The Mysteries of Colony Collapse

May 15, 2014

COLONY COLLAPSE DISORDER (CCD) of honey bees is one of the lingering mysteries of early 21st Century science in more ways than one: from its microbial, immune system and genetic components to an amorphous almost Orwellian terminology as imprecise and ambiguous as climate change (a slogan wide enough to encompass warming up, cooling down, and even staying the same temperature while the numbers fluctuate around the mean or average). The ambiguous language says both nothing and everything simultaneously, though underlying CCD is a quest for as yet unknown changes in insect rearing circumstances that will produce non-collapsing honey bee colonies. During the 19th century (1800s), a century marked by worldwide famines in the the old colonial empires and phylloxera-ravaged wine-grape vineyards collapsing in France, a revolution in modern medicine was being birthed in the mysteriously collapsing silkworm colonies. Fortunately for lovers of silk fabrics, fashion and textiles, 19th century silkworm farmers had the services of the real-life scientific Sherlock Holmes of the era, the famous French freelance scientist and sometime entomologist, Louis Pasteur.

Pasteur had a knack for solving applied problems like fermentation (beer, wine, vinegar) and silkworm colony collapse, and then using the results to develop broader theories like germ theory, which taught modern doctors to wash their hands and sterilize their instruments so as to stop spreading the germs that commonly killed their patients. How Pasteur almost single-handedly accomplished so much more than whole scientific institutes seemed able to do in the 20th century was the subject of an illuminating mid-20th century book, Louis Pasteur Free Lance of Science, by French-borne microbiologist Rene Dubos. “Toward the middle of the nineteenth century a mysterious disease began to attack the French silkworm nurseries,” wrote Dubos. “In 1853, silkworm eggs could no longer be produced in France, but had to be imported from Lombardy; then the disease spread to Italy, Spain and Austria. Dealers procuring eggs for the silkworm breeders had to go farther and farther east in an attempt to secure healthy products; but the disease followed them, invading in turn Greece, Turkey, the Caucasus–finally China and even Japan. By 1865, the silkworm industry was near ruin in France, and also, to a lesser degree, in the rest of Western Europe.”

“The first triumphs of microbiology in the control of epidemics came out of the genius and labors of two men, Agostino Bassi and Louis Pasteur, both of whom were untrained in medical or veterinary sciences, and both of whom first approached the problems of pathology by studying the diseases of silkworms,” wrote Dubos, who between World Wars I and II worked at the League of Nations’ Bureau of Agricultural Intelligence and Plant Diseases as an editor of the International Review of the Science and Practice of Agriculture. “A disease known as mal del segno was then causing extensive damage to the silkworm industry in Lombardy. Bassi demonstrated that the disease was infectious and could be transmitted by inoculation, by contact, and by infected food. He traced it to a parasitic fungus, called after him Botrytis bassiana (since renamed Beauveria bassiana, a widely used biocontrol agent)…An exact understanding…allowed Bassi to work out methods to prevent its spread through the silkworm nurseries. After twenty years of arduous labor, he published in 1836…Although unable to see the bacterial agents of disease because of blindness, Bassi envisioned from his studies on the mal del segno the bacteriological era which was to revolutionize medicine two decades after his death.”

Chemist Jean Baptiste Dumas, Pasteur’s mentor, prevailed upon the reluctant free lance scientist to head a mission of the French Ministry of Agriculture. “Although Pasteur knew nothing of silkworms or their diseases, he accepted the challenge,” wrote Dubos. “To Pasteur’s remark that he was totally unfamiliar with the subject, Dumas had replied one day: ‘So much the better! For ideas, you will have only those which shall come to you as a result of your observations!’”

A way of life was also at stake. As described in 19th century France by Emile Duclaux, Pasteur’s student and intimate collaborator (in Dubos’ book): “…the cocoons are put into a steam bath, to kill the chrysalids by heat. In this case, scarcely six weeks separate the time of egg-hatching from the time when the cocoons are carried to market, from the time the silk grower sows to the time when he reaps. As, in former times, the harvest was almost certain and quite lucrative, the Time of the Silkworm was a time of festival and of joy, in spite of the fatigues which it imposed, and, in gratitude, the mulberry tree had received the name of arbre d’or, from the populations who derived their livelihood from it.”

