Recent Topics Posters
Caswell, Wade D. , Davis, Arthur R. .
Evaluating insects as pollinators of virgin flowers of tristylous purple loosestrife (Lythrum salicaria L.) by pollen tube fluorescence.
Relatively little is known about the pollination biology of purple loosestrife (Lythrum salicaria) in Saskatchewan, the final Canadian province to have been invaded. The objectives of this project were to discriminate mere flower visitors from pollinators of this invasive species, and to quantitatively rank such insect pollinators on the basis of their pollination effectiveness and foraging speed. At three field sites utilized in each of 2006 and 2007, previously-unvisited (virgin) flowers were carefully unbagged to expose them to visitors. Upon departure of the forager, spikes were carefully rebagged to prevent further visits. Styles from these once-visited flowers were harvested 24 h later, fixed, stained with aniline blue, and examined microscopically for the fluorescence of callose typical of pollen tubes. Insect identity, foraging behaviour, duration of visit and quantities of pollen tubes per style base were recorded for approx. 230 such visits. Trials involving selfing; the transfer of legitimate and illegitimate pollen; plus non-visited (control) flowers, were also performed and styles examined. Using this methodology, it was determined that up to 7 species of bumble bees (Bombus spp.) and the European honey bee (Apis mellifera) ranked as top pollinators, followed by Lasioglossum spp. (Halictidae) and Megachile spp. (Megachilidae). However, various species of hover flies (Syrphidae) were found to pollinate Lythrum poorly.
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1 - University of Saskatchewan, Biology, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada
Presentation Type: Recent Topics Poster
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM