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Bumblebee Foraging on Cowpeas in Kenya
Achievement/Results
Long-distance pollen flow assessment through evaluation of pollinator foraging range suggests transgene escape distances
Rémy S. Pasquet, Alexis Peltier, Matthew B. Hufford, Emeline Oudin, Jonathan Saulnier, Lénaic Paul, Jette T. Knudsen, Hans H. Herren, Paul Gepts. 2008, Proc. Nat’l Acad. Sci. 105:13456-13461
Foraging range, an important component of bee ecology, is of considerable interest for insect-pollinated plants because it determines the potential for outcrossing among individuals. However, long-distance pollen flow is difficult to assess. Pollen movement can be estimated indirectly through population genetic data, but complementary data on pollinator flight distances is necessary to validate such estimates. Trainee Matthew Hufford, trainer Paul Gepts, and their collaborators radio-tracked the bee pollinators of cowpeas (Vigna unguiculata) and found that carpenter bees visiting cowpea flowers can forage up to six km from their nest. They found foraging distances to be shorter than the maximum flight range, especially under adverse weather conditions or poor reward levels. From complete flight records in which bees visited wild and domesticated populations, they concluded that bees can mediate gene flow and, in some instances, allow transgene (genetically engineered material) escape over several kilometers.
Address Goals
Cowpeas provide a major source of protein for many human populations in Africa. However, damage to cowpeas by crop pests greatly reduces the harvest of this food source. As a result, there has been considerable effort in producing cultivars of cowpea that incorporate the Bt gene and thus have enhanced resistance to insect damage.
Hufford and collaborators found bees ranging up to 6km from their nests which suggests a potential escape distance for transgenes from cultivated fields of cowpea to wild cowpea. This has been of particular concern in Kenya due to the impending release of a transgenic, insect-resistant cultivar of cowpea. Such mixing of genomes of transgenic cowpea with wild relatives could affect weed control efforts and thus reduce the positive impacts of transgenic cowpea on the food supply
