# Colon y- level simula tion models **1** U.S. Environmental Pr otection Agency



## Ke ith Sappington, M.S. Environmental F ate and E ffects Division Office of P es ticide Pr ogr ams

# Outline

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## Po **te ntial utility of colon**  **y -**  **level simulation models f or**  **proposed risk assessmen**  **t fr amework** 

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## Curr **en t St**  **ate of the Science**  U.S. Environmental Pr otection Agency **2**



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## Discussion of select models

# Wh y co nsider co lon y simula tion models?

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### Understanding **in te**  **rdependent biological pr**  **ocesses**
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### In **te rpret**  **and r ela**  **te s**  **ublethal measurement endpoin**  **ts t o**  **assessmen t**  **endpoin ts**  (e.g., colon y s tr ength and surviv al, quantity of hiv e pr oducts) U.S. Environmental Pr otection Agency **3**



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### Inf**orm the design of higher tier s tudies**  (e.g., timing, scale, r eplication, dur ation)
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### Assis**t interpretati on**  **of Tier II and III s tudy results**  Account for observ ed va riability in endpoints (e. g., season) Account for other non - chemical fa ct or s (e.g., weather)
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### Incorpor**ate d**  **ata f**  **rom multiple assessmen**  **t Tier**  **s**
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### In **te gr** **ate c**  **hemical and non -**  **chemical stressors** 

# Curren t St ateo f the Science
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## SET **AC Pe**  **llston 1**  

## Conclusion (Ex**ecutive Summary):** “ None of the e

xis ting honey bee models seems suitable for regulatory risk assessment because...” (p 37)  

### Lack of link ag e between fo ra ge rs and surr ounding landsc ape  

### Most are insufficiently tested with empiric al data U.S. Environmental Pr otection Agency **4**



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### Most are insufficiently tested with empiric al data  

### Most lack sensitivity analysis t o under sta nd c on tr olling fact or s  

### Multiple stressor s are not included  

### Insufficient documentation with some models

1 Fischer , D . and T . Moriarty. 2011. Pesticide risk assessment for pollinators: summary of a SET AC Pellston W

orkshop . Edited by D . Fischer and T

. Moriarty. SET

AC Press. http://www .setac.org /s ites/default/files/ex ecutivesummarypollinators_20sep2011.pdf

# Attribut es of Select Models U.S. Environmental Pr otection Agency **5 Model**  **Scale Ke**  **y Model Output Ke**  **y Model**  **Inputs and**  **Pr ocesses**  Becher et al. 2010 Colon y Colon y siz e and composition Impact of **comb t emper** **ature** on egg la ying, brood development, colon y strength DeGr andi Hoffman et al. 1989 (BeeP oP) Colon y C olon y siz e and composition Impact of initial colon y siz e, **weather ,**  **photoperiod** , **queen fertility**  on brood development, colon y dynamics Khoury et al. Colon y Colon y siz e and composition Impact of **for ag**  **er death r ate**  on 2011 Colon y Colon y siz e and composition Impact of **for ag**  **er death r ate**  on onset of for aging; **task division** , brood and fo ra ger surviv al Makela et al . 1993 (AHBsim) Colon y and

population Colon y siz e and spatial

distribution of Africaniz ed and European honey bees Fo od quantity , task division, queen fe rtility , brood development, **swarming ,**  **migr ation,**  **genotype** Schmickl & Cr ailsheim 2007 HoP oMo ) Colon y Colon y siz e and composition, amount of pollen and honey Fo od quantity &processing, task division, queen fe rtility

, brood development, **for aging,**  **larv al**  **cannibalism** Thompson et al . 2005 Colon y Colon y siz e and composition **Pesticide impacts**  on egg la ying, brood rearing, onset of for aging, worker longevity

, colon y strength

# Attribut es of Select Models U.S. Environmental Pr otection Agency **6 Model**  **Spatially**

**Explicit? Sensitivity** 

**analysis? Model**  **Ve rification**  **Applica tion**  **to Pe**  **sticides?** Becher et al. 2010 No No Timing of peak hive str ength, minimum hive strength for overwintering No DeGr andi - Hoffman et al. 1989 (BeeP oP) Ye s* Ye s Limit ed comparison to liter ature studies Ye s ( We b ver sion) Khoury et al. 2011 No Limit ed Onset of for aging , for ager No age No Makela et al . 1993 Ye s No None No Schmickl & Cr ailsheim 2007 (HoP oMo) Ye s* Limit ed Select ed model components and output compar ed to liter ature data No Thompson et al . 2005 No No Limit ed comparison to colon y - level to xicity studies Ye s * Based on geographic differences in weather conditions

# Desired Fe at ures of a Colon y- level Simula tion Model • 

### Accoun **t fo**  **r major**  **fa ct**  **ors tha**  **t determine**  **colon y dynamics**  • 

### intr a - colon y and ev entually , inter - colon y • 

### Quan **tit atively**  **link v arious measur**  **emen t**  **endpoin ts**  **to assessmen**  **t endpoin**  **ts** • colon y strength & colon y surviv al, pr oduction of hive pr oducts 

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### Re **adily par ameteriz**  **ed, using e**  **xisting biological and pesticide**   U.S. Environmental Pr otection Agency ** 7**



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### Re **adily par ameteriz**  **ed, using e**  **xisting biological and pesticide**   ** specific da** **ta** • 

### Adapt **able to** **pes ticide uses tha**  **t diff** **er acr oss r**  **egions** • Account for geogr aphic variation in use pat te rn, cr ops, climat e, landscape 

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### Scien **tifically def ensible, tr** **ansparent, well documen**  **te d,**  **publically a va**  **ilable** 1 • Sensitivity and uncert ainty analysis • Eva luation relative to empirical data 1 Guidelines for environmental model development ha ve been published by the USEP A Council on R egulatory Environmental Models (C REM ) http://www .epa.gov/crem/index.html. Guidelines for “Mechanistic E ffects Models” are under development as part of an European Co mmission CREAM project (http://cream - itn.eu/ )

# Summary

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### Current colon y - level simulation models do not appear ready for regulatory use • 

### Once fully developed and ev aluated, colon y level models ha ve pot en tial t o serv e as an import an t line of evidence as part of risk char act eriz ation • 

### They ma y also be use ful for pr oblem formulation, designing and U.S. Environmental Pr otection Agency **8**



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### They ma y also be use ful for pr oblem formulation, designing and in te rpreting empiric al studies, and in te gr ating data gener ated at multiple risk assessmen t tier s • 

### EP A is in te rested in SAP feedback on the co ncept of using c olon y level models in pesticide ec ologic al risk assessmen ts and their current state of the science. (Charg e Question 14a&b) • 

### EP A seek s S AP c ommen ts on critic al model elemen ts that should be co nsidered in a honey bee c olon y - level model for use in pesticide ec ologic al risk assessmen ts. (Char ge Question 14c)