Both females and males of the Japanese large carpenter bee Xylocopa appendiculata circumvolans Smith had a pair of mesosomal acarinaria behind the wing bases as well as the metasomal one in the first tergum. The opening to the mesosomal acarinarium was larger in male bees than in females. The metasomal acarinarium was a narrow and shallow groove rather than the invaginated chamber reported in X. flavorufa or X. latipes. Three species of mite deutonymphs were collected from X. a. circumvolans: Sennertia japonica, S. alfkeni, and Horstia helenae, of which the first two species greatly outnumbered the last. All three species were supposed to be scavengers feeding on various kinds of debris in nests of the host and cleptoparasites eating stored pollen. Sennertia japonica, which was smaller than S. alfkeni, mainly occurred in the acarinaria and wing bases, while S. alfkeni mainly in dorsolateral hair, probably because S. alfkeni was too large to enter the acarinaria. We discussed the significance of acarinarium in the genus Xylocopa from the viewpoint of mite-bee interactions.

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Neral [3,7-dimethyl-(Z)-2,6-octadienal] was identified to be the female sex pheromone of the mite Histiogaster sp. (Acari: Acaridae). The species originated from a fungal Trichoderma harzianum culture in Japan. The compound aroused males to mount females. Although the compound was detected in both sexes (29.4±8.9 ng in females and 5.7±1.9 ng in males), the behavior observation suggested that males could distinguish females from males. Synthetic neral indicated the activity at 0.1-1 ng doses. On the other hand, geranial [3,7-dimethyl-(E)-2,6-octadienal, the geometrical isomer of neral at the 2-C position], did not sexually stimulate males. Males could, therefore, discriminate between neral and geranial. Escaping behavior was observed upon exposure of neral at 100 ng and of geranial at 10-100 ng doses.

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