Pollinators in AgroEcosystems

Melanie DuboisScience & Technology BranchAgriculture Agri-Food Canada

December 17 2020Brandon

Pollinators - Bees• Basics: species,

biology, habitat

• Role of pollinators & habitat

• Supports for pollinators

• Gaps in knowledge

Macropis nuda – miner bee

Why the focus on bees?

• Bees actively collect and transport pollen to feed their young

• Bees exhibit flower constancy

Status: ↓/?

Trends: ↘→?

Drivers: √/?

Thresholds: ?

Photo: C. Goertzen AAFC

Basic bee literacy is lacking• Most think there are 2

kinds of bees – honey and bumble

• Challenge to broaden to native bees - mass media focus on honey bee (15% articles mention native bees)

• Different pressures, different solutions.

Photos: NYTimes

Manitoba has ~218 species of bees

• Canada ~797 spp.

• US ~3,600 spp.

• Worldwide ~20,000

Andrena sp

24 species of bumble bee

Bombus huntii, rufocinctus, ternarius

European Honey Bees are not

endangered in North America.

USA: 2005-2014 # of hives increased from 2.4m to 2.75m

The problems for wild bees are different than honey bees.

• Honey bees came from Europe and live on farms like cows, sheep & goats.

• Wild bees don’t make honey and take care of themselves like deer, elk & polar bears.

Photos: NYTimes

Groups based on habitatGround-nesting bees ~80%

Stem/wood-nesting bees ~20%

Bumble bees ~1%

Bees are in decline

• 1 in 4 bumble bees at risk of extinction

• Canada:

– SARA listed species: Rusty Patched BB

– COSEWIC: Gypsy BB, Western BB (2 subspecies), Yellow-banded BB, Macropis Cuckoo bee, Sable Island Sweat bee

• 70% of the 124 main crops directly for human consumption (worldwide)

• 39% of food crop production value(worldwide)

• Many of our necessary vitamins and minerals come from insect-pollinated plants

• Over $3 billion/yr in Canada, $18 to $27 billion value of crops in U.S. ($217 billion worldwide)

Photo: Whole Foods Market

Pollinators are critical to agricultural production & human health

Source: Morse and Calderone 2000; Klein et al. 2007; Eilers et al. 2011

We would survive but with health impacts, food scarcity, insecurity and

limited coffee or chocolate.

Your options without pollinators Photo: Whole Foods Market

Economics• 300% increase globally,

crop acres 2X

• CAN/US tied 4 of 16 vulnerability to loss

• Yield increases from innovation lower for crops with pollinator dependency

• Highest dependency:– Fruit & vegetables

– Edible oil crops

– Stimulants (coffee, chocolate)

– Nuts & spices

Photo: M Dubois AAFC

Crop production limited by lack of pollinators

• Yield shown to be limited in 5 of 7 pollinator dependent crops studied

• Overall contribution of wild bees = or > honey bee by factor of 1.4 to 3.2

Reilly, J. R., et al. "Crop production in the USA is frequently limited by a lack of pollinators." Proceedings of the Royal Society B 287.1931 (2020): 20200922.

Complex landscapes positively associated with crop yields

• Alberta study looked at over 250000km of croplands found that those with semi-natural areas had higher field-level yields

• Shown over large ag region over multiple years (2012-2017), crops and varieties

Galpern, Paul, et al. "Landscape complexity is associated with crop yields across a large temperate grassland region." Agriculture, Ecosystems & Environment 290 (2020): 106724.

Native bees improve pollination and yield.Dependence on

insect

pollination

varies between

crops.

