probably mutualistic because bee hosts developed acarinaria to transfer mites, though evidence somewhat contradictory
Dinogamasus Kramer, 1898
Taxonomy
Superorder Parasitiformes » Order Mesostigmata » Suborder Monogynaspida » Hyporder Dermanyssiae » Family Laelapidae » Genus Dinogamasus
Type species
Dinogamasus crassipes Kramer, 1898
Common synonyms
Greenia Oudemans, 1901; Greeniella Banks, 1904; Dolaea Oudemans, 1912
Adult: Sternal seta st3 situated off sternal shield (Figs. 2, 3). Sternal and epigynal shields distinctly separated (Figs. 2, 3). Peritremes reduced or absent, not elongated (Figs. 4, 5). Dorsum hypertrichous, especially at body margins (Fig. 1).
A dichotomous key is available in Lundqvist, 1998.
Old World tropics
large carpenter bees (Xylocopa)
associated exclusively with bees or their close relative, wasps; cannot live without these hosts
some life stages are associated with bees, while others are not
can complete entire life cycle without bees or their close relative, wasps
permanent
The biology of Dinogamasus in the bee nest is not entirely understood. Based on observations of Dinogamasus braunsi and D. villosior (Skaife, 1952; Madel, 1975), the mites apparently feed on exudates produced by the developing bee larvae and pupae, or on fungi and other microorganisms associated with them. Mites could not survive on pollen in laboratory conditions, and they cannot pierce the soft cuticule of bee larvae with their chelicerae.
After eclosion, the adult bee breaks the cell partition and spends its first days in the nest. During this time, adult females of Dinogamasus enter the metasomal acarinarium of adult female bees. The metasomal acarinaria probably serve for protected dispersal for newly emerged adult females during the period of bee dispersal from the parent nest. On average, Xylocopa flavorufa carries 21 mites of D. villosior (maximum 35) in the metasomal acarinarium, and X. caffra carries 10-12 (maximum 18). Since only female bees build nests, dispersal on males will result in mites dying without establishing colonies in new nests.
Experimental evidence is contradictory. It has been found that mites do not harm the pupa, but bees do not benefit from the mite presence either (Skaife, 1952). Alternatively, it has been demonstrated that bee pupae lose weight proportionally to the number of mites (Watmough, 1974), indicating that these mites can be harmful to their hosts. On the other hand, the presence of acarinaria is indicative of mutualistic associations. Given the contradictory evidence, more research is needed to elucidate the nature of mite-bee interactions in this system.