“The study of silkworm diseases constituted for Pasteur an initiation into the problem of infectious diseases,” wrote Dubos, who was influenced by the famous Russian soil microbiologist, Serge Winogradsky, who favored studying microbial interactions in natural environments rather than in pure laboratory cultures. “Instead of the accuracy of laboratory procedures he encountered the variability and unpredictability of behavior in animal life, for silkworms differ in their response to disease as do other animals. In the case of flacherie (a disease), for example, the time of death after infection might vary from 12 hours to 3 weeks, and some of the worms invariably escaped death…Time and time again, he discussed the matter of the influence of environmental factors on susceptibility, on the receptivity of the ‘terrain’ for the invading agent of disease. So deep was his concern with the physiological factors that condition infection that he once wrote, ‘If I had to undertake new studies on silkworms, I would investigate conditions for increasing their vigor, a problem of which one knows nothing. This would certainly lead to techniques for protecting them against accidental diseases.’”

“Usually, the public sees only the finished result of the scientific effort, but remains unaware of the atmosphere of confusion, tentative gropings, frustration and heart-breaking discouragement in which the scientist often labors while trying to extract, from the entrails of nature, the products and laws which appear so simple and orderly when they finally reach textbooks and newspapers,” wrote Dubos. “In many circumstances, he developed reproducible and practical techniques that in other hands failed, or gave such erratic results as to be considered worthless. His experimental achievements appear so unusual in their complete success that there has been a tendency to explain them away in the name of luck, but the explanation is in reality quite simple. Pasteur was a master experimenter with an uncanny sense of the details relevant to the success of his tests. It was the exacting conscience with which he respected the most minute details of his operations, and his intense concentration while at work, that gave him an apparently intuitive awareness of all the facts significant for the test, and permitted him always to duplicate his experimental conditions. In many cases, he lacked complete understanding of the reasons for the success of the procedures that he used, but always he knew how to make them work again, if they had once worked in his hands.”

Though famed for disproving the spontaneous generation of life, immunization via attenuated living vaccines and the germ theory of infectious disease: “Pasteur often emphasized the great importance of the environment, of nutrition, and of the physiological and even psychological state of the patient, in deciding the outcome of the infectious process,” wrote Dubos. “Had the opportunity come for him to undertake again the study of silkworm diseases, he once said, he would have liked to investigate the factors which favor the general robustness of the worms, and thereby increase their resistance to infectious disease…A logic of Pasteur’s life centered on physiological problems is just as plausible as that which resulted from the exclusive emphasis on the germ theory of contagious disease.”

The 21st century is riddled with insect colony conundrums and mysteries. For example, why among the social insects are honey bees plagued by Colony Collapse Disorder, while “Colony Expansion Disorder” prevails for other social insects in the USA. Rather than collapsing, USA colonies of Argentine ants are forming “super-colonies,” and red imported fire ant colonies are growing stronger by the day and annually expanding their North American geographic range; this despite being deliberately dosed with pesticides and attacked by biocontrol organisms (perhaps even more so than the beleaguered honey bees). And quite independently of mortgage rates and housing sales, Formosan subterranean termite colonies damaging billions of dollars of USA housing stock are happily munching away at both live trees and “dead-tree” wooden housing assets with little collective danger of colony collapse, though individual colonies come and go.

Perhaps beekeeping and crop pollination would be easier if Colony Collapse Disorder were an actual “disorder” as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM), and honey bees were endowed with sufficient consciousness and behaviors amenable to bee psychology or psychiatry.

The very real plight of honey bee colonies or hives is still in what Dubos would call the “atmosphere of confusion, tentative gropings, frustration.” At the most recent Entomological Society of America annual meeting, roughly a century and a half after silkworm colony collapse was eliminated by better more sanitary rearing practices, honey bee health was still puzzling. Honey bee colony loss in Virginia increased to 30% from 5-10% in recent years, possibly due to disease pathogens, pesticides and immune system suppression, say Virginia Tech researchers (e.g. Brenna Traver) studying glucose oxidase (GOX), an indicator of immunity in social insects. Honey bee social immunity is complex, involving factors as diverse as pheromones and grooming, and honey bee production of hydrogen peroxide (H2O2), which sterilizes food for the colony.

