BEEINFOrmed N° 1_2014

LEARNINGS FROM THE PAST

BEE MORTALITY AND ITS PRESENT-DAY RELEVANCEFor many millennia in human history, honey was the only sweetener known to mankind. The honey bee’s

culinary and economic significance is one reason why there is no shortage of historical records on bee

mortality. The insights gained into the pathological history of bees can help us see the current debate on

the causes of bee mortality in a more balanced light. And the history of bee care at Bayer in recent decades

illustrates what this agrochemical company has been doing to preserve these vital beneficial insects.

Why Pathological History Matters

The importance of historical research in understanding animal diseases was emphasized in a groundbreaking book published in London as long ago as 1871. The author, George Fleming, was President of the Central Veterinary Medical Society and a member of the Royal College of Veterinary Surgeons. In the introduction to his epic work covering “Animal Plagues: Their History, Nature, and Prevention” from 1490 BC to 1800 AD, Fleming had this to say about the significance of pathological research:

“A record of epizootic diseases founded on history and accurate observation cannot fail to be a work of great importance to medical science and to civilization […]. The comparative pathologist can no more afford to dispense with the history of diseases then the healer of mankind [...] or in proportion as he knows the past, he is in a better position to control the present, and make provision for the future.”

And in quoting Hecker (Annalen, 1828), Fleming comes up with a statement of remarkable relevance to the present-day debate on the causes of bee mortality: “Men gazed at the phenomena with astonishment, and even before they had a just perception of their nature, pronounced their opinions, which, as they were divided into strongly opposed parties, they defended with all the ardor of zealots.” He could have been writing about the present-day controversy concerning the real factors affecting bee health.

George Fleming (1833–1901)

by B. Hudson

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Beehive stone house, Ireland Antique beehives from Puertomingalvo, Spain Ancient Egyptian carving of beekeeper with hives Sculpture of a dome-shaped hive, Denmark 1823

Historical Hurdles

Important though the pathological history of animals undoubtedly is, any study of the numerous historical sources soon comes up against grave hurdles. From ancient times up to the 18th century, blind faith and superstition clouded men’s minds as they sought to attribute a cause to a specific disease – whether of humans or animals. With little knowledge of veterinary science, ancient and medieval man mostly ascribed animal diseases to divine retribution or evil spirits. Their “divine explanation of animal plagues” (Fleming) has left us with historical records that frequently describe the calamities such plagues brought about, vaguely describe the symptoms, and nearly always attribute the maladies to some angry deity. Consequently, the modern-day historian can do little more than cite meager facts about bee mortality from the earliest days of beekeeping in Ancient Egypt to the 18th-century Age of Enlightenment. As in many other fields of science, the Enlightenment finally directed the revealing light of science onto the dark annals of animal pathology. A true trailblazer in the objective study of animal diseases, the Italian physician and philosopher Bernadino Ramazzini (1633-1714), laid the foundations for accurate observations in this field of veterinary science.

Mankind’s only Sweetener

For many millennia honey was “the only sweetener available to early Af-rican, Middle Eastern and European civilizations” (vanEngelsdorp et al., 2009). To this end, bees were domesticated by the Ancient Egyptians be-fore 2600 BC. By the 7th century BC the Ancient Greeks were also keep-ing bees and their apian skills were passed on to the Romans around 150 BC. The art of beekeeping was then disseminated throughout the Roman Empire and became widely practiced in early medieval Europe. It was the emigrating descendants of medieval European beekeepers who took bees and the art of beekeeping around the globe.

As the only available sweetener available in Europe until the technology was developed to refine sugar from sugar beets and sugar cane, honey was an economically important commodity – a role it still plays today, but for different reasons. By far the most important contribution honey bees make to today’s global economy is as pollinators. Studies have shown that 52 of the 115 leading global food commodities are dependent on pollination by bees and other insects, which directly or indirectly benefits 35% of our human diet (Klein et al, 2007). 5,000 Years

For nearly five thousand years, honey bees have made a major contribution to our well-being, a fact that also accounts for the wealth of historical records on bee mortality.

