BEES IN THE WOODS: SPRING ORCHARD POLLINATORS USE FOREST CANOPY POLLEN

There are over 4,000 wild bee species native to the United states, and over 420 in New York State; many are in decline due to combined pressures of habitat loss, pesticides, and pathogens. Despite many habitat restoration efforts focused on meadows and wildflower strips, the Northeastern United States is historically forested. Research consistently finds that bee abundance, richness, and crop yields are higher near forests despite their common perception as inhospitable for bees. Inspired by anecdotal reports that bees collect wind-pollinated canopy pollens, we set out to better understand the presence, activity, and behavior of bee communities in early spring forests. We worked in orchard-adjacent temperate deciduous forests in the Northeastern US, and used a suite of novel methods, including tree climbing, canopy trapping, and extensive palynology of adult bee and hover fly digestive tracts. First, we report on surprisingly high pollinator activity, abundance, and diversity in the canopy, and a much higher proportion of female bees in the canopy. Bee and hover fly diets similarly revealed that canopy-caught bees were more likely to have eaten large amounts of pollen than bees caught in the understory, but that canopy pollen itself was mostly eaten by bees caught in both forest strata. Failing to sample in the canopy underestimates the importance of canopy pollen to adult bee diets. Diet profiles revealed active vertical movement within forests as well as temporal “spillover” from the understory, to the canopy, to the orchard. Within Andrena, effective orchard pollinators, we found that male bees were restricted to the forest, and thus suggest that forests may be important in order to conserve these species in agricultural systems. Finally, we explore how pulsed "mast-bloom" events leave signatures on spring pollen diets, and the role of this extra layer of resource heterogeneity for early-spring bees. Sugar maple mast bloom in 2019 but not 2018 led to both a proportional and absolute increase in pollen consumption. We reflect on forest and landscape-scale management recommendations, and encourage a more expansive appreciation of the many ways in which forests are important for pollination services and wild bee conservation.

Name thesis:degree_name

Ph. D., Entomology

Level thesis:degree_level

Doctor of Philosophy

Discipline thesis:degree_discipline

Entomology

Grantor

Cornell University

Year dc:date.issued

2022

Author dc:creator

• Urban-Mead, Katherine Ruth

Committee members dc:contributor.committeemember

• McArt, Scott
• Poveda, Katja Andrea

• Andrena
• bees
• canopy
• forest
• pollen
• pollinators

Language dc:language.iso

en

DOI

https://doi.org/10.7298/h1x8-7556

Dc Identifier Other

ProQuest Submission ID: 13022
ProQuest Publication ID: 29166617

OAI identifier oai:identifier

oai:ecommons.cornell.edu:1813/111806