Nosema ceranae, a global gut pathogen, was seen all around the USA in 2007 at the same time as Colony Collapse Disorder. Black queen cell virus is another culprit, along with deformed wing virus, which is spread among honey bees by varroa mites. Then it is hard to overlook that over 120 different pesticides and their metabolites have been found in honey; including common beekeeper-applied pesticides such as coumaphos, fluvalinate, chlorothalonil and the antibiotic fumagillin. At the University of Puerto Rico, Gloria Dominguez-Bello is testing oxytetracycline and other commonly used antibiotics for their effects on honey bee microbes similar to those known to affect everything from obesity and brain function to organ transplants.

Those familiar with Pasteur’s entomological research on silkworm colony collapse in the 1800s would have experienced a sense of deja vu at the most recent Entomological Society of America meetings listening to Gloria DeGrandi-Hoffman, a research leader at the USDA-ARS Carl Hayden Bee Research Center in Tucson, Arizona. Nutrition, stress and pesticides may indeed be involved, but more focus is warranted for honey bee microbial health and gut microbes. Honey bee nutrition and microbiology is complicated by seasonal variations with changing food sources. According to DeGrandi-Hoffman, a lack of beneficial microbes may set honey bees up for infectious diseases like chalkbrood.

For example, pesticides used for Varroa mite control and potent beekeeping antibiotics like thymol and formic acid can affect the Lactobacillus microbes bees need for digestion and preservation of pollen as beebread, said DeGrandi-Hoffman. When bacterial plasmids found in high numbers in beebread are plated with the pathogen Aspergillus flavus, the pathogen rapidly loses virulence.

It is likely honey bees rely on beneficial microbes to protect from harmful pathogens, as honey bees have among the fewest immune system genes of any insect. Thus, when California almond growers spray fungicides, insecticides and miticides, a side effect could be fewer beneficial microbes in honey bee guts and in beebread. Thus, the honey bees would be less healthy and more susceptible to diseases like chalkbrood. Probiotic supplements designed to add beneficial microbes to honey bee diets are being tested in some California orchards. No doubt a familiar concept to those shopping for probiotic yogurts.

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Earthworm Compost, Medicinal Honey & Fewer Hive Sprays Avert Bee Collapse

April 4, 2012

HONEY BEE COLONY COLLAPSE DISORDER and subtle learning and memory pesticide effects were among Biocontrol Beat topics detailed in Feb. 2011 (Honey Bees, 24-Hour Surveillance Cameras & Pesticides). For many attendees of Entomological Society of America (ESA) annual meetings, the two reports on pesticide effects on honey bees and bumble bees in the 30 March 2012 issue of Science magazine were just two more data bits, nothing particularly surprising; albeit good headline news fodder and a bit troubling. Perhaps a slight feeling of déjà vu for those familiar with Rachel Carson and her book of more than half a century ago, Silent Spring.

To imbibers of energy-boosting, nervous system stimulants like coffee, tea, and the many other caffeinated beverages flooding the marketplace, the idea that a common natural (e.g. botanical) or synthetic chemical might affect behavior is almost a no-brainer, though not necessarily self-evident. Caffeine has gone from fruit fly studies to mosquito control remedy recently. Natural nicotine from tobacco family plants has had almost an opposite trajectory, having once been widely used (e.g. burned as a fumigant) and recommended (e.g. soaking cigarette butts in water) for pest control in agriculture, greenhouses, and organic gardens; and now shunned because of its toxicity to humans and beneficial insects.

Neonicotinoid pesticides, like the widely used imidacloprid, had their design inspiration in natural nicotine molecules; but are safer to humans and other animals. But perhaps not totally without adverse effects, if indeed it is possible to have a substance that is toxic and yet totally safe. The Science reports associate neonicotinoid chemicals like imidacloprid with reduced bumble bee colony size and queen production, as well as lower honey bee survival and foraging success.

