Running head: BEE EXTINCTION
The Reasons Behind the Massive Extinction of Bees
Xhulia Tafa
Composition 1, Michelle Pani
14.06.2018
BEE EXTINCTION
Abstract
Recently the population of bees is decreasing in a rapid way. Many scientists and biologist
are investigating the reasons of this massive disappearance of bees. There are lots of factors
which are harming and killing many of bees each year. Bee diseases and parasites, the use of
pesticides, the habitat deterioration and climate change are the main causes of the
disappearance of bees. The aim of this study is to explain how each of these factors possess a
dangerous threat for the life of thousands bees. Many journal articles, publications by
different universities and organization have published about the bee's extinction. Each study
examines the damages that diseases, pesticides and humans cause to bees.
Keywords: bees, extinction, parasites, diseases, chemicals, habitat loss, climate change,
people.
BEE EXTINCTION
Did you know that honey and beeswax have been used by people since antiquity? The
ancient Egyptians were aware of the importance of bees and learned how to benefit from
them. Honey and beeswax were utilized in food, medicine, and in the embalming process
(Davis, 2014). Since then, people have been benefiting from bees and their products, without
taking in consideration bees’ condition. Many individuals were so focused in profiting from
bees, that they forgot to take care of bees’ health and needs. Nowadays, bees’ populations
have started to decrease in a rapid way, because of human greed and carelessness. Even
though bees are known for their crucial contribution to the ecosystem and humankind, they
are still underestimated. Many scientists and organizations are trying to understand the
reasons behind the massive disappearance of thousands bees. Bees are going to extinct due to
bee diseases and parasites, use of pesticides, habitat deterioration and climate change.
Just like other species, bees are not immune to various diseases. Many bees are
harmed or even killed by numerous parasites, pathogens, and bacteria. Parasitic mites are
famous for damaging and weakening bee colonies. They are large in number and cause
different symptoms. The most famous parasitic mites are Acarapis woodi, Tropilaelaps
clareae, and Varroa jacobsoni. Researchers Yves Le Conte and Maria Navajas (2008) in their
analytic study “Climate change: Impact on honey bee populations and diseases”, indicate
how these mites affects bees. According to them, Acarapis wood lodge themselves in the
esophagus of bees and eventually suffocate them. While Tropilaelaps clareae are defined as
brood parasites. These parasites depend on the bee brood very much, because they can die
after seven days without it. They reproduce very quickly, and stimulate the emergence of
other pathogens. Many bee colonies are killed due to the proliferation of these parasites.
Meanwhile, Le Conte and Navajas point out that Varroa jacobsoni is the most destructive
parasite, due to the fact that the majority of scientists attribute bee mortality to this parasite.
BEE EXTINCTION
All bees infected with these mites are predisposed to die, because Varroa mites weaken the
immune responses of bee. In addition, they encourage viral infections and transmit various
viruses and bacteria. For centuries, parasitic mites have been infecting thousands of bees,
causing many lethal diseases to bees.
Also, Le Conte and Navajas (2008) state that some bee diseases happen due to
protozoa pathogens. In this analytic study, they describe Nosema apis and Nosema cerana as
the most dangerous protozoa pathogens. Even though these pathogens resemble with each
other, they do not cause the same signs in bees. Nosema apis attacks the internal organs of
adult bees, eventually leading to their deaths. This disease is hard to be depicted, because it
can advance without detectable symptoms. Furthermore, Nosema apis can manifest itself
when the colony is weak. The disease is more likely to develop in long and wet winters,
because bees cannot go outside and drop their excretion inside the hive, contaminating other
bees. Afterwards, it is impossible to prevent the disease from spreading quickly. While,
Nosema cerana impacts the ability of bees to produce honey, abruptly leading in honey loss
(Le Conte & Navajas, 2008,).
Another major threat for bee population is the bacteria pathogenic, which attack the
brood. Bees suffer from many harmful brood diseases. American foulbrood is the most
widespread and the most destructive of brood diseases. This disease has been present for
centuries and has caused irreparable damages to bee colonies. One study from Mid-Atlantic
Apiculture Research and Extension Consortium (MAAREC, 2005) in collaboration with
various American universities, in their article “Bee diseases and their control’’ analyse the
consequences of these diseases on bees. According to MAAREC, American foulbrood
disease is caused by Bacillus larvae. This disease is very serious and contagious. If American
foulbrood advances rapidly, it can kill an entire colony in a season. Even in cases when the
disease may not develop to its critical stage, it will only lengthen the time of colony
BEE EXTINCTION
disappearance. What makes this disease even more destructive is the fact that it can be
transmitted easily from a colony to another. A colony infected by American foulbrood
becomes weak and incapable of protecting itself from the intrusion of bees coming from
nearby healthy colonies. These bees take back the infected honey to their own colony. As a
result, the healthy colonies get infected rapidly and the same process will be repeated again
(Bee Diseases and their Control, 2005).
