Acarinarium

An acarinarium is a specialized anatomical structure which is evolved to facilitate the retention of mites on the body of an organism, typically a bee or a wasp. The term was introduced by Walter Karl Johann Roepke.

The acarinarium has evolved to enhance the mutualistic relationship between the mites and the host organism. There are numerous cases where mites are phoretic on organisms that benefit from the mites' presence; cases where the host's body has changed over evolutionary time to accommodate the mites are far less common. The best-known examples are among the Apocritan Hymenoptera, in which the hosts are typically nest-making species, and it appears that the mites feed on fungi in the host nests (thus keeping away the fungi from host's offspring or their provisions), or possibly other parasites or mites whose presence in the nest is detrimental to the hosts. It is especially telling that nearly all the examples involve only the females of the host species, as it is the females that build and provision the nests. Fossil evidence of halictid bees with an acarinarium is found in the extinct genus Oligochlora from Dominican amber deposits on Hispaniola.

The presence or absence of this structure has been used as a taxonomic character.

Several examples can be found among the bees, and in most such cases, only the females possess acarinaria:

Other examples include:

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