Imidacloprid effects on bees

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Imidacloprid is a nicotine-based systemic insecticide, belonging to a group of pesticides called neonicotinoids. Although it is off patent, the primary producer of imidacloprid is the German chemical firm Bayer CropScience. The trade names for imidacloprid include Gaucho, Admire, Merit, Advantage, Confidor, Provado, and Winner.

Imidacloprid acts as a neurotoxin and works by interfering with the transmission of nerve impulses in insects by binding to specific nicotinic acetylcholine receptors.[1] [2] [3]

As a systemic pesticide, imidacloprid translocates or moves readily in the xylem of plants from the soil into the leaves, fruit, flowers, pollen, nectar, and guttation fluid of plants. Bees may be exposed to imidacloprid when they feed on the nectar, pollen, and guttation fluid of imidacloprid-treated plants. [4] Based on its high water solubility (0.5-0.6 g/L) and persistence, both the U.S. Environmental Protection Agency and the Pest Management Regulatory Agency in Canada consider imidacloprid to have a high potential to run off into surface water and to leach into ground water. [5] [6] Long-term soil dissipation studies in apple orchards and with seed-treated barley crops showed accumulation of imidacloprid residues in soil with repeated applications. [7] [8]

Contents

[edit] History

Imidacloprid was first registered in the United Kingdom in 1993 and in the United States and France in 1994.[9] In the mid to late 1990s, French beekeepers reported a significant loss of bees, which they attributed to the use of imidacloprid. In 1999, the French Minister of Agriculture suspended the use of imidacloprid on sunflower seeds and appointed a team of expert scientists to examine the impact of imidacloprid on bees. In 2003, the panel of expert scientists called the Comite Scientific et Technique issued a 108-page report, which concluded that imidacloprid poses a significant risk to bees.[10] In 2004, the French Minister of Agriculture suspended the use of imidacloprid as a seed treatment for maize (corn).

In 2006, U.S. commercial beekeepers reported sharp declines in their honey bee colonies. Unlike previous losses, adult bees were abandoning their hives. Scientists named this phenomenon colony collapse disorder (CCD). Reports show that beekeepers in most states have been affected by CCD. [11] Although no single factor has been identified as causing CCD, the United States Department of Agriculture (USDA) in their progress report on CCD stated that CCD may be "a syndrome caused by many different factors, working in combination or synergistically." [12]

[edit] Toxicity of imidacloprid to bees

[edit] Acute

On an acute basis, the median lethal dose (LD50) to kill 50% of the population of adult honeybees is 0.078 micrograms active ingredient/bee (μg a.i./bee) for contact toxicity and 0.0038 μg a.i./bee for oral ingestion. Other insecticides that are equally or more toxic than imidacloprid include Spinosad, emamectin benzoate, Clothianidin, Fipronil, Thiamethoxam, and Dinotefuran.[13]

[edit] Sublethal

The majority of studies that measure toxicity of pesticides to bees focus on estimating the lethal dose (LD50) in acute toxicity tests to adult honeybees. This is only a partial measure of the harmful effects that pesticides can have on bees. For a complete analysis of the impact of pesticides to bees, sublethal effects should be considered.

Dozens of research articles have been published in peer-reviewed journals, which show sublethal effects to adult bees exposed to low levels of imidacloprid. In these studies, sub-lethal doses of 1-24 ug/kg and 0.1 - 20 ng/bee have been shown to impair navigation, foraging behavior, feeding behavior, and olfactory learning performance in honeybees (Apis mellifera).[14][15][16][17][18][19][20] Other studies examining higher levels of imidacloprid (50 - 500 ppb) also found that imidacloprid decreases foraging activity and affects bee mobility and communication capacity.[21][22][23]

[edit] Chronic

In 10-day chronic feeding studies with honeybees (Apis mellifera), 50% mortality was reached at levels between 0.1 and 10 ug/kg imidacloprid.[24] Other chronic toxicity studies conducted by Moncharmont et al. (2003) and Decourtye et al. (1999) have demonstrated chronic NOAEC values of <4 ppb and 4 ppb, respectively in honeybees.[25][26] In bumble bees, Mommaerts et al. (2009) demonstrated a LOAEC of 10 ppb for imidacloprid.[27]

Many tunnel and field studies have been conducted to show the potential effects of imidacloprid in the natural environment. Unfortunately, most of these field studies have design and implementation deficiencies, which make them difficult to interpret and use.[28][29]