Though the scientific data will be subjected to further debate and future studies may confirm or refute the results, Science magazine writer Erik Stokstad, in an accompanying news and analysis, marshaled a stunning statistic to go with the reports: “In the United States alone, 59 million hectares of crops are protected by systemic pesticides. Seeds are treated with these neurotoxins before planting, and the poison suffuses the tissues, pollen, and nectar…”

Nonetheless, as ESA annual meeting habitués may know: genetics, pathogens, parasites, and beekeeper practices apparently also figure into the still mysterious honey bee Colony Collapse Disorder (CCD). Perhaps aptly for a confusingly mysterious disorder, CCD, the acronym for Colony Collapse Disorder, is confusingly the same as the Community College of Denver, charged-coupled devices (like those capturing images in digital cameras), Confraternity of Christian Doctrine, and The Convention Centre Dublin, to mention but a few highly-ranked “CCD” terms in Google.

Those who put their faith in scientific panels, better testing, and more government regulation will be heartened to know that Stokstad says more is on the way in Europe and the USA. Those wanting to do something practical right now to help the honey bees and native bumble bees pollinating their backyards and fields might find more encouragement in some of the presentations coming out of the Entomological Society of America (ESA) annual meetings.

For example, North Carolina State University soil ecologist Yasmin Cardoza, who has shown that earthworm compost produces plants more resistant to caterpillar pests and aphids, more recently told the ESA that amending a cucumber soil (model system) with earthworm compost (vermicompost) helped bumble bees and other native pollinators become heavier, healthier, and more fecund.

Cucumber plants grown in soils amended with earthworm compost had flowers (pollen, nectar) with significantly more protein and a bit more sugar. These more nutritious flowers grown with earthworm compost attracted more bumble bees and native pollinators. Plus the bumble bees had more and larger ovary cells and egg tubes (i.e. an indication of enhanced reproduction), weighed more, and had fewer disease pathogens. Whether earthworm compost can reverse or prevent Colony Collapse or create Colony Expansion would make for an interesting study.

Beekeeping methods also take a hit for exacerbating honey bee problems; and are illustrative of how mites, insect pests and pesticides make for the type of challenging problem that in previous centuries were solved by privately-funded freelance scientists like Louis Pasteur. Pasteur’s freelance entomological endeavors included almost single-handedly rescuing the nineteenth-century silk industry from a similar mysterious collapse of silkworm colonies (insect colonies seem particularly prone to epidemic collapse when you want them; but resistant to collapse when you would rather be rid of them, like termite and fire ant pests). Rene Dubos’ account in his 1950 book, Louis Pasteur Free Lance Of Science, is well worth reading for free on the Internet (pdf, Kindle versions). By early twenty-first century standards, Pasteur seems almost like a Rambo of science, accomplishing with a few assistants what would seem impossible today.

Even if the cause of honey bee colony collapse is still mysterious, like silkworm colony collapse was prior to Pasteur, there is no doubting the reality of the problem.

“In Virginia, the number of managed honey bee colonies have declined by about 50% since the late 1980s due to the introduction of parasitic mites,” Virginia Techie (Blacksburg, VA) Jennifer Williams told the ESA. “Excessive reliance” on fluvalinate (a pyrethroid miticide) and coumaphos (an organophosphate miticide) have “been implicated in numerous problems to honey bees, including impaired reproductive physiology, reduced ability of colonies to raise queens, reduced sperm viability in drones (males), and increased queen failure and loss.” Often these miticides are found in combination with imidacloprid (systemic insecticide), chlorothalonil (broad-spectrum fungicide), and the broad-spectrum antibiotics oxytetracyline and streptomycin used by beekeepers to combat American foulbrood disease in honey bee hives.

Fluvalinate, coumaphos, coumaphos-oxon, and chlorothalonil are found in almost half of North American honey bee colonies at ppb (parts per billion) levels that can be acutely toxic. Combining miticides, pesticides, and antibiotics is a toxic cocktail recipe boosting honey bee mortality 27-50%, according to Williams. In other words, it is a vicious circle in which beekeeping practices (e.g. miticides, antibiotics, substituting sugar water for honey) may have deleterious effects offsetting curative effects on already weakened and mentally confused bees feeding on plants treated with pesticides rather than healthy composts like those being studied by Cardoza.

As if honey bees did not have enough health problems, the small hive beetle (Aethina tumida) is now part of the mix. “In their native range in South Africa, these beetles cause relatively little damage,” Natasha Wright of the University of Arkansas told the ESA. “However, they can be destructive to honey bee colonies in the United States and Australia. The adults and larvae feed on bee brood and bee products. They also cause honey to ferment, which results in unsellable honey. Little is known about the biological control agents.”

