Molecular identification of Stylops advarians (Strepsiptera: Stylopidae) in western Canada.

Strepsiptera are an enigmatic order of insects with extreme sexual dimorphism which makes it difficult to "match-up" free-living adult males with parasitic conspecific females of the Stylopidia, and free-living females of the Mengenillidae using morphological characters. Species identification is further complicated for the Stylopidia because adult females are endoparasitic and neotenic. Therefore, we used DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) to confirm the species identity of adult strepsipterans that were morphologically identified as Stylops advarians. These specimens, collected from Saskatoon (Saskatchewan, Canada), included one adult male, and eight females, the latter of which had been collected from solitary bees (Andrena milwaukeensis). Also included in the analyses were three pools of first-instar larvae that had emerged from three of the females. The results of the molecular analyses revealed that all specimens had an identical cox1 sequence, and belonged to a clade, with total statistical support (bootstrap value of 100%), that contained specimens of S. advarians from New York and Maine (USA). Hence, the results were consistent with the morphological identification of S. advarians. This study demonstrates the usefulness of a molecular approach for the identification of endoparasitic adult female and larval strepsipterans, life cycle stages that lack significant morphological characters for species identification.

Description of the Adult Male of Stylops nubeculae Pierce (Strepsiptera: Stylopidae), a New Record for Canada.

The morphology of the adult male of Stylops nubeculae Pierce, encountered in stylopized gasters of two adult bees of Andrena peckhami, is described for the first time. This species was previously known only from the endoparasitic adult female found in Colorado, USA. We report a new locality for this species in Alberta, Canada.

Description of the Adult Male of Stylops advarians Pierce (Strepsiptera: Stylopidae).

The morphology of the adult male of Stylops advarians Pierce is described for the first time. This species was previously known only from the endoparasitic adult female and the host-seeking, first-instar larva. Members of Stylops are cosmopolitan, and Stylops advarians can be found parasitizing Andrena milwaukeensis Graenicher in western Canada.

Adaptive morphology of the host-seeking first-instar larva of Stylops advarians Pierce (Strepsiptera, Stylopidae), a parasite of Andrena milwaukeensis Graenicher (Hymenoptera, Andrenidae).

The morphology of the prognathous, host-seeking first-instar larvae of Stylops advarians was examined to advance our understanding of their adaptations to reach immature bee hosts, a process requiring temporal phoresy on an adult bee. Sensory structures on the larval head, including eye spots and two pairs of olfactory pits, evidently assist recognition of an adult bee and eventual detection of a permanent host within a nest cell. First-instar larvae utilize various features of their appendages to travel securely on their phoretic host. Flexible adhesive tarsi of the pro- and mesothoracic legs allow them to embark and be retained on a flying bee. The tips of the pair of caudal filaments appear modified for a similar purpose. Spinulae of two lengths, and arranged in distinct patterns, cover the posterior edges of the thoracic and abdominal segments both dorsally and ventrally. These projections can cause lodging of larvae in the plumose hairs of the phoretic host, and may lock into the exine of pollen collected by the foraging bee. Discovery of a first-instar larva partially packed into a pollen load and in the crop of Andrena milwaukeensis demonstrates that Stylops is adapted to travel with a phoretic host both externally and internally.