[edit] Synergistic effects

Two research teams led by Jeff Pettis at the U.S. Department of Agriculture and Cedric Alaux at INRA/France have demonstrated that interactions between the pathogen Nosema and a neonicotinoid imidacloprid significantly weaken the immune systems of honeybees (Apis mellifera). In their research, Alaux et al. (2010) found that bees infected with Nosema and exposed to 0.7 ug/kg imidacloprid had an increased rate of mortality compared to the controls. The combination of Nosema and imidacloprid also significantly decreased the activity of glucose oxidase, an important enzyme that allows the bees to sterilize their colony and brood food. Without this enzyme, bees can become more susceptible to infections by pathogens. Both the USDA study and the INRA study demonstrate that a combination of stressors (pesticides and pathogens) may be responsible for the recent high level of bee losses.[30][31]

In 2012, researchers announced findings that sublethal exposure to imidacloprid rendered honey bees significantly more susceptible to infection by the fungus Nosema, thereby suggesting a potential link to CCD. [32]

[edit] Other studies

Bayer CropScience studies show that the maximum dose of imidacloprid for which no adverse effects were observed in bees is 20 ppb. Since Bayer claims that residue levels are usually below 5 ppb in pollen and nectar, they contend that imidacloprid poses a negligible risk to bees. [33]

Gerard Eyries, marketing manager for Bayer's agricultural division in France, states that studies confirm that imidacloprid leaves a small residue in nectar and pollen, but there is no evidence of a link with the drop in France's bee population, adding, "It is impossible to have zero residue. What is important is to know whether the very tiny quantities which have been found have a negative effect on bees." He also added that the product was sold in 70 countries with no reported side effects. [34]

Other independent studies have indicated that imidacloprid residues in plants can be higher:[35][36][37] [38]

  • 10 to 20 ppb in upper leaves
  • 100 to 200 ppb in other leaves
  • 1.5 ppb in nectar
  • 2 to 70 ppb in pollen

[edit] Uncertainties

It is important to note that the majority of studies conducted on pollinators have been performed in adult honeybees (Apis mellifera). Very few studies have been conducted on wild bees, most of which are solitary and raise their young in burrows and small colonies. There are also few studies that have been conducted on brood, larvae, or the queen, making it difficult to determine the impact of pesticides on different members of the colony and life stages of the bee. Although a number of field and semi-field studies have been conducted on imidacloprid and bees, these studies have design and implementation deficiencies, which make them unusable. Thus, the chronic effects of imidacloprid in the field is still unknown. [39]

[edit] Events in the decline of bees

[edit] 2001

In 2001, Bayer CropScience brought a judicial case against Maurice Mary, one of the leaders of the French Association of Beekeepers for disparagement of the chemical imidacloprid. The action was dismissed by the court in May 2003.

[edit] 2002

A similar battle occurred in Nova Scotia, where beekeepers believed that imidacloprid used on potatoes resulted in massive losses of bees, which are needed for blueberry pollination.

[edit] 2003

In 2003, French Agricultural Minister Jean Glavany again extended the suspension of the use of imidacloprid on sunflower seeds. In spite of a four-year ban on sunflower seed treatment, a significant drop in bee losses was not observed. Beekeepers were cited as saying the measure was insufficient since residue studies found that imidacloprid accumulates in soil and leaves a residue. Even after five years, plants sowed on the same spot as the crop could contain traces of the product. [40]

Some also pointed out that bee colony losses could also be due to the use of imidacloprid on other crops such as corn, or from the replacement of imidacloprid by another systemic insecticide called fipronil. Fipronil is as toxic to honeybees on an acute oral basis as imidacloprid. Indeed in May 2003, the DGAL (Direction Générale de l'Alimentation du ministère de l'Agriculture ) indicated death of bees observed in the south of the country had been caused by acute toxicity by fipronil (trade name Regent). Not until beekeepers stopped using imidacloprid and fipronil did the bee population rebound in France. [41]

[edit] 2008

In June 2008, the German Federal Office of Consumer Protection and Food Safety suspended the registration of eight neonicotinoid pesticide seed treatment products used in oilseed rape and sweetcorn, a few weeks after honeybee keepers in the southern state of Baden Württemberg reported a wave of honeybee deaths linked to one of the pesticides, clothianidin.[42]

In August 2008, the Coalition against Bayer Dangers (CBG) brought a legal case against Werner Wenning, Bayer's chairman, for marketing dangerous pesticides (neonicotinoids), which are causing the death of bees worldwide.[43]

[edit] 2010

In November 2010, an EPA document was released, detailing the risks to honeybees from exposure to clothianidin, a neonicotinoid similar to imidacloprid. The EPA document states: "This compound is toxic to honey bees. The persistence of residues and potential residual toxicity of clothianidin in nectar and pollen suggests the possibility of chronic toxic risk to honey bee larvae and the eventual instability of the hive."[44]

[edit] 2011

In January 2011, an online petition to save the bees was launched by Avaaz.org to push the United States and European Union to join the ban of the neonicotinoid pesticides.[45]

[edit] Media portrayal

In October 2009, a documentary film, Vanishing of the Bees, was released in theatres in the UK. The film interviewed a number of experts in connection with CCD and suggested a link does exist between neonicotinoid pesticides and CCD. However, the experts interviewed conceded no firm scientific data yet exist. Industry-sponsored studies appear to be inconsistent with those produced by independent scientists. Even after 18 years of use, regulatory agencies still do not have conclusive data to determine the effects of imidacloprid on bee colonies. [46][47]

In February 2010, the documentary film Nicotine Bees was released. This film analyzes the possible factors contributing to the large bee die-offs worldwide and concludes that the large use of neonicotinoids is the most probable cause of the recent bee die-offs.[48]

