Forcellinia

 

HARMFUL | NOT HARMFUL | UNCERTAIN

probably commensal or somewhat beneficial; feeds on fungi and decomposing organic matter in nest

Name and classification

Forcellinia Oudemans, 1924

Taxonomy
Superorder Acariformes » Order Sarcoptiformes » Suborder Oribatida » Infraorder Desmonomata » Hyporder Astigmata » Family Acaridae » Genus Forcellinia

Type species
Tyroglyphus wasmanni Moniez, 1892

Common synonyms
Dorylacarus Mahunka, 1979 and Ocellacarus Mahunka, 1979; probably Hungaroglyphus Mahunka, 1962 and Paraforcellinia Kadzhaja, 1973

Diagnosis

Phoretic deutonymph: Conoidal setae 4a bilobed (Fig. 3), but see the "Similar genera" topic below.

Other diagnostic characters

Phoretic deutonymph: Tarsal setae aa I present, very long. Tarsal seta ba I absent, setae ba II present. Solenidia ω1 and ω3 closely associated on tarsus I. Solenidion ω2 present. External conoidal setae ps2 of attachment organ clearly anterior to median sucker (ad1+2) (Fig. 3). Sternal apodeme and anterior apodemes II extending to level of coxal apodemes III (Fig. 3). Setae of coxal fields 1a, 3a, and 4a conoidal (Fig. 3). Empodial claws of pretarsi I-IV similar in form. Setae gT I-II and hT I-II smooth. Genua III-IV subequal to tibiae III-IV. Genu III without a short dorsal solenidion (σ).

Adult: Genu I with solenidion σ' no more than three times longer than σ'' (Fig. 6). Setae ve barbed, subequal to vi (Forcellinia and Hungaroglyphus) (Fig. 6) or 40-50% of the length of vi (Paraforcellinia). Setae ve situated near anterior lateral corners of prodorsal sclerite, so setae ve and vi are both situated on the same transverse level (Fig. 6). Setae si subequal with se or shorter (Fig. 6). Dorsal setae flattened and pectinate (Fig. 6). At least some anterior hysterosomal setae rounded at tips (Fig. 6).

Species identification

A dichotomous key to phoretic deutonymphs, available in Fain, 1987, can be used to identify Forcellinia galleriella recorded from ants and beehives. Later this species was split into Forcellinia galleriella (in strict sense) and Forcellinia faini, also found in bee hives. Delfinado-Baker and Baker, 1989 can be used to distinguish these two species.

Similar genera

Phoretic deutonymphs of Tyrophagus and Forcellinia are morphologically indistinguishable. Adults of Tyrophagus have internal scapular setae (si) distinctly longer than se (si and se subequal or si shorter in adults of Forcellinia).

Distribution

Cosmopolitan; records from bees are from the Nearctic, Palaearctic, Oriental, and Australian regions.

Bee hosts

Some species develop large population sizes in nests of honey bees (Apis) and stingless bees (Meliponini).

Host association level

Permanent

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

Temporary

some life stages are associated with bees, while others are not

Facultative or opportunistic

can complete entire life cycle without bees or their close relative, wasps

facultative (Forcellinia galleriella) or probably permanent (Forcellinia faini)

Host associations, feeding, and dispersal

  • All stages live primarily in ant nests but occasionally expand to different habitats, e.g., beehives (Forcellinia galleriella). One species, Forcellinia faini, routinely occurs in debris of beehives of Apis in the tropics and may be a bee specialist; in bee nests, it presumably feeds on decomposing organic matter and associated fungi.
  • Phoretic deutonymphs have been found on ants but not on bees.

Biology

Species of Forcellinia are primarily associated with ants (Formicidae), living in their nests as feeding stages and dispersing on adult ants as phoretic deutonymphs. For example, F. wasmanni feeds on dead ants and organic detritus in the lower level of ants' nests. Some species develop large population sizes in nests of honey bees (Apis) and stingless bees (Meliponini). They may occasionally occur in house dust (Forcellinia galleriella) (Andrews et al., 1995) and stored products such as dried milk (Forcellinia breviseta), in forest litter or under bark (Forcellinia diamesa), and in sweepings from grain stores and rotting potatoes. Feeding habits are unknown, but they presumably feed on decomposing organic matter and fungi. It is unlikely, although not entirely impossible, that Forcellinia species may attack pollen. Most bees store pollen in sealed cells, and it appears that Forcellinia lacks adaptations to either penetrate the sealed cells or sneak into them before they are sealed.

Two described and one undescribed species are known from nests of honey bees: Forcellinia galleriella (Apis mellifera), Forcellinia faini (Apis mellifera and Apis cerana), Forcellinia sp. (beehives in Hong Kong) (Bowman and Ferguson, 1985; Delfinado-Baker and Baker, 1989). Forcellinia galleriella probably opportunistically invaded beehives from an ant nest. The second species (F. faini) is probably more specific to bees (there are several repetitive records from different countries), although its potential associations with ants cannot be ruled out. In Thailand, these mites were very common in beehive debris of Apis cerana but were never found in close associations with the bees (Fain and Gerson, 1990).

In Costa Rica and Brazil, we observed that Forcellinia was common in two nests of stingless bees, probably feeding on fungi growing in abundance in old nest material. In both cases, an active ant nest was present inside or immediately nearby the bee nest, suggesting that occurrence of Forcellinia in nests of meliponine stingless bees is attributable to mites' spill-over from ant nests rather than to their long-term associations with bees. We hypothesize that since phoretic deutonymphs of Forcellinia have never been found on adult bees to date, it is likely that dispersal of these mites to beehives can be accomplished by ants entering bee nests in search for food but not by bees themselves.