Besides diseases and parasites, bees are also endangered because of the massive use
of pesticides. Nowadays, pesticides have a large usage in modern agriculture, as farmers use
them to protect crops, flowers, fruits, and other plants from insect pest, vermin and other
plant diseases. Researchers Desneux, Decourtye and Delpuech (2007) in their analytic study
“The Sublethal Effects of Pesticides on Beneficial Arthropods” define pesticides as toxic
chemicals which are meant to keep in control a group of organism by interfering with specific
metabolic pathways. Pesticides do not affect only the targeted group of organism, but also
other species with similar metabolism. The pesticide concentration can be sublethal or lethal
for species. Pesticides with a very high dose are fatal for all species, especially for bees.
Pesticides with a lower dose are considered as sublethal, because they do not kill organisms.
However, sublethal doses affect the normal functioning and health of organisms (Desneux,
Decourtye & Delpuech, 2007).
Recently, lots of people are against the use of pesticides, due to the harm that they
cause to different species, in particular to bees. In the chapter four of “Beekeeping and Bee
Conservation”, authors Francisco Sanchez-Bayol and Koichi Gota (2016) describe the impact
of pesticides on bees. According to them not only pesticides with lethal doses are harmful to
bees, but also those with sublethal doses. Exposure of bees to sublethal doses may interfere
with their psychological state, feeding behaviour and navigation process. Sanchez-Bayol and
Gota explain that pesticides, like fungicides and herbicides, may produce stress in bees.
BEE EXTINCTION
When bees try to metabolise and eliminate toxic chemicals, they use a large amount of
energy. This process causes psychological problems for bees, resulting in abnormal
behaviours of bees. In addition, the continuous applications of herbicides in crops and
forestry zones have affected the biodiversity of these areas. The lack of certain plants implies
less amount of pollen for bees. Therefore, bees have difficulties in collecting the proper
amount of pollen (Sanchez-Bayo1 & Goka, 2016).
A study by biologists at the University of California San Diego (2017) reveals that the
neonicotinoid pesticide can affect the ability of bees to fly. Biologists Tosi, Nieh and Burgio
created a flight mill, which is a bee flight-testing instrument made by scratch, to prove their
claim that this widely used pesticide impacts the flight ability of bees. For months, many bees
flew under continuous and controlled conditions. From this experiment, it is found out that
neonicotinoid exposure causes considerable damages to the bee's ability to fly. "Our results
provide the first demonstration that field-realistic exposure to this pesticide alone, in
otherwise healthy colonies, can alter the ability of bees to fly, specifically impairing flight
distance, duration and velocity" researchers state. According to them, long-term exposures to
this pesticide not only decrease the bee’s ability to fly, but also the possibilities of returning
home. "The honey bee is a highly social organism, so the behaviour of thousands of bees is
essential for the survival of the colony. We've shown that a sub-lethal dose may lead to a
lethal effect on the entire colony," they conclude (Tosi, Nieh & Burgio, 2017). All these
studies show that the use of pesticides reduces the survival chances for bees. Even when
pesticides do not kill bees immediately, they still cause irreplaceable damages to bees.
During the 21st century, the earth underwent through domestic changes. Most people
destroyed the natural habitat, causing landscape degradation and fragmentation. The loss of
habitat diversity impacts most of the species, especially pollinators. The destruction of the
natural habitat has negative effects on bee populations. Fragmentations of large habitats into
BEE EXTINCTION
small isolated areas reduce food sources for bees. When bees cannot find benefit from
various plants, their food is limited and reduced. As bees need to have an undisturbed habitat
so that they can nest, roost, and forage (Kluser, Neumann, Chauzat & Pettis, 2010). As a
result, the whole bee colony is at risk of extinction, due to food insufficiency. The Ecological
Society of America presents the conference “Saving Our Bees: Implications of Habitat Loss”
(2008), in which scientist from different disciplines explore the problem of bee habitat loss.
In this conference researcher Rachael Winfree presents a combination of more than fifty
publications regarding bee population sizes and diversity issues. Winfree shows that the
population of bees were smaller in areas with extreme fragmentation than in natural areas.
Another experiment made by doctor Neal Williams and his team explains that the further a
colony is from natural parts, the fewer worker bees it contains. William and his team discover
that bees have to travel several kilometres to find nectar and pollen, when in cases when the
crop fields aren't in bloom for the entire bee active season (Ecological Society of America,
2008). These studies demonstrate the damages that habitat deterioration causes to bees. Not
only the natural habitat of bees is destroyed, but also the food sources and the population of
bees is reduced. Thousands of bee colonies all over the world are suffering the consequences
of habitat loss.
One more factor that it is diminishing the population of bees is the climate change. Le
Conte and Navajas (2008) explain that bees’ behaviour is in harmony with weather
conditions. On rainy, cold days bees do not go out, while in hot days they gather water to
keep their colony cool. In some regions, winter is lasting longer due to climate change
impact. This phenomenon is negatively effecting the development cycle of bee. During
winter, bees consume their honey storages to survive until spring. According to Le Conte and
Navajas, when winter last longer that it was supposed to, bees have to find extra amount of
food so that they can have enough energy for survival. As mentioned earlier, they cannot go
BEE EXTINCTION
out, so they have to use the stored honey. The honey bee’s ability to manage energy reserves
exerts significant adaptive pressure. Bees are put under constant pressure and their
psychological state is worsened. Even though, sometimes bees are unable to handle this
situation and may die of starvation (Le Conte & Navajas, 2008).
