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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #337374

Research Project: Agricultural Landscape, Pollinator Behavior and Gene Flow Risk

Location: Vegetable Crops Research

Title: Enhancing pollination by attracting & retaining leaf cutting bees (Megachile rotundata) in alfalfa seed production fields

Author
item Brunet, Johanne
item Syed, Zainulabeuddin - University Of Notre Dame

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/23/2017
Publication Date: 1/29/2017
Citation: Brunet, J., Syed, Z. 2017. Enhancing pollination by attracting & retaining leaf cutting bees (Megachile rotundata) in alfalfa seed production fields. Proceedings for the 2017 Winter Seed School Conference, January 29-31, 2017, Las Vegas, Nevada p. 67-73.

Interpretive Summary:

Technical Abstract: The alfalfa leafcutting bee, Megachile rotundata (F.), has become an important managed pollinator of alfalfa, Medicago sativa L. One problem when using alfalfa leafcutting bees as managed pollinator, is the dispersal of many females upon release, even when adequate nesting sites are present. While dispersal of female bees from the site of emergence may represent a successful evolutionary adaptation to avoid inbreeding, this behavior becomes problematic when these pollinators are used as managed pollinators of alfalfa. Reducing the dispersal of females upon release into the fields, would facilitate the maintenance of viable commercial populations of alfalfa leafcutting bees. While female leafcutting bees prefer old, relative to new nesting boards, the use of old nesting boards is not a viable option because it facilitates disease propagation and increases bee mortality. Odors emitted from old nest contents could influence the preference of bees for older nesting boards and the use of chemical attractants may offer a viable alternative to retain female bees at a site. The objectives of this research were, therefore, to extract and isolate the biologically active constituents from empty alfalfa leafcutting bee cells (where eggs were laid and bees developed) and to quantify the attraction of these chemicals to the bees. If positive behavioral responses are detected, we will identify the biologically active constituents using bee’s antenna as a biological detector. Long range attractants (LRA) and short range arrestants (SRA) were isolated from empty bee cells and behavioral tests were performed to quantify attraction of the different extracts to alfalfa leafcutting bees. When individually tested against a control, we observed no preference of leafcutting bees for either long range attractants or short range arrestants. Bees visited the bee boards with solvent (control) as frequently as the bee boards with the chemical being tested. Due to the lack of positive behavioral responses, we did not conduct identification of the biologically active constituents using bee’s antenna as a biological detector. Although more behavioral tests would help confirm the generality of these findings, the behavioral responses obtained to date do not support the utility of field deployable attractive baits, using the attracting chemicals from empty bee cells, to facilitate the maintenance of alfalfa leafcutting bees in seed-production fields and improve alfalfa pollination.