Shuler Rachel E, Roulston Tai H, Farris Grace E
Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904-4123, USA.
J Econ Entomol. 2005 Jun;98(3):790-5. doi: 10.1603/0022-0493-98.3.790.
Recent declines in managed honey bee, Apis mellifera L., colonies have increased interest in the current and potential contribution of wild bee populations to the pollination of agricultural crops. Because wild bees often live in agricultural fields, their population density and contribution to crop pollination may be influenced by farming practices, especially those used to reduce the populations of other insects. We took a census of pollinators of squash and pumpkin at 25 farms in Virginia, West Virginia, and Maryland to see whether pollinator abundance was related to farming practices. The main pollinators were Peponapis pruinosa Say; honey bees, and bumble bees (Bombus spp.). The squash bee was the most abundant pollinator on squash and pumpkin, occurring at 23 of 25 farms in population densities that were commonly several times higher than that of other pollinators. Squash bee density was related to tillage practices: no-tillage farms hosted three times as great a density of squash bees as tilled farms. Pollinator density was not related to pesticide use. Honey bee density on squash and pumpkin was not related to the presence of managed honey bee colonies on farms. Farms with colonies did not have more honey bees per flower than farms that did not keep honey bees, probably reflecting the lack of affinity of honey bees for these crops. Future research should examine the economic impacts of managing farms in ways that promote pollinators, particularly pollinators of crops that are not well served by managed honey bee colonies.
近期，人工饲养的西方蜜蜂（Apis mellifera L.）蜂群数量下降，这使得人们对野生蜜蜂种群在当前及未来对农作物授粉的贡献愈发关注。由于野生蜜蜂常栖息于农田，其种群密度及对作物授粉的贡献可能会受到耕作方式的影响，尤其是那些用于减少其他昆虫种群数量的方式。我们对弗吉尼亚州、西弗吉尼亚州和马里兰州的25个农场的南瓜授粉者进行了普查，以探究授粉者数量是否与耕作方式有关。主要授粉者有南瓜切叶蜂（Peponapis pruinosa Say）、蜜蜂和熊蜂（Bombus spp.）。南瓜切叶蜂是南瓜上数量最多的授粉者，在25个农场中的23个农场都有出现，其种群密度通常是其他授粉者的几倍。南瓜切叶蜂的密度与耕作方式有关：免耕农场的南瓜切叶蜂密度是翻耕农场的三倍。授粉者密度与农药使用无关。南瓜上的蜜蜂密度与农场中人工饲养的蜜蜂蜂群数量无关。有蜂群的农场每朵花上的蜜蜂数量并不比不养蜜蜂的农场多，这可能反映出蜜蜂对这些作物缺乏偏好。未来的研究应考察以促进授粉者，特别是那些人工饲养的蜜蜂蜂群授粉效果不佳的作物的授粉者的方式管理农场所产生的经济影响。
