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Edge Interior

Boosting forage for bees in regions of almond productionNeal M. Williams, Kimiora L. Ward, Staci N. Cibotti

Department of Entomology and Nematology, University of California - Davis

Background

Goals1. Quantify bloom timing of wildflower and mustard

forage plantings in Central and Northern

California regions of almond production.

2. Measure honey bee and wild bee use of forage

plantings before, during, and after almond bloom.

3. Quantify competition for pollinator visitation

between flower plantings and orchard.

Summary

Floral display of mustard and wildflower plots coincided

with almond bloom and extended floral resources for bees.Almond production relies on robust bee

populations, yet bee keepers and researchers identify

the lack of diverse nutrient sources as a primary

threat to bees. Habitat plantings are used to boost

forage resources for honey bees; however, several

interconnected issues remain to be resolved in this

approach. (1) Few data exist on the effectiveness of

various plant options for supporting bees in the

orchard context. (2) Bee use of plantings has not

been thoroughly tested in northern regions of almond

production. (3) Potential for habitat plantings to

impact almond pollination through competition or

facilitation of pollinators has not been explored.

Results

We gratefully acknowledge support of the

Almond Board of California.

This work forms part of ongoing

collaboration with PAm.

Study Locations

• Sites planted with wildflower mix October -November 2015. Mustard sites annually reseeded fall 2015 and 2016

• Monitored floral densities of each forage plant species bi-weekly from Feb - April

• Monitored bee use of plantings on the same days we assessed floral resources

• Assessed the potential for competition during almond bloom with weekly samples of bee visitation to forage-enhanced orchards compared to control orchards

• Quantified nut set from trees on edge and interior of orchards adjacent forage plantings and control borders

Ho

ney

Be

e V

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2016 2017

Blue circles show wildflower sites, yellow circles PAm mustard mix

sites, red squares typical controls, and purple squares riparian

controls.

Methods

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Bees visited forage plots significantly more than unplanted

orchard borders.

2016

2016 2017

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0.00 1.00 2.00 3.00 4.00Edge Interior

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Honey bee visitation to almond orchards was improved by

habitat plantings. Increased visitation improved nut set in

wildflower-enhanced orchards, but not in mustard-enhanced

orchards.

Alm

on

d B

loo

m

Feb Mar Apr Feb Mar Apr

Feb Mar Apr

Feb Mar Apr

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Feb

Mar

Mar1. Wildflower and mustard plantings outperformed

control borders and provided resources to bees

during and after almond bloom without detracting

from visitation to the orchard.

2. Annually reseeded mustard plots had higher floral

resources and honey bee use than wildflowers in

the second year. Fall wildflower reseeding may

improve performance.

3. Mustard-enhanced orchards had the highest

rates of bee visitation to almond, but no increase

in nut set, while wildflower-enhanced orchards

had higher nut set in the orchard interior.

4. Annually reseeded wildflower plantings may be

the top strategy for improved honey bee

pollination in the presence of wild bees.