Department of Biology, University of Massachusetts, Amherst, MA 01003;
Ecology Program Area, Department of Biology, San Diego State University, San Diego, CA 92182.
Proc Natl Acad Sci U S A. 2020 May 26;117(21):11559-11565. doi: 10.1073/pnas.2000074117. Epub 2020 May 11.
Pathogens pose significant threats to pollinator health and food security. Pollinators can transmit diseases during foraging, but the consequences of plant species composition for infection is unknown. In agroecosystems, flowering strips or hedgerows are often used to augment pollinator habitat. We used canola as a focal crop in tents and manipulated flowering strip composition using plant species we had previously shown to result in higher or lower bee infection in short-term trials. We also manipulated initial colony infection to assess impacts on foraging behavior. Flowering strips using high-infection plant species nearly doubled bumble bee colony infection intensity compared to low-infection plant species, with intermediate infection in canola-only tents. Both infection treatment and flowering strips reduced visits to canola, but we saw no evidence that infection treatment shifted foraging preferences. Although high-infection flowering strips increased colony infection intensity, colony reproduction was improved with any flowering strips compared to canola alone. Effects of flowering strips on colony reproduction were explained by nectar availability, but effects of flowering strips on infection intensity were not. Thus, flowering strips benefited colony reproduction by adding floral resources, but certain plant species also come with a risk of increased pathogen infection intensity.
病原体对传粉者的健康和粮食安全构成重大威胁。传粉者在觅食时可能会传播疾病，但植物物种组成对感染的后果尚不清楚。在农业生态系统中，常使用开花带或树篱来增加传粉者栖息地。我们以油菜为重点作物，在帐篷中进行操作，并使用我们之前在短期试验中表明会导致更高或更低蜜蜂感染的植物物种来操纵开花带的组成。我们还操纵了初始群体感染，以评估其对觅食行为的影响。与低感染植物物种相比，使用高感染植物物种的开花带使熊蜂群体感染强度几乎增加了一倍，而仅在油菜中则为中等感染。感染处理和开花带都会减少对油菜的访问，但我们没有证据表明感染处理改变了觅食偏好。尽管高感染的开花带增加了群体感染强度，但与仅种植油菜相比，任何开花带都能提高群体繁殖力。开花带对群体繁殖的影响可以用花蜜供应来解释，但开花带对感染强度的影响却不能。因此，开花带通过增加花卉资源使群体繁殖受益，但某些植物物种也会带来增加病原体感染强度的风险。