90% of the world’s food Of the 100 crops providing

70 benefit from pollination by bees and other insects.

Prehistoric Extinction Event

The earliest known case of mass bee extinction was in prehistoric times. One bee subfamily, the Xylocopinae, was virtually wiped out around 65 million years ago, close to the so-called K-T boundary between the Cretaceous and Paleogene eras. In an article published in the academic journal Plos One in October 2013, Sandra Rehan and her team of biologists from the University of New Hampshire describe how they used molecular evolutionary relationship analyses to show that this mass extinction killed off non-avian dinosaurs and many flowering plants. And it was during the mid-late Cretaceous period that bees had developed a co-evolutionary relationship with eudicot plants, a large subsection of the dicotyledon plant group containing most cultivated plants and many trees. The Cretaceous-Paleogene mass extinction event is believed to have been caused by a devastating change in the global climate, probably due to a massive comet or asteroid impact. Interestingly enough, most of the medieval bee mortality events Fleming records can also be linked to adverse weather conditions, though naturally on a vastly smaller scale.

Medieval Mortalities

Fleming’s earliest mention of bee mortality in medieval Europe is in Ireland in 950 AD, when the Annals of Ulster report a “mortality of bees”. Unfortunately, no further information is provided on this incident. In 992, again in Ireland, Fleming’s sources are more helpful since “a great mortality upon men, cattle and bees in Ireland” (Annals of Ulster) was preceded by “a long and severe winter, and an extremely dry summer followed by famine. The wheat crops were affected by blight [...] and the forage was generally of a bad quality”. Such weather conditions would also have had an adverse effect on flowering plants. As Fleming mentions, “bees were largely kept in Ireland at this time, and were a great source of wealth to the people”. In 1035 the Chronicle of Œfele reports that a very severe winter and extremely dry summer led to “unheard-of loss amongst animals, and this, with the destruction of bees, affected the whole of Bavaria”. The weather in England, in June of that year, was so cold that all the cereals and fruit

were destroyed. The climatic connection is again clear in 1124 when the Annals of Ulster record an eclipse of the sun on August 3rd, “which was followed by a great pestilence amongst oxen, sheep, pigs and bees. Even the crops failed.” A fascinatingly detailed record of animal diseases occurring in 14th-century England is contained in the Court Rolls of a Norfolk Manor recorded over a period of 63 years during the reigns of Edward III, Richard II and Henry IV. A murrain (disease) affecting bees is mentioned several times. In 1380, for example, as many as ten hives were lost and some losses were recorded in the apiary nearly every year for 20 years. Returning to Ireland, we discover a weather-induced mortality of bees in 1443 when the Annals of Ireland report “a rainy tempestuous year after May, so that [...] it much hurt both bees and sheep”.

Even these unscientific historical records from medieval Europe point to a clear causality: bad weather resulting in decreased nectar production, which in turn had a negative impact on colony productivity. This is entirely in line with modern-day research. As vanEngelsdorp et al. point out in their 2009 study of the factors affecting managed honey bee populations,

...“weather has a very real effect on colony welfare. Extended periods of cold, rainy or hot weather have been blamed for severe, oft unexplained, colony mortality in the past.”

Weather types can impact on the welfare of a bee colony

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Bernardino Ramazzini, 1633 to 1714, medica and physiologica

A quote normally attributed to Winston Churchill: “Those who fail to learn from history are doomed to repeat it” shows us why it makes sense to study all the factors that may contribute to bee mortality. And as Fleming so rightly said, the degree to which we know the past puts us in a better position to control the present, and make provision for the future.

