Degree-day models for development of the dung beetles Onthophagus nuchicornis, O. taurus, and Digitonthophagus gazella (Coleoptera: Scarabaeidae), and the likelihood of O. taurus establishment in southern Alberta, Canada

Three studies were performed to assess the likelihood of establishing the dung beetle Onthophagus taurus (Schreber) (Coleoptera: Scarabaeidae) in southern Alberta, Canada. This European species was first reported in Florida in the 1970s and now occurs as far north as Michigan, United States of America. Its ability to establish in Canada is unknown, but is desired to accelerate the degradation of cattle dung on pastures. The first study examined egg-to-adult development at temperatures of 10-32 °C (in increments of 2 °C) to develop degree-day models for O. taurus and for two other closely related species of dung beetles. Onthophagus nuchicornis (Linnaeus), used as a positive control, is a European species common across Canada. Digitonthophagus gazella (Fabricius), used as a negative control, is an Afro-Asian species whose distribution is restricted in North America to the southern United States of America. The second study examined the overwintering ability of O. taurus and D. gazella in outdoor field cages. The third study compared climate parameters between southern Alberta and the northernmost recorded distribution of O. taurus. Results combined across the three studies show that O. taurus can complete egg-to-adult development and overwinter in southern Alberta. However, high overwintering mortality is predicted to prevent establishment of O. taurus in the region. © Her Majesty the Queen in Right of Canada 2014.