that are the mites’ main target but the pollen and sugars adhering to the larva’s cuticle (Royce & Krantz 1989). Nevertheless, the mites do not appear to be above occasionally feeding on host haemolymph, particularly when bees are injured. The species P. niutirani has been suggested as a possible vector of pathogenic viruses in wasps (Felden et al. 2020). It is also possible that Pneumolaelaps predate on other scavenging mites in the nest (Costa 1966).

Pneumolaelaps hitching a lift on a German wasp, from Geoff Ridley.

Eggs of Pneumolaelaps are laid within the host nest and are among the largest relative to adult body size of any mesostigmatan mite. Costa (1966) suggested that P. hyatti was both oviparous (egg-laying) and larviparous (giving birth directly to active larvae), having observed both eggs and larvae in laboratory colonies within a couple of hours of their introduction. Alternatively, it is possible that the eggs are laid at an advanced stage of development and hatch rapidly. As the nest reaches the end of its life, the mites cling onto the mature wasps and bees. In this position, they pass the winter attached to the host, waiting for new nests next year.

Systematics of Pneumolaelaps

Characters (from Evans & Till 1979): Apotele with two tines; opisthogastric and lateral unsclerotized cuticle hypertrichous; peritreme often broad; genu IV with two ventral setae; female with anal shield free, metasternal setae not situated on sternal shield.

<==Pneumolaelaps Berlese 1920FH93
    |--*P. bombicolens (Canestrini 1885)ET79 [=Iphis bombicolensFH93, Hypoaspis (*Pneumolaelaps) bombicolensS61]
    |--P. aequalipilus Hunter 1966FH93
    |--P. arctos (Karg 1984) [=Hypoaspis (Pneumolaelaps) arctos]FH93
    |--P. connieae Hunter & Husband 1973FH93
    |--P. costai Hunter & Husband 1973FH93
    |--P. groenlandicus (Trägårdh 1906) [=Hypoaspis bombicolens var. groenlandica]FH93
    |--P. hyatti (Evans & Till 1966) [=Hypoaspis hyatti]FH93
    |--P. karawaiewi (Berlese 1904) [=Laelaps (Androlaelaps) karawaiewi]FH93
    |--P. longanalis Hunter & Husband 1973FH93
    |--P. longipilus Hunter 1966FH93
    |--P. lubricus (Voigts & Oudemans 1904) (see below for synonymy)FH93
    |--P. mistipilus Hunter 1966FH93
    |--P. patae Hunter & Husband 1973FH93
    |--P. richardsi Hunter & Husband 1973FH93
    |--P. shealsi (Hunter & Costa 1971) [=Gymnolaelaps shealsi]FH93
    `--P. sinhai Hunter & Husband 1973FH93

Pneumolaelaps lubricus (Voigts & Oudemans 1904) [=Hypoaspis lubrica; incl. H. compressus Hull 1925, H. (Haemolaelaps) inversus Berlese 1918 non Parasitus inversus Banks 1916, H. murinus Strandtmann & Menzies 1948, H. smithii Hughes 1948]FH93

*Type species of generic name indicated

References

Costa, M. 1966. The biology and development of Hypoaspis (Pneumolaelaps) hyatti (Acari: Mesostigmata). Journal of Zoology 148: 191–200.

[ET79] Evans, G. O., & W. M. Till. 1979. Mesostigmatic mites of Britain and Ireland (Chelicerata: Acari-Parasitiformes). An introduction to their external morphology and classification. Transactions of the Zoological Society of London 35: 139–270.

Fan, Q.-H., Z.-Q. Zhang, R. Brown, S. France & S. Bennett. 2016. New Zealand Pneumolaelaps Berlese (Acari: Laelapidae): description of a new species, key to species and notes on biology. Systematic and Applied Acarology 21 (1): 119–138.

[FH93] Farrier, M. H., & M. K. Hennessey. 1993. Soil-inhabiting and free-living Mesostigmata (Acari-Parasitiformes) from North America: an annotated checklist with bibliography and index. North Carolina Agricultural Research Service, North Carolina State University, Technical Bulletin 302: i–xvi, 1–408.

Felden, A., J. W. Baty, M. Bulgarella, R. L. Brown, J. Dobelmann, M. A. M. Gruber, O. Quinn & P. J. Lester. 2020. Viral and fungal pathogens associated with Pneumolaelaps niutirani (Acari: Laelapidae): a mite found in diseased nests of Vespula wasps. Insectes Sociaux 67: 83–93.

Royce, L. A., & G. W. Krantz. 1989. Observations on pollen processing by Pneumolaelaps longanalis (Acari: Laelapidae), a mite associate of bumblebees. Experimental and Applied Acarology 7: 161–165.

[S61] Schweizer, J. 1961. Die Landmilben der Schweiz (Mittelland, Jura und Alpen): Parasitiformes Reuter, mit 246 Arten und Varietäten und 268 meist kombinierten Originalzeichnungen. Denkschriften der Schweizerischen Naturforschenden Gesellschaft [Mémoires de la Société Helvétique des Sciences Naturelles] 84: i–vii, 1–207.

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