Multiple stressors

Multiple Stressors:

Bees as a case study

Dr. Jeff Pettis

USDA- ARS Bee Research Lab

Beltsville, MD USA,

Talk Outline:

* Pollinator decline and honey bees

* Bee Biology

Honeybees, bumblebees, solitary bees

* Challenges to risk assessment

* Pesticides and honey bees during pollination

* Neonic field study in Sweden

* Conclusions

Colony Collapse Disorder (CCD) in US

captured the media and worlds attention in 2007

Honey Bee Diseases and Pests

Nosema a gut parasite

Virus

Parasitic Varroa mites American foulbrood disease

Honey bees Large colonies

30,000 individuals

Solitary bee No colony 1 female

Bumble bees Small colonies 300 individuals

Honey bees Long lived

Store honey and pollen for winter

Solitary bee Annual Queens or pupae overwinter

Bumble bees Annual Queens overwinter

Honey bees Store pollen and nectar

large flight range 5-10km

Solitary bee Store pollen ball with egg short flight range 0.5-1km

Bumble bees Store pollen and nectar short flight range 0.5-1km

Challenges to Risk Assessment

Need to protect all pollinators? Are honey bees the best model? Means to test multiple lines of evidence

Courtesy of the Washington Post

Pollination, diversity and honey production

are all EPA protection goals

Challenges to Risk Assessment

No CLEAN stock (mites and diseases) How to test Multiple stressors Individual testing, Does it relate to colony?

Varroa mite

Towards holistic approaches to the risk assessment of

multiple stressors in bees

olloquium N°17 on low dose response

in toxicology and risk nt

EFSA Scientific Colloquium No.18, Parma, 15-16 May

2013

EFSA Scientific Colloquium No. 18

Challenges to Risk Assessment

Individual testing vs. colony testing? Individual testing: easy to control , measurable end points but does it predict colony outcomes ?

Photo by M. Frazier

Solitary bees

e.g. Osmia Alfalfa Leafcutter Bees

Bumblebees

Honey bees

Stingless Bees

Ground

Nesting

Bees

Crop pollination exposes honey

bees to pesticides which alters

their susceptibility to the gut

pathogen Nosema

Jeff Pettis

USDA- ARS Bee Research Lab

Beltsville, MD USA

Dennis vanEngelsdorp and

Elinor Lichtenberg

Univ. of Maryland

Collected pollen on 6 crops, almonds, apples, blueberry,

cranberry, cucumber and watermelon

Experimental setup:

Field component:

Pollen traps used to collect pollen

from bees on seven crops

Identified pollen to plant type

Analyzed pollen for pesticide residues

Experimental setup:

Field component:

Pollen traps used to collect pollen

from bees on seven crops

Identified pollen to plant type

Analyzed pollen for pesticide residues

Laboratory component:

Fed newly emerged workers on crop

collected pollen

Challenged bees with

the gut parasite Nosema

Dissected bees after 12 days

counted Nosema spores

Pollen collection from the crop where a hive was located was low for most crops.

Pettis JS, et al. (2013) Crop Pollination Exposes Honey Bees to Pesticides Which Alters Their Susceptibility to the Gut Pathogen

Nosema ceranae. PLoS ONE 8(7): e70182. doi:10.1371/journal.pone.0070182

Pesticide diversity found in pollen samples, but not pesticide load, varied by crop.

Fungicide and neonicotinoid diversities varied by crop.

How to deal with:

Multiple stressors?

In this case multiple pesticides

in different combinations

Laboratory component:

Fed newly emerged workers on crop

collected pollen

Challenged bees with

the gut parasite Nosema

Dissected bees after 12 days

counted Nosema spores

Relative Risk

• Smoking

– Lung Cancer

• RR: 230

– Coronary Disease

• RR: 3 – 4

Nosema spores in the mid-gut of adult honey bees, similar to Giardia in humans

Relative risk of Nosema infection

with selected pesticides

Chlorothalonil 2.31

Pyraclostrobin 2.85

Captan 0.59

Bifenthrin 2.08

Fluvalinate 2.43

Imidacloprid 0.31

Plants

Pesticides

Pollinators

Pathogen

interactions

Swedish oilseed rape (canola) study

16 plots of 5? hectares each Rundlof et al. Nature 521:77-80 2015

Clothianidin seed treated canola

Honey bees

Bumblebees

Solitary bees

Swedish canola study : Rundlof et al. Nature EPA in US test in 3 areas Swedish study uses 8 sites

Figure 1: Paired design with replicated landscapes.

16 plots total

8 paired sites

virgin soil (re: seed treatments)

6 honey bee colonies per plot

Swedish canola study: Rundlof et al. Nature EPA in US test in 3 areas Swedish study uses 8 sites

Figure 3: Bumblebee colony development.

Mean (± 95% confidence limits) bumblebee colony weight change (g) per field

and survey day since day of placement at the fields

(dashed horizontal reference line indicates initial colony weight)

Swedish oilseed rape (canola) study

16 plots of 5? hectares each Rundlof et al. Nature 521:77-80 2015

Clothianidin seed treated canola

Honey bees = no significant effects

Bumblebees = impacts on growth

Solitary bees = impacts

Colony size may hold the key?

Honey bee colonies have a buffer of adult bees

Challenges to Risk assessment

Need to protect all pollinators Are honey bees the best model? Means to test multiple lines of evidence

Courtesy of the Washington Post

Weight of Evidence

• Interpretation of field study within risk assessment will be made in the context of data drawn from lower Tiers

• Available data taken into account for consistency, coherence, and biological plausibility

• Available data may include: • Tier I laboratory acute/chronic toxicity

• Open literature

• Non-target arthropod data

• Sublethal effects

• Incident reports

• Tier II semi-field studies

• Tier III full field studies

• Exposure data

U.S. Environmental Protection Agency 32

Utility of Colony Simulation Models

• Understanding interdependent biological processes

• Interpret and relate sublethal measurement endpoints to assessment endpoints (e.g., colony strength and survival, quantity of hive products)

• Inform the design of higher tier studies

(e.g., timing, scale, replication, duration)

• Assist interpretation of Tier II and III study results

Account for observed variability in endpoints (e.g., season) Account for other non-chemical factors (e.g., weather)

• Incorporate data from multiple assessment Tiers

• Integrate chemical and non-chemical stressors

U.S. Environmental Protection Agency 33

Risk Management Decision Framework

Decision

Synthesis

Characterization

Analysis

Planning and Scoping

Legal Factors Public Values

Summary

• All pollinators are threatened, different life histories

• The honey bee superorganism is complex

Summary

• All pollinators are threatened, different life histories

• The honey bee superorganism is complex

• Test multiple pollinators and formulated product

• Realistic plots sizes are ideal but expensive

Summary

• All pollinators are threatened, different life histories

• The honey bee superorganism is complex

• Test multiple pollinators and formulated product

• Realistic plots sizes are ideal but expensive

• Modeling can identify gaps and synthesizes diverse data

Thank you for your attention

vanEngelsdorp, Pettis et. al (2009) JIP

Entombed pollen = high fungicide

workers bees recognized problem and

isolated the pollen with propolis

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Non-entombed Entombed

Pesticide Residue

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vanEngelsdorp, Pettis et. al (2009) JIP

Entombed pollen Control Entombed