Scientific Observations

The bee mortality accurately recorded by Bernadino Ramazzini in Lombardy in 1690 can be clearly attributed to adverse foraging conditions: “The heavy rains, which had almost unremittingly continued up to the end of June, were followed by a dry period of nearly two months [...] accompanied by great heat.” After noting the effects of these weather extremes on animals of every species, which “died in great numbers” as Ramazzini reports, “other animals suffered from the diseased plants. Even bees, extracting no sweetness from the calyces of the flowers, but a bitter poison, either died or left the country.” In 1717 there was a “great mortality amongst bees and carp in Silesia” in a year Fleming describes as generally cold with a cold and damp spring. 1780 saw an eruption of Mount Vesuvius and Mount Etna and in Saxony a disease or “rot” is recorded as affecting the eggs of bees from 1780 to 1783. This highly destructive egg rot reappeared amongst bees in Saxony from 1796 to 1803.

“The disease showed itself in 1796 after the bees had suffered much from the severe and long winter, and an unusually cold and hungry spring. It continued during similar springs, when the irregular weather and the severe storms damaged the vines.” (Die Faulbrut oder Bienenpest, Dresden, 1804)

This is a clear indication that the bee larvae had been affected by European Foulbrood (EFB), a disease caused by the gram-positive bacterium Melissococcus plutonius. Fleming’s great work takes us to the beginning of the 19th century, by which time the historical records of bee mortalities had become much more extensive and informative.

Bee Mortality in America

The earliest recorded shipment of bees to the Americas took place from England in 1621. By 1650 nearly all farms in New England are reported to have had one or two colonies of bees, but there is evidence that the number of bees managed by American colonists declined after 1670. In his “History of American Beekeeping” (1938) F.C. Pellett presumes the cause was American Foulbrood (AFB), a bacterial disease of the bee brood caused by the gram-positive bacterium Paenibacillus larvae. By the late 19th and early 20th century, AFB and EFB had become a “veritable scourge” in many parts of the country, as H.A. Surface showed in a 1916 study. Bee mortality in 20th-century America is of particular interest to the pathological historian because Colony Collapse Disorder (CCD) first came to light in the USA in 2006. As vanEngelsdorp et al. point out, “disease factors such as AFB and EFB have likely played an important role in honey bee colony declines in the USA over a century ago; however, their role in current overall declines is likely (to be) minimal.” In their 2009 study the authors conclude that:

“Varroa mites, together with the virus complex associated with mite parasitism, are likely (to be) one of the major causes for considerable overwintering losses documented by many northern nations over the last several years [...]. Modern pesticides with reduced acute toxicity may have sublethal effects that are more difficult to quantify. Additional factors, such as reduced bee forage, climate, narrowing of the gene pool, poor queens, and socio-economic factors all have measurable effects on managed honey bee populations.”

These acclaimed bee scientists come firmly down on the side of multi-causality in explaining bee mortality. According to the US Drought Monitor, this year 80% of the state California is under “extreme” or “exceptional” drought for the third year in a row, which – according to the US Department of Agriculture – has caused California´s honey crop to fall “sharply from 27.5 million pounds in 2010 to 10.9 million pounds last year”.

Unexplained Epidemics

Many of the bee epidemics recorded in detail in the more recent past remain unexplained. In 1903, 2,000 colonies were lost to an unknown “disappearing disease” in the Cache Valley of Utah. Significantly, however, the previous winter had been hard and the spring cold. In 1995-96, beekeepers in Pennsylvania lost 53% of their colonies to no specifically identifiable cause. One of the most infamous epidemics occurred on the Isle of Wight, a small island off the south coast of England, when three separate epidemics between 1905 and 1919 wiped out 90% of the island’s bees. As beekeepers noted, “many of their honey bee colonies were dying, with numerous bees crawling from the hive and unable to fly” (Neumann and Carreck, 2010). Beekeepers assumed that the condition was caused by a new and highly infectious disease, especially as there were reports of the “Isle of Wight Disease” affecting bees throughout Britain.

Many decades later, more detailed research into this epidemic (Bailey and Ball, 1991; Adam, 1968) led to the conclusion that the disease had actually been caused by a combination of factors, “in particular infection by chronic bee paralysis (completely unknown at the time), together with poor weather which inhibited foraging, and an excess of bee colonies being kept for the amount of forage available”. As Neumann and Carreck note, “the recent concern over CCD has much in common with the historical ‘Isle of Wight Disease’ episode, and many lessons can be learned.