Also, climate can alter the emerging time of different species. The constant rising of
temperatures is making flowers bloom earlier than expected. Many bees miss the opportunity
to pollinate flowers in time. Thus, temporal mismatches may happen between bees and plant
species. By the time that bees start to pollinate, the amount of available nectar is reduced and
rivalry for finding nectar becomes stronger. A team of researchers from the Department of
Animal Ecology and Tropical Biology of the Julius Maximilians University of Würzburg's
Biocenter (2017) make an experiment to show what happens to bees when temporal
mismatches occur. Doctor Schenk, one of the researchers, explains that even a three or six
days mismatch is enough to damage the bees. The majority of bees die without food plants
for three or six days. Even those bees who manage to survive have to reduce their
productivity output. Schenk finds out that some bees tried to produce more male offspring,
because they eat less amount of food than young females. However, Schenk says that this
method causes a decline in population. Even though bees are trying to cope with climate
change, there is no way they can escape from climate change’s consequences (JMU, 2017).
All in all, bees have to deal with various challenges, which are putting in risk their
existence on Earth. Day by day this situation is getting worse, causing a rapid decline in the
population of bees. People are aware that bees are in danger of going to extinct. Yet, nothing
seems to be done to prevent this phenomenon. One major reason for bee’s population decline
is bee diseases and parasites. Parasitic mites, protozoa pathogens and diseases like American
foulbrood are attacking, infecting and killing thousands of bees in a short time. Apart from
these diseases, human activities are the real major threat for bees. People are not helping
BEE EXTINCTION
bees, but taking advantage of them. The use of pesticides by farmers is affecting in a negative
way the physiological state, their feeding behaviour and orientation process of bees. In
addition, habitat deterioration and climate change are happening due to people’s carelessness.
Habitat loss reduces the natural habitat and food sources of bees. Meanwhile, climate change
changes the development cycle of bees and interferes with their pollination process. All these
factors attack bees and leave no chance of survival for them. It is a matter of time for bees to
go in complete extinction, if humans continue to ignore this situation. “Bees are reaching
their tipping point because they are expected to perform in an increasingly inhospitable
world” (Spivak, Mader & Vaughan, 2011).
BEE EXTINCTION
References
Davis, J. (2014). 10 Reasons Why Bees Matter | The Ecology Center. Retrieved from
https://www.theecologycenter.org/resources/10-reasons-why-bees-matter
Desneux, N., Decourtye, A., & Delpuech, J. (2007). The Sublethal Effects of Pesticides on
Beneficial Arthropods. Retrieved from
http://aulavirtual.agro.unlp.edu.ar/pluginfile.php/24998/mod_resource/content/1/suble
thaleffects_desneux_2007.pdf
Ecological Society of America. (2008, August 5). Saving Our Bees: Implications of Habitat
Loss. ScienceDaily. Retrieved May 23, 2018 from
www.sciencedaily.com/releases/2008/08/080804100139.htm
Julius-Maximilians-Universität Würzburg, JMU. (2017, July 6). Climate change threatens
domestic bee species. ScienceDaily. Retrieved May 23, 2018 from
www.sciencedaily.com/releases/2017/07/170706072059.htm
Kluser, S., Neumann, P., Chauzat, M., & Pettis, J. (2010). UNEP emerging issues: global
honey bee colony disorder and other threats to insect pollinators. Retrieved from
https://www.unenvironment.org/resources/report/unep-emerging-issues-global-honeybee-colony-disorder-and-other-threats-insect
Le Conte, Y., & Navajas, M. (2008). Climate change: Impact on honey bee populations and
diseases. Retrieved from
https://www.researchgate.net/publication/23285587_Climate_change_Impact_on_hon
ey_bee_populations_and_diseases
Bee Diseases and their Control. (2005). Retrieved from
http://agdev.anr.udel.edu/maarec/educational-resources/maarec-fact-sheets/
BEE EXTINCTION
Sanchez-Bayo1, F., & Goka, K. (2016). Beekeeping and Bee Conservation - Advances in
Research [Ebook] . InTech Open Science. Retrieved from
https://www.researchgate.net/publication/303383481_Impacts_of_Pesticides_on_Hon
ey_Bees
SPIVAK, M., MADER, E., & VAUGHAN, M. (2011). The Plight of the Bees. Retrieved
from
https://pdfs.semanticscholar.org/780b/df12fb876ec647c9755a68f930f5bff180db.pdf
Tosi, S., Nieh, J., & Burgio, G. (2017). Common Pesticide Damages Honey Bee’s Ability to
Fly. Retrieved from
https://ucsdnews.ucsd.edu/pressrelease/common_pesticide_damages_honey_bees_abil
ity_to_fly