Bee

Mite ID

Adult: Body with dense, equal, small, rounded protuberances (Fig. 4). Tarsal setae aa I absent (Fig. 6). Proral setae of tarsi I-IV, enlarged, claw-like (Fig 6). Internal scapular setae (si) near posterior margin of prodorsal sclerite (Fig 7). Supracoxal setae filiform, barbed (Fig 7). Hysterosomal setae long, many reaching bases of next setae (Fig. 8).

Other diagnostic characters

Phoretic deutonymph: Setae ve present; setae ba I absent; ba II present (Fig. 3). Seta aa I absent (Fig. 3). Setae e I-II, short, filiform (no "saucer" at tip) (Fig. 3). Leg IV shorter than leg III (Figs. 2, 3a, and with three long apical setae (Fig. 2). Empodial claws I-III arising directly from tarsal apices (no elongated membranous ambulacra) (Fig. 2). Empodial claw IV absent (Figs. 2, 3a).

Adult: Pretarsal ambulacrum not greatly expanded (Fig. 6). Ventral subcapitulum without external ridges (Fig. 9). Dorsal setae smooth (Fig. 4). Prodorsum with external vertical setae ve present, situated at anterior level of prodorsal sclerite (Fig. 7). Anus positioned near posterior margin of body (Fig. 5). Coxal apodemes III-IV present (Fig. 5). Empodial claws simple (Fig 6). Solenidion ω2 of tarsus I more distal than ω1, situated in distal half of tarsus (Fig 6). Setae e and f present on tarsi I-IV, both filiform (Fig 6).

This genus needs a revision. There is no key to species. Original species descriptions should be consulted.

Nearctic, Palaearctic (including Japan and North Africa), Neotropical, and Australian regions. Mites found on bees are known from the Nearctic and Palaearctic.

Phoretic hosts include orchard mason bees (Osmia), leafcutting and resin bees (Megachile), bumble bees (Bombus), and large carpenter bees (Xylocopa), as well as kleptoparasitic bees of the genus Stelis (Megachilidae).

One lineage, including Tortonia dogaressa and Tortonia smitsvanburgsti, is exclusively associated with the megachilid bees of the genus Rhodanthidium.

permanent in nests

• Feeding stages live in nests of solitary bees and wasps. In nest cells, the mites attempt to kill eggs or developing bees, and then feed on available pollen. If the host survives the mite attacks, the mites will also feed on host waste.
• Phoretic deutonymphs (non-feeding stage) disperse on adult bees from one nest to another. Kleptoparasitic bees and wasps can also be used as transport.

In Japan, an undescribed species of Tortonia was found to be a kleptoparasite of Osmia cornifrons, an important pollinator of apple trees (Qu et al., 2002; Qu et al., 2003): after infesting cells and prior to feeding on the stored pollen-mass, Tortonia sp. killed hosts, but only if the hosts were at stages egg to early third instar larva. The success of killing the host appears to positively depend on mite population sizes. Bees that survived formed normal cocoons.

Feeding stages and phoretic deutonymphs hibernate in bee nests. Protonymphs of Tortonia sp. that encountered shortages of food molted to phoretic deutonymphs. The percentage of phoretic deutonymphs phoretic on bees is lower (6.6% in total) as compared to Chaetodactylus.

Tortonia sp., when co-inhabiting with Chaetodactylus nipponicus in the same cell, shows lower population sizes, indicating its lower competitive ability. However, in cells with living hosts, the ratio of individual numbers of Tortonia sp. was higher than that of Ch. nipponicus, because the former can survive by feeding on host feces.

In the USA, mortality of developing wasps Monobia quadridens in cells infested with feeding stages of Tortonia quadridens has been observed, but the ultimate cause of death remains unknown. Mites have appeared to act as scavengers feeding on organic debris in the nests (Krombein, 1962; Krombein, 1967). Similarly, all stages of Tortonia quadridens were found in a nest of Xylocopa virginica, on and in the pollen balls in empty (failed) cells. The ultimate cause of cell failure remains uncertain. These authors called Tortonia kleptoparasitic (Lombert et al., 1987).