Initial concern about colony losses in one particular area, the USA, has led to global media attention. Moreover, colony losses throughout the world are being ascribed to CCD, yet that term was specifically coined to describe a precisely defined set of symptoms (vanEngelsdorp et al., 2009) and not colony losses per se. Indeed, honey bee colonies can die in many ways, and CCD is just one of them.”

The “Isle of Wight Disease” and CCD

As the debate continues over the causes of CCD and other incidents of honey bee mortality, it is wise to remember the lessons of pathological history and be careful not to jump to overhasty conclusions.

Weather Conditions Key to lower 2013/14 Overwintering Losses

In July 2014 the independent honey bee protection network COLOSS announced the preliminary results of an international study to investigate honey bee colony losses in the winter of 2013/14. Data were collected from Israel, Algeria and 19 European countries. This study is statistically significant because of the many countries covered and the number of beekeepers who responded. In all, 17,135 beekeepers managing more than 376,754 colonies supplied COLOSS with overwintering mortality data. Overwintering losses in 2013/14 varied from 6% in Norway to 14% in Portugal and showed marked regional differences within most countries. The average overwintering loss for all 21 countries was 9%, the lowest figure since this international working group started collecting data in 2007. Just for comparison purposes, the average overwintering loss for the same period in England and Wales was 7.85% and the overwintering losses in the USA in 2013/2014 declined by 24% from the previous year. Also most Canadian provinces had significantly lower losses than in 2013. The coordinator of the COLOSS Monitoring and Diagnosis Working Group, Dr Romée van der Zee from the Dutch Centre for Bee Research, has this to say about the study findings: “The contribution of many factors which are correlated to colony losses seems to be very dependent on weather conditions. Colonies built their brood nests late because of the relatively cold spring in 2013. This may have decreased the number of reproductive cycles of the parasitic Varroa mite, producing fewer mites. Good weather in the summer then provided excellent foraging opportunities.” Once more, weather conditions have played a key role in influencing levels of bee mortality.

Honey bee development stages:

egg, larva, pupa

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Testing Crop Protection Products

As early as 1917, Bayer set up an independent Department for Plant Protection and Pest Control. That same year, the company purchased an estate, Gut Paulinenhof, close to its corporate headquarters in Leverkusen, because greenhouses and fields were needed for trials of new plant protection products. In 1940, Bayer acquired another farm, Gut Höfchen, and 180 hectares of land near Leverkusen where it established the world’s first experimental station solely dedicated to testing plant protection products. The apiary built for bee trials on the Gut Höfchen site is evidence of Bayer’s early commitment to the bee safety of its plant protection products. And it was not just in Germany that Bayer tested plant protection products from every possible perspective. In 1941, a testing station was set up in Japan; in 1962, Bayer purchased a farm near Monheim, just down the River Rhine from Leverkusen, for such trials; and in 1964, Bayer established another testing facility in Kaha near Cairo. Of the €3 billion Bayer now invests annually in R&D, significant sums are spent on testing plant protection products to ensure, among other things, their safety for beneficial insects.

Controlling Varroa Mites

Most bee health scientists would agree that the honey bee mite, Varroa destructor, is still the greatest threat to apiculture today. The Varroa mite is a relatively new parasite affecting the Western honey bee, having been introduced to Europe in the 1970s and to North America in the 1980s from Asia. Since then, it has spread to most of the world, except Australia, in a relatively short time. Varroosis, the Varroa-induced disease, affects both adult bees and the brood, and this parasite also affects honey bee health by spreading some 20 viruses that can result in deformed bees with missing legs or wings. Untreated infestations of Varroa mites can ultimately kill honey bee colonies.