“Identifying new mechanisms that support honey bee health will be pivotal to the long-term security and productivity of American agriculture,” Emory University’s Lydia McCormick told the ESA. “Hydrogen peroxide is a potential natural defense/stress response to small hive beetle,” a pest which can devastate a honey bee colony in weeks or months. Not to knock beekeepers, who have enough problems already, but their practice of feeding bees sugar water rather than honey laced with hydrogen peroxide may be part of the problem. Honey bees produce more hydrogen peroxide in their honey to combat stressors like the hive beetle.

“Extremely low concentrations of hydrogen peroxide in sugar-water fed samples may represent a problem in this common method of hive management,” said McCormick. “Honey bees may selectively regulate higher brood honey hydrogen peroxide as a strategic oxidant defense. Given that brood cells contain honey bee larvae, high honey hydrogen peroxide may help protect against pests.” Indeed, small hive beetle survival is lower with hydrogen peroxide in the honey.

Honey containing hydrogen peroxide has been marketed for its antibacterial, wound healing, and skin care potential; and prescriptions for medical-grade honey are a possibility. New Zealand professor Peter Charles Molan published an interesting historical review on honey for wound healing in 2001. Besides hydrogen peroxide, honey may have healing botanical compounds (phytochemicals). Perhaps the bee’s loss is humankind’s medical gain. Though if the bees are lost as pollinators in the process, it is not a sustainable practice in the longer-term.


Asian Innovations in Insect Control

August 20, 2011

Innovations in Insect Control in Asia date back almost 2,000 years to when ancient Chinese farmers learned the art of biological insect control. China’s ancient orchardists annually introduced colonies of predatory ants to cultivated trees to control caterpillars and other pests of crops such as citrus. Ancient Chinese biocontrol practices included constructing bamboo bridges between trees, so predatory ants could easily wander from tree to tree foraging for pests.

Fast forward to the twenty-first century: Tea is arguably the second most widely consumed beverage, after water. Tea production occupies 2.7 million ha (6.7 million acres) in 34 countries, with 78% of production in Asia and 16% in Africa. Sustainable tea production practices emphasize displacing pesticides with cultural and biological control practices to control spider mites and other pests in tea plantations.

“The application of natural enemies in tea pest control aroused a large amount of investigations in the tea producing countries,” reported Yang Yajun and colleagues at the Tea Research Institute of Chinese Academy of Sciences at the 2005 International Symposium on Innovation in Tea Science and Sustainable Development in Tea Industry. “In South India, investigations showed the introduction of three species of entomophagous fungi in the control of tea spider mite (Oligonychus coffeae). In Japan, the use of pesticide-resistant predatory mite resulted in successful control…In Japan, one fungal preparation and one bacterial preparation were registered and used in control of tea diseases.” In China and Japan, viruses stop pesky leafrollers and loopers. Japan also has five fungal biocontrol products, one bacterial biocontrol preparation, and several kinds of parasitic and predatory natural enemy preparations to control tea insect pests.

“Great achievements in the application of physical and agricultural control methods in controlling the tea pests were advanced,” said Yajun et al. In Japan, China, and Malawi (Africa), yellow sticky traps and reflective films (near ultra-violet light) help control tea aphids, thrips, and leafhoppers (70-80% pest reduction). “A special mist wind insect-sucking machine was developed in Japan,” and it reduces tea leafhopper, whitefly, and spider mite populations.

Sex pheromones have been used for mating disruption in Japanese tea gardens since 1983 to control a pesky tea leafroller. Sex pheromones are also being used against other tea pests in Japan and China. Natural volatiles from the tea plant that attract natural enemies but not pests are also under development. For example, the April 2004 Chinese Journal of Applied Ecology (15(4):623-626) reported that beneficial lady beetles, green lacewings, and hover flys (syrphids) controlling tea aphids were attracted by natural compounds such as nerol from tea flowers, n-octanol from intact tea shoots, and geraniol, methyl salicylate, benzaldehyde, and hexanal from aphid-damaged tea shoots.

At Entomological Society of America (ESA) annual meetingss, California Department of Food and Agriculture (CDFA) officials report that T. Kanzawa’s 1939 translation of Professor Dr. Shonen Matsumura‘s 1931 book, 6000 Illustrated Insects of Japan-Empire, is still used to help with identification and control of invasive insect pests like the dusky-winged fruit fly (Drosophila suzukii). Oregon entomologist Jana Lee told the ESA that the Japanese get 100% fruit fly protection by placing 0.98 mm (0.04 inch) mesh over blueberries 20 days pre-harvest. After the harvest, 100% of fruit fly eggs and newly hatched larvae on cherries are killed by holding the fruit at 1.6-2.2 C (29-36 F). In Japanese experiments, fruit fly egg laying in cherries was reduced 30-60% with botanicals such as eucalyptus, neem, and tansy. In other promising Japanese research, Kotaro Konno and Hiroshi Ono told the ESA that latex from the same mulberry leaves used to safely grow silkworms since ancient times could be an effective botanical insecticide against other pests.

Since the 1920s, the USDA has been importing Japanese and Korean biocontrol organisms, like Tiphia wasps to control Oriental beetles and Japanese beetles attacking golf courses, turf, crops, and landscape ornamentals. Japan is currently patenting decoy tree technologies to help stop an explosive outbreak of oak wilt fungus (Raffaelea quercivora), caused by mass attacks of ambrosia beetles (Platypus quercivorus), said Masahiko Tokoro of the Forestry and Forest Products Research Institute (FFPRI) in Ibaraki, Japan (See earlier blog post: The Asian Invasion -Insects in Global Trade).

In South Korean greenhouse tests, Sangwon Kim and Un Taek Lim of Andong National University told the ESA of greenhouse tests showing the superiority of yellow circles against a black background versus conventional rectangular yellow sticky traps for capturing pesky whiteflies and thrips. “In laboratory behavioral studies using different backgrounds and shapes, yellow sticky card with black background was 1.8 times more attractive than sticky card without background, and triangle attracted 1.5 times more sweetpotato whitefly (Bemisia tabaci) than square,” said Kim. Black sticky cards with small yellow circles caught 180% more sweetpotato whitefly than cards with larger circles.


Honey Bees, 24-Hour Surveillance Cameras & Pesticides

February 22, 2011

HONEY BEE HEALTH had the entomologists buzzing and the grad students searching for answers at the Entomological Society of America (ESA) annual meeting in San Diego. For several years now specialists have been spinning speculative theories as to why the pollinating honey bees of commerce, mostly the species known as Apis mellifera, have been in such sad shape. Isaac Newton had the proverbial apple bonk him awake to gravity. Bee entomologists have not yet had that magical bee sting in the butt “Aha” moment.

But there seems no getting away from the problem, as keepers of bee hives an ocean away from the USA are also getting stung with big losses, from what is dubbed colony collapse disorder (CCD). What has entomologists scurrying to their Petri dishes and bee hives and firing up surveillance cameras, chromatographs and mass spectrometers is a study titled “High Levels of Miticides and Agrochemicals in North American Apiaries: Implications for Honey Bee Health.” Christopher Mullin of The Pennsylvania State University, a self-described connoisseur of how poisons work, and several colleagues “found 121 different pesticides and metabolites within 887 wax, pollen, bee and associated hive samples” from 23 states and one Canadian province. Enough to induce sleep-loss and second thoughts about the health and sleep-inducing effects of commercial honey products.

Surveillance cameras, 24-hours a day, are the best way to monitor and gather numerical data on how pesticides affect honeybees, Cornhusker grad student Bethany Teeters told the ESA in her prize-winning poster, “Bees under surveillance.” Being more video than even an insomniac can sanely watch, the University of Nebraska-Lincoln entomology lab delegates the task to “state-of-the-art detection” software: namely EthoVision XT, which Noldus Information Technology calls “the most widely applied video tracking software that tracks and analyses the behavior, movement, and activity of any animal” from “lab animals in mazes to farm animals in stables.” No doubt what Geoge Orwell would have used in his Animal Farm novel, had he written it in 2011 rarther than 1946.

“Honey bees are exposed to sublethal doses of pesticides on a regular, often chronic, basis,” Teeters told the ESA. “For instance, the pyrethroid tau-fluvalinate (Apistan(R)) is one of many pesticides applied directly into the hive to control the parasitic mite Varroa destructor. Although tau-fluvalinate is considered safe for honey bees, potential effects of sublethal intoxication remain unexplored.” Same goes for coumaphos, also used to treat for Varroa mites.