[edit] See also

[edit] References

  1. ^ [1]
  2. ^ [2]
  3. ^ [http://npic.orst.edu/factsheets/imidagen.pdf
  4. ^ [3]
  5. ^ [4] Environmental Fate and Effects Division Problem Formulation for Imidacloprid
  6. ^ [5] Canadian Water Quality Guidelines: Imidacloprid
  7. ^ [6] Canadian Water Quality Guidelines: Imidacloprid
  8. ^ [European Draft Assessment Report: Imidacloprid. Annex B, B.7. February 2006]
  9. ^ Pesticide Action Network. Imidacloprid
  10. ^ French Scientific and Technical Committee Final Report
  11. ^ [7] Congressional Research Service Honey Bee Colony Collapse Disorder
  12. ^ [http://www.ars.usda.gov/is/br/ccd/ccdprogressreport2010.pdf USDA Colony Collapse Disorder Progress Report. June 2010
  13. ^ EPA's Environmental Fate and Effects Division Problem Formulation for the Registration Review of Imidacloprid
  14. ^ [Armengaud, C., Lambin, M., Gauthier, M. 2002. Effects of imidacloprid on the neural processes of memory. In J. Devillers and M.H. Pham-Delegue, (eds). Honey bees: estimating the environmental impact of chemicals (pp. 85-100). New York: Taylor & Francis]
  15. ^ [Suchail, S., Guez, D.,and Belzunces, L.P.. 2001. Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis mellifera. Environ. Toxicol. Chem. 20: 2482–2486]
  16. ^ [Decourtye, A, Lacassie, E, Pham-Delegue, M-H (2003) Learning performances of honeybees (Apis mellifera L) are differentially affected by imidacloprid according to the season. Pest Manage Sci 59:269–278]
  17. ^ [Decourtye, A., Armengaud, C., Devillers, R.M., Cluzeau, S. 2004. Imidacloprid impairs memory and brain metabolism in the honeybee (Apis mellifera L.). Pesticide Biochem Phys. 78:83-92]
  18. ^ [Guez, D., Suchail, S., Gauthier, M., Maleszka, R., Belzunces, L. 2001. Contrasting effects of imidacloprid on habituation in 7- and 8-day old honeybees (Apis mellifera). Neurobiol Learning Memory 76:183-191]
  19. ^ [Pham-Delegue, M.H., Cluzeau, S. 1999. Effets des produits phytosanitaires sur l’abeille; incidence du traitement des semences de tournesol par Gaucho sur les disparitions de butineuses. In Rapport final de synthese au Ministere de l’Agriculture et de la Peche]
  20. ^ [Lambin, M., Armengaud, C., Ramond, S., Gauthier, M. 2001. Imidacloprid-induced facilitation of the proboscis extension reflex habituation in the honeybee. Arch Insect Biochem Physiol 48(3): 129-134]
  21. ^ [Medrzycki, P., Montanari, R., Bortolotti, L., Sabatini, A. G., Maini, S., Porrini, C. 2003. Effects of imidacloprid administered in sub-lethal doses on honey bee behaviour. Laboratory tests. Bulletin of Insectology 56 (1): 59-62]
  22. ^ [Yang, E.C., Chuang, Y.C., Chen, Y.L., Chang, L.H. 2008. Abnormal foraging behavior induced by sublethal dosage of imidacloprid in the honeybee (Hymenoptera: Apidae). J. Econ Entomology 101(6):1743-1748]
  23. ^ [Bortolotti L., Montanari R., Marcelino J., Medrzycki P., Maini S., Porrini C. 2003. Effects of sub-lethal imidacloprid doses on the homing rate and foraging activity of honey bees. Bulletin of Insectology 56(1): 63-67]
  24. ^ [Suchail, S., Guez, D.,and Belzunces, L.P.. 2001. Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis mellifera. Environ. Toxicol. Chem. 20: 2482–2486]
  25. ^ [Moncharmont, F.D., Decourtye, A., Hantier, C.H., Pons, O., Pham-Delegue, M. 2003. Statistical analysis of honeybee survival after chronic exposure to insecticides. Environ Toxicol Chem 22(12): 3088-94]
  26. ^ [Decourtye, A. Metayer, M. Pottiau, H., Tisseur, M., Odoux, J.F., Pham-Delegue, M.H. 1999. Impairment of olfactory learning performances in the honeybee after long-term ingestion of imidacloprid. In Hazards of Pesticides to Bees. INRA, Paris]
  27. ^ [Mommaerts, V., Reynders, S., Boulet, J., Besard, L., Sterk, G., Smagghe, G. 2009. Risk assessment for side-effects of neonicotinoids against bumblebees with and without impairing foraging behavior. Ecotoxicology 19:207-215]
  28. ^ French Scientific and Technical Committee Final Report
  29. ^ EPA's Environmental Fate and Effects Division Problem Formulation for the Registration Review of Imidacloprid
  30. ^ [Alaux, C., Brunet, J-L, Dussaubat, C., Mondet, F., Tchamitchan, S., Cousin, M., Brillard, J., Baldy, A., Belzunces, L.P., La Conte, Y. 2010. Interactions between Nosema microspores and a neonicotinoid weaken honeybees (Apis mellifera). Environmental Microbiology 12(3): 774-782]
  31. ^ Pettis, J. 2009. Status of Pollinator Health. USDA-ARS Bee Research Lab, Beltsville, MD
  32. ^ cite journal|author = Pettis, S., Dennis vanEngelsdorp, Josephine Johnson and Galen Dively|year = 2012|title = Pesticide exposure in honey bees results in increased levels of the gut pathogen Nosema|journal = Naturwissenschaften|volume = 99|issue = 2|pages = 153-158|doi = 10.1007/s00114-011-0881-1}}
  33. ^ [8]
  34. ^ [9]
  35. ^ [Bonmatin, J.M., Marchand, P.A., Charvet, R., Moineau, I., Bengsch, E.R., and Colin, M.A. 2005. Quantification of imidacloprid uptake in maize crops. J. Agric. Food Chem. 53: 5336-5341]
  36. ^ [10]
  37. ^ [Laurent, F.M. and Rathahao, E. 2003. Distribution of 14C-imidacloprid in sunflowers (Helianthus annuus L.) following seed treatment. J Agric Food Chem 51(27): 8005-10]
  38. ^ [11]
  39. ^ [12] Environmental Fate and Effects Division Problem Formulation for Imidacloprid
  40. ^ [European Draft Assessment Report: Imidacloprid. Annex B, B.7. February 2006]
  41. ^ [http://pcela.rs/interview_henryEn.htm
  42. ^ "Emergency Pesticide Ban for Saving the Honeybee" Institute of Science in Society, 2008
  43. ^ CBG Germany: Charge against Bayer´s Board of Management August 25, 2008
  44. ^ Memorandum US EPA Office of Chemical Safety and Pollution Prevention; November 2, 2010
  45. ^ Avaaz.org petition
  46. ^ Official website of the 2009 documentary Vanishing of the Bees
  47. ^ French Scientific and Technical Final Report
  48. ^ Nicotine Bees website

[edit] External links

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