Genus: Radoszkowskiana Popov, 1955
Common name: none
Radoszkowskiana are cleptoparasites that range in body length from 10–13 mm. Females have a red abdomen, while males have a black abdomen (Michener 2007). Female’s second abdominal segment is the widest and tapers posteriorly (Michener 2007).
Radoszkowskiana consists of four species (Michener 2007); none are known to occur in the U.S. or Canada.
(modified from Michener 2007)
Radoszkowskiana may be confused with species in the genus Coelioxys due to tapering of the abdomen after the second segment in females, lack of scopa, and presence of preoccipital carina on the side of the head (Michener 2007). Radoszkowskiana males may also be confused with Megachile due to the blunt shape of T6, and rounded axilla (Michener 2007). Radoszkowskiana can be differentiated from these two genera based on the combination of distinguishing characteristics listed above. In addition, larval Radoszkowskiana can be differentiated from Coelioxys by the curvature of the first instar’s mandibles: Radoszkowskiana curve orally, while Coelioxys bend caudally (Rozen and Kamel 2008). Further, Radoszkowskiana can be differentiated from Megachile by the lack of ventral scopa (Ozbek and Schwarz 2016).
There are no known invasives.
Radoszkowskiana is a group of cleptoparasitic bees whose only known host is Megachile nigripes (Rozen and Kamel 2007). Radoszkowskiana feed on their own chorion and the host’s yolk as first instar larvae (Rozen and Kamel 2007).
Female R. rufiventris lay their eggs in host nests of Megachile nigripes by either opening closed nests or, more likely, by entering the nest when the host is away (Rozen and Kamel 2007). Once in the nest, the female R. rufiventris lays an egg on top of the host egg, which is known to develop more slowly (Rozen and Kamel 2008). Once the cleptoparasite’s egg hatches, the larva kills the embryonic host by biting it with short, fang-like mandibles and then consumes its own chorion while staying on top of the dead host egg (Rozen and Kamel 2008).