Visiting insect diversity and visitation rates for two globally-imperiled plant species in Colorado’s Mosquito Range

Ipomopsis globularis (Globe gilia), and Saussurea weberi (Weber's saussurea) are globally imperiled plant species known only from geographically restricted areas in alpine habitats of the Rocky Mountains. These species were observed in the Mosquito Range of Colorado to determine the diversity of insect visitors (potential pollinators) and approximate insect visitation rates. Ipomopsis globularis was visited primarily by fly and ant species; and in general, the insects visited at a rate of about 0.83 visits/open corolla/30 minutes. Saussurea weberi was visited primarily by flies, and also by bees, supporting the research of Abbott (1998). S. weberi was observed to have an insect visitation rate of about 0.14 visits/open corolla/30 minutes. Rare, geographically restricted species are particularly susceptible to human disturbances that would reduce the frequency and/or diversity of potential pollinator visits. Management plans for these plant species should consider the ecology of associated insect visitors, which may play an important role in their pollination ecology. Further information is needed before thorough conservation strategies can be developed.