Abstract
Microgastrinae wasps (Hymenoptera, Braconidae) from the city of Ottawa and its surroundings (a 50-km radius circle, ~7,800 km(2)) were studied based on 1,928 specimens collected between 1894 and 2010, and housed in the Canadian National Collection of Insects. A total of 158 species from 21 genera were identified, which is by far the highest number of species ever recorded for a locality in North America. An annotated checklist of species is provided. Choeras parasitellae (Bouché, 1834) and Pholetesor nanus (Reinhard, 1880) are recorded for the first time in the Nearctic (previously only known from the Palearctic region), Cotesia depressa (Viereck, 1912) is recorded for the first time in Canada (previously only known from the United States), and Cotesia hemileucae (Riley, 1881) and Protapanteles phlyctaeniae (Muesebeck, 1929) are recorded for the first time in the province of Ontario. In Ottawa the most diverse genera are Cotesia, Apanteles, Microplitis, Pholetesor, Microgaster, and Dolichogenidea, altogether comprising 77% of the species found in the area. A total of 73 species (46%) were represented by only one or two specimens, suggesting that the inventory for Ottawa is still relatively incomplete. Seasonal distribution showed several peaks of activity, in spring, summer, and early fall. That general pattern varied for individual species, with some showing a single peak of abundance either in the summer or towards the end of the season, others species attaining two peaks, in late spring and late summer, or in early summer and early fall, and yet others attaining up to three different peaks, in spring, summer and fall. At least 72 of the Microgastrinae species from Ottawa have been previously associated with 554 species of Lepidoptera as hosts - but those historical literature records are not always reliable and in many cases are based on data from areas beyond Ottawa. Thus, our knowledge of the associations between the 158 species of microgastrine parasitoids and the caterpillars of the 2,064 species of Lepidoptera recorded from Ottawa is still very incomplete.