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Goals and Objective: Goal 1
Objective 1.6

Obj 1.6: Elucidate the synergistic and sub-lethal effects of in-hive miticides on colony health

(M. Ellis)

Rationale and significance
There is need to test miticides used by beekeepers for synergistic interactions and to establish synergistic ratios by conducting bioassays for various miticide combinations. CSREES has recently funded two collaborators in this CAP to study sub-lethal effects of pesticides. This objective avoids redundancy and fills knowledge voids by:

  1. deriving new basic toxicology (LD50s) on all active ingredients currently registered for Varroa,
  2. focusing on understudied synergies of in-hive pesticides, and
  3. providing sub-lethal response data for reproductive drones and queens.

Currently, 8 miticides are registered for Varroa suppression in North America. Significant quantities of coumaphos and fluvalinate have been found in wax, propolis and other hive products (Bogdanov et al. 1998a,b, Lodesani et al. 1992, Wallner 1995). Fluvalinate and coumaphos are highly persistent in the hive with an estimated half-life in beeswax of 5 years (Bogdanov 2004). When beekeepers rotate treatments, honey bees are exposed to varying ratios of two or more chemicals. While the bee toxicity of individual materials has been determined for some miticides (Aliano and Ellis 2007, Ellis and Baxendale 1997, Macedo et al. 2002), they have not been evaluated for synergistic interactions (Ellis et al. 1997).

With the exception of coumaphos and fluvalinate (Collins et al. 2004, Haarman et al. 2002, Rinderer et al. 1999), miticides have not been examined for sub-lethal effects on drones and queens (Desneux et al. 2007, Belzunces et al. 1993). In addition to causing acute mortality and sub-lethal effects, exposure to toxic chemicals can weaken the immune system. One telling condition of colonies suffering from CCD is an abundance of micro-organisms in their bodies not found in healthy bees (Cox-Foster 2007).

Expected outcomes
To determine:

  1. LD50s for honey bee workers for the 8 miticides used by beekeepers to control Varroa,
  2. synergistic ratio for each pair of miticide combinations,
  3. the impact on sperm viability of the 8 miticides,
  4. time to death for queens treated with sub-lethal doses and interacting combinations.

Pesticide sub-objectives

  • 1.6. Elucidate synergistic and sub-lethal effects of in-hive miticides on colony health
  • 1.7. Determine sub-lethal effects of pesticide metabolites on physiological and behavioral systems
  • 1.8. Determine sub-lethal effects of pesticides on bees exposed to pesticides and selected combinations of pesticides during larval development and the nurse bee stage

Workers across these objectives are aware of the need to coordinate with fellows in Objective 1.2E to provide optimum pesticides and dosages for studies on interactions of pathogens with toxins.


Summary Statement for Goal 1
This goal constitutes our attempts at understanding the most important morbidity factors at work in North American Apis mellifera. Work in this Goal is characterized by a high degree of interinstitutional linkages within CAP labs, resulting in four topical groups. The Nosema group is comprised of Lee Solter (Univ IL), Tom Webster (KY State Univ), Zach Huang (MI State), Christina Grozinger (Penn State), and Kate Aronstein (ARS Weslaco). The virus group is made up of Jay Evans and Judy Chen (ARS Beltsville) and Lee Solter. There have been cross-group linkages with Greg Hunt (Purdue) who is studying the genetic basis of bee resistance to N. ceranae and Israeli Acute Paralysis Virus (IAPV). A diagnostics group is comprised of Jay Evans, Judy Chen, and Kate Aronstein. The toxicology group is comprised of Marion Ellis (Univ NB), Maryann Frazier, Jim Frazier, and Chris Mullin (Penn State). A sentinel apiary monitoring group, led by Frank Drummond (Univ. of Maine), is comprised of Nancy Ostiguy (Penn State), Marla Spivak (Univ. of Minn.), Kate Aronstein (ARS Weslaco), Sheppard (Univ. of Wash.), Kirk Visscher (Univ. of CA - Riverside); analytic work by Anne Averill (Univ. of Mass.), Nancy Ostiguy (Penn State), and Brian Eitzer (CT Experiment Station) is collecting baseline data on field colonies and factors contributing to bee morbidity. And finally, an IPM adoption group is headed up by Keith Delaplane (Univ GA).


Methodology, data and analysis of results to date are shared in an annual report to USDA. Papers generated by team members during the time of the CAP are listed and periodically updated below. Beyond the citation of published papers, the consensus of the group is that it would otherwise be unhelpful or possibly misleading to state preliminary results within the context on this web site.


Publications of objective 1.6 principal investigator (M. Ellis) to date during the CAP

Ellis, M.D. Pesticides Applied to Crops and Honey Bee Toxicity. 2010. American Bee
Journal, 149(5):485-486

Ellis, M.D., B. Teeters. 2011. Assessing the Risks of Honey Bee Exposure to Pesticides. American Bee Journal, 151(7):682-683.

Heintz, C, M. Ribotto, M. Ellis, K.S. Delaplane. 2011. Best Management Practices (BMPs) For Beekeepers Pollinating California’s Agricultural Crops. American Bee Journal, 151(3):265-268

Johnson, R.M. , M. Ellis, C.A. Mullin , M. Frazier. 2010. Pesticides and honey bee toxicity - USA. Apidologie 41:312–331 DOI: 10.1051/apido/2010018

Johnson, R.M., M.D. Ellis, C.A. Mullin, M. Frazier. (ed. Samataro) Book: ”Honey Bee Colony Health: Challenges and Sustainable solutions” Book chapter 14, Pesticides and Bee Toxicity - U.S.A Taylor and Francis, LLC, (accepted, 2011)

Yves Le Conte, M. Ellis, W. Ritter. 2010. Varroa mites and honey bee health: can Varroa explain part of the colony losses? Apidologie, DOI: 10.1051/apido/2010017

Further Background Information
Documentation of CAP progress in general, and of this objective in particular, is available through the following sources:

  1. Bee Health, an eXention initiative for peer-reviewed scientific recommendations
  2. Colony Collapse Disorder Progress Report for 2009
  3. When Varroacides Interact
  4. Pesticides Applied to Crops and Honey Bee Toxicity
  5. Wild Bee Status and Evidence for Pathogen 'Spillover' with Honey Bees
  6. Assessing the Risks of Honey Bee Exposure to Pesticides
  7. Pesticides and their involvement in Colony Collapse Disorder
Updated August 19, 2011.