Managed bees

common in:

• Hybrid canola

seed

• Blueberries

• Fruit trees

• Squash

• Tomatoes

Crop Recommended number of honey bee hives per ha (literature average)

Relative insect pollinator requirement (where 1.0 = most pollinator intensive crop (i.e. onion seed))

Onion seed 16.50 1.00Strawberry 8.60 0.52Alfalfa seed 7.90 0.48Clover (red) 7.70 0.47Cranberry 7.60 0.46Blueberry 7.50 0.45Carrot seed 7.50 0.45Clover (sweet) 7.20 0.44Blackberry 6.70 0.41Clover (crimson) 5.60 0.34Cucumber 5.50 0.33Cabbage seed 5.00 0.30Hybrid canola seed 5.00 0.30Clover (alsike) 4.80 0.29Cherry (sweet) 4.20 0.25Asparagus seed 4.00 0.24Squash 3.80 0.23Apple 3.70 0.22Clover (white) 3.70 0.22Pear 3.70 0.22Plum and prune 3.20 0.19Bean (lima) 2.50 0.15Cherry (sour) 2.50 0.15Sunflower 2.10 0.13Peach and Nectarine 2.00 0.12Raspberry 2.00 0.12Soybean 1.40 0.08Bean (common) 0.00 0.00Beet seed 0.00 0.00

Pollinators & Canola

• Has shown to increase seed yield by as much as 46%

• Improves seed set uniformity

• Benefits to yield from insects increases in nitrogen limited systems

• Ideal amount of native bee habitat 30%

Causes of Pollinator Declines

• Climate change

• Pesticides

• Habitat loss & fragmentation

• Diseases and parasite transmission from managed bees

Climate Change Impacts

• bee distribution

• Plant phenologies –spring emergence 10 days earlier causing de-synchronization

• Species interactions

• Increased storms

Amount of suitable habitat is the main driver of pollination potential in agroecosystems.

Habitat must supply• Suitable

nesting & overwintering substrate

• Access to forage season-long

• Protection from threats –tillage/ pesticides

Photo: M Dubois AAFC

TAXA APRIL MAY JUNE JULY AUG SEP OCT

Plaster Bees (Colletesinaequalis, validis)

Mining Bees (Andrena spp.)

Green Sweat Bees (Augochlora pura)

Green Sweat Bees (Augochlorella striata)

Sweat Bees (Halictus spp.)

Sweat Bees (Lasioglossumspp.)

Mason Bees (Osmia spp.)

Bumble Bees (Bombus spp.)

Native Bees need pollen and nectar before and after crop bloom.

© Data from Steve Javorek, Agriculture Canada

Example: flight periods of native bees in relation to canola bloom.

Habitat is Key for native bees

Habitat fragmentation

Habitat as Proxy Pollinator Indicator

• Lack an indicator for pollinators

• Needs to be accurate, repeatable, and relevant at multiple scales

• Currently rely on intensive sampling & expert opinion

Wildlife Habitat Capacity on Agricultural Lands

Epic Pollination Potential Indicator (EPPI)

• Developed around the InVEST Canadian parameters – relative abundance

• assess and map pollination potential - the capacity of the ecosystem to deliver pollination services in ag systems.

• shows low pollination services potential in areas that have higher intensity land-use

Habitat Assessment – what do you already have?4 major components are assessed:

1. Landscape-scale vegetation zones

2. Availability and quality of bee forage (spring, summer, fall)

3. Availability and quality of nesting habitat (well drained, untilled, cavities, wood, pithy/hollow stems)

4. Farm management practices

How can we support pollinators?• Pragmatic solutions

must be economically viable

– direct benefit to producers

– BMPs/EGS subsidies for solutions with high public benefits

• Stacked benefits: pollination, carbon, erosion control, wildlife habitat, water quality

Photo: Jennifer Hopwood

Habitat in ag land can take on multiple forms• Field Border Plantings; Conversion of Fallow

Areas

• Pollinator / Insectary Strips

• Cover crops

• Flowering hedgerows

• Filter Strips

• Understory Plantings

• Drift Protection (non-flowering hedgerows)

Gaps in knowledge

• Baseline maps of pollinators

• Impact of tillage on ground nesters

• Threshold of disturbance & how much habitat is enough

• Appropriate and successful seed mixes

Thank you

• Questions?

Dog taxPhoto M Dubois