Realizing the devastating effect this parasite could have on bee health if left unchecked, Bayer began developing effective medication for treating infested honey bee colonies. The first product launched was Perizin®, which was registered in 1986 as the first medication for oral treatment of hives without brood. This was followed in 1991 by registration of Bayvarol® and in 2001 of CheckMite+®, both as formulated strips for use in the topical treatment of brood-rearing colonies. The different active ingredients – coumaphos (Perizin® & CheckMite+®) and flumethrin (Bayvarol®) – and various formulations enable these treatments to be integrated into a wide range of pest control programs.

When applied correctly, these treat-ments can effectively control Varroa mite infestations in honey bee colonies. More recently, Bayer has continued to develop innovative solutions to tackle the Varroa mite and is currently developing a Varroa Gate technology to prevent initial infestation and also re-infestation of clean hives.

Varroa Gate Technology

Bees brush against the anti-mite

chemical on the entrance hole

when they return to the hive,

taking it inside with them. Fresh

supplies of the chemical are im-

mediately released from the core

of the plastic strip to its surface,

ensuring long-term rotection.

Bayer Bee Care Program

Bayer has been researching and developing products specifically designed to promote bee health for nearly 30 years. In 2011, Bayer took a strategic decision to establish its Bee Care program. As a result, two Bee Care Centers have been opened so far, one in Germany in 2012 and the other, serving North America, in April this year. In the recent past, Bayer has intensified its external collaborations to develop new solutions for bee health and provide information and support to various stakeholders. Such cooperation, Bayer believes, is essential in developing sustainable solutions to improve bee health.

Julian has worked in plant science and crop production for over twenty years. With a PhD in Molecular Plant Pathology from the University of Wales, he joined Rhone-Poulenc as a plant biochemist working in both the UK and France, and then in research project management in Aventis CropScience. Julian switched to communicating science in 2002 and is currently a Communications & Government Affairs Manager at Bayer CropScience UK. Based in Cambridge, he deals with media, political and public enquiries on the subject of crop production, innovative plant breeding, together with more general issues surrounding pesticide use and sustainable agriculture.

Author Dr Julian Little, Bayer Bee Care Team

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PHOTOSBayer CropScience: pp 2 right, 7 below Fotolia: 3Shutterstock: pp 1 above, 6, 7, 8 Royal College of Veterinary Surgeons: p 1 belowMural painting from the grave of Pa-bu-Sa, 630 BC: p 2 leftGeneva_ Cramer & Perachon, 1717: p 4 above

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Imprint

PUBLISHED SEPTEMBER 2014 BYBayer Bee Care CenterAlfred-Nobel-Straße 5040789 Monheim am Rhein | Germany beecare@bayer.com

LAYOUT AND ARTWORKageko . agentur für gestaltete kommunikation PRINTINGHH Print Management Deutschland GmbH

ILLUSTRATIONSBayer CropScience: pp 2, 4 below, 6 belowShutterstock: p 3 below, 6 above, 7 above

Sources Referred to in the Text:

Adam B (1968): “"Isle of Wight" or acarine disease: its historical and practical perspectives”. Bee World, vol. 49Bailey L, Ball BV (1991): “Honey bee pathology”. Academic Press, London, UKvanEngelsdorp D, Meixner MD (2009): “A historical review of managed honey bee populations in Europe and the United States, and the factors that may affect them”. Journal of Invertebrate Pathology Fleming G (1871): “Animal Plagues: Their History, Natury and Prevention” Hecker JFC (1828): “Annalen der gesammten Heilkunde” Klein AM, Vaissière BE, Cane J, Steffan-Dewenter I, Cunningham SA, Kremen C, Tscharntke T (2007): “Importance of pollinators in changing landscapes for world crops“ . The Proceedings of the Royal Society of LondonNeumann P, Carreck NL (2010): “Honey bee colony losses” (2010). Journal of Apicultural Researchhttp://www.researchgate.net/journal/0021-8839_Journal_of_Apicultural_Research Rehan S, Leys R, Schwarz MP (2013): “First Evidence for a Massive Extinction Event Affecting Bees Close to the K-T Boundary”. PLoS ONE