Introduction
Colony Collapse Disorder (CCD), also known as Colony Bee Depopulation Syndrome (HBDS), is a situation where worker bees suddenly disappear from beehives. Such disappearances have taken place from historical times. However, in 2006, there were massive disappearances of Western honeybee colonies in parts of North America; a situation that led to coining of the word colony collapse disorder (Penn State/College of Agricultural Sciences, 2007). Similar disappearances were reported across Europe in countries like Spain, Portugal, Greece, Italy, Netherlands, France and Belgium. Beekeepers reported over 90% of bee loss in their hives. Even though bee loss during winter is common, this margin was beyond the anticipated limits. Researchers have put forward several postulates to explain this phenomenon including biotic factors, environmental related strains, pesticides and malnutrition (Sahba, 2007). Despite the many models put forward to explain these phenomena, this paper analyses the toxicological view of CCD.
Background Information
There are several chemicals thought to cause CCD. These chemicals have different effects on bees and thus fall in different categories. According to Penn state/College of Agricultural Sciences (2007), contact insecticides kill bees upon contact and this affects mainly the worker bees due to spraying. Systemic chemicals contaminate the nectar and pollen after incorporation into the treated plants. This kills bees even in hives. Finally, the more hazardous pesticides are dust pesticides. Intense bee poisoning occurs during the blooming period as farmers apply insecticides to crops (Mayer, Johansen & Baird, 1999, p. 2). Poisoning also occurs as toxic pesticides drift onto bordering weeds and crops when they are blooming. Another interesting poisoning phenomenon occurs when insecticidal dust clings to scrounging bees becoming packed together pollen. This is very dangerous because the insecticidal dust may kill newly formed workers in subsequent seasons. This paper will deal with the common pesticides that are currently under research. They include antibiotics, miticides and neonicotinoid pesticides.
Analysis of Key Potential Causes of CCD
According to CCD Steering Committee (2009), fluvalinate and coumaphos, which are both miticides, chlorpyrifos, fungicides and herbicides, are the major toxicological contaminants identified in the undergoing CCD research (p. 8). The Agricultural marketing Service (AMS) carried out a study that indicated that, miticides used commonly by beekeeper, could be a possible cause of HBDS (CCD Steering Committee, 2009, p. 8). Unfortunately, research has not determined precisely any single cause of CCD. However, this continuing research offers some insights into what may be behind this disappearance. Due to established weakness of honeybees regarding detoxification, pesticides become the chief suspect as a causal effect of CCD. Honeybees have low levels of detoxification probably due to their habit of feeding on pollen and nectar that have low poisonous content (Johnson, 2008, p. 6).
CCD Steering Committee (2009) posits that, scientific research indicates a synergistic mode of operation between these chemicals (p. 8). Research indicates that combination of fluvalinate and coumaphos increases toxicity levels. Scientists link these two miticides to suppressed immune system and increased pathogen levels in honeybee colonies; a factor that contributes to poor health within colonies hence increased CCD (CCD Steering Committee, 2009, p. 8). Other naturally occurring chemicals were also found to be potential causes of CCD. Scientists isolated hydroxymethylfurfural (HMF) from fructose syrup and this linked strongly to increased instances of CCD where poor health characterizes the situation (CCD Steering Committee, 2009, p. 9).
The other toxic chemical that may be behind CCD is antibiotics. According to Suszkiw (2005), Agricultural Research Service (ARS) developed antibiotic tylosin tartrate, to counter the effects of American foulbrood disease. It is important to note at this point that, this antibiotic came into market in October 2005, one year before CCD set in (Suszkiw, 2005). American foulbrood is a bacterial disease caused by Paenibacillus larvae and it kills young larvae. Researchers associate this chemical with CCD because, CCD started almost around the same time when this antibiotic entered the market. As noted earlier CCD Steering Committee reported that, there is no conclusive information about what causes CCD and research work is underway to elaborate on the issue. Another antibiotic linked to HBDS is Terramycin and may work in concert with other antibiotics to cause CCD.
Neonicotinoids come third in this series of toxic chemicals that cause CCD. According to Johnson (2008), these pesticides are derived from nicotine and are commonly used in most gardens (p. 8). This is a systemic chemical and it works internally. Imidacloprid is the common neonicotinoid. Johnson (2008) posits that, nicotine is a very good insecticide but also toxic to mammals (p. 8). To reduce this toxicity in mammals, scientists altered the structure of nicotine and it worked resulting to reduced mammal toxicity. However, as the toxicity to mammals decreased, toxicity to bees took the opposite direction (Johnson, 2008, p. 8). Even though imidacloprid does not kill bees, it may cause a behavioral change that may in turn cause massive disappearance of bees. It is difficult to tell how bees are learning to change behavior and migrate from one hive to another.
Conclusion
Across Europe, beekeepers are feeling the pinch of CCD. Such outbreaks have been reported in the past popularly known as disappearing disease, spring dwindle, October disease among other names. However, the disappearance that started back in the winter of 2006 has caused great concerns. Actually, this outbreak resulted to coining of the word ‘Colony Collapse Disorder.’ Researchers have put forward different hypotheses to address the cause of CCD in the last few years. Unfortunately, there is no precise information that points clearly to the cause CCD. Presently there are only suggestions ranging from changing environmental conditions through viruses to toxic chemicals among other postulations.
Toxic chemicals come first among the postulated causes of CCD. This is primarily because farmers are increasingly using chemicals to protect their plants from pests. Bees then collect nectar from these plants and consequently encounter these poisonous compounds. There are numerous chemicals thought to be behind CCD. However, researchers have singled out three prime suspect chemicals associated with this disappearance. They include antibiotics, miticides and neonicotinoid pesticides. The reason why antibiotics lie in this category is that, in 2005, ARS released tylosin tartrate into the market. The following year CCD set in thus offering a strong correlation between the two. Miticides are known to suppress the immune system leading to poor health and disappearance occurs as a consequence (CCD Steering Committee, 2009). On the other hand, use of neonicotinoid, a new nicotine derivative relates strongly to CCD. In a bid to reduce toxicity of nicotine in mammals, chemists altered its structure and formed neonicotinoids in lieu. These substances are unfriendly to bees and most probably cause CCD.
Therefore, the potential toxicological causes of CCD, according to the writer may be antibiotics and neonicotinoids. However, the writer feels that these chemicals may work synergistically to produce results that are more devastating.
References
CCD Steering Committee. (2009). Colony Collapse Disorder Progress Report. Web.
Johnson, R. (2008). Experiencing BeeSpace: Colony Collapse Disorder. Web.
Mayer, D., Johansen, C., & Baird, C. (1999). How to Reduce Bee Poisoning from Pesticides. Web.
Penn State/College of Agricultural Sciences. (2007). Honey Bee Die-off Alarms Beekeepers, Crop Growers and Researchers. Web.
Sahba, A. (2007). The Mysterious Deaths of the Honeybees. CNNMoney.com. Web.
Suszkiw, J. (2005). New Antibiotic Approved for Treating Bacterial Honey Bee Disease. Agricultural Research Service. Web.