“Honey bees may also encounter sublethal doses of pesticides while foraging,” said Teeters. “Systemic pesticides, including the neonicotinoid imidacloprid, have become prominent in U.S. crop pest management. This raises concerns about the consequences of sublethal exposure to systemic pesticides in nectar and pollen that honey bees visit in addition to chronic exposure to residues in the hive. Decline in colony health has been associated with ppm (parts per million) pesticide residues in hive products, and the neonicotinoid can impair honey bee health at ppb (parts per billion) levels.”

Teeters surveillance videos of bees exposed to sublethal pesticide doses in Petri dishes revealed that bees exposed to tiny traces of tau-fluvalinate spend more time socially interacting. Bees exposed to imidacloprid spend less time socially interacting and more time eating. Next step is studies to see if this is true in actual honey bee hives, and whether colony health is impacted.

Natalie Boyle, a graduate student at Washington State University in Pullman, studied the effects of Varroa mite pesticides on honey bee hives in Moscow, Idaho. Honey bee adults stressed by miticide residues died sooner and did less reproductive swarming. But they compensated with increased brood production. “While our results are preliminary, if we find that pesticide residues in brood comb adversely affect colony health, it would suggest that regular brood comb replacement in beekeeping operations might be a suitable management strategy,” said Boyle. “Similarly, approaches to reduce miticide applications in beehives and pesticide exposure in agricultural field settings would be highly beneficial.”

Back at The Pennsylvania State University, graduate student Daniel Schmehl noted that the Varroa mite-killing chemicals coumaphos and tau-fluvalinate were found in almost every honey bee hive sampled in North America. Furthermore, these two chemicals were “associated with reduced queen weight and reduced ovary development.” After six days chronic exposure to tau-fluvalinate in cage studies, worker bees were less attracted to queen bees. This was possibly “due to changes in pheromone production from the queen or pheromone recognition by the workers.”

On the West Coast, at the University of California, San Diego, graduate student Daren Eiri explored how sublethal doses of the pesticide imidacloprid can subtly alter foraging habits in ways that weaken honey bee colonies. A common lab assay used to assess foraging is stimulating the honey bee antenna with sucrose, which elicits the proboscis (tongue) extension reflex (PER). PER is the lab equivalent of natural honey bee behavior in the field when foragers are stimulated by nectar. The pesticide seemed to make the bees “become pickier when foraging for nectar sources, possibly limiting the colony intake and storage of their only carbohydrate.” Pollen foraging may also be reduced, and “the colony would therefore suffer a protein deficit, resulting in lessened brood production and a dwindling population.”

Though the mystery of colony collapse disorder (CCD) is far from solved, current agriculture practices do not seem to be making honey bee colonies healthier, to say the least. But the collapse of the imported honey bee may have a silver lining: It is spurring agriculture to turn to previously neglected native pollinators. But the rise of the native pollinators is another story, for another time.


Rainy Days Wash Pests Away

October 26, 2009

WORLD WAR II was raging around The Netherlands from 1941 to 1944. But in Zeeland province entomologist D.J. Kuenen slogged on with his solitary, long-term studies of climate and rainfall effects on fruit tree red spider mites in apple and plum orchards. Even under the best conditions in peacetime, long-term ecological field studies that could aid in natural pest control are few and far between. The reason is simple: longterm ecological field studies are an expensive, labor-intensive, problematic way to advance a career in academia. The more-assured path to tenure and gainful employment is a series of quick, narrowly-focused lab studies yielding a plethora of speedily published papers in scholarly journals.

DDT and the synthetic pesticide era, along with high-yield chemical farming, exploded in the years immediately after World War II. The tedious years of meticulously gathered data on natural pest control from wind and rainfall (a form of overhead irrigation) was consigned to languish for decades under layers of library dust in tiny articles in obscure journals. Kuenen and his predecessors studying the pest control efficacy of wind and high-pressure water sprays were several decades ahead of their time. Much like the monk Gregor Mendel’s now-celebrated genetic experiments growing wrinkly and smooth garden peas.

Today, the pendulum is swinging back to more natural forms of pest control. Kuenen and his Roaring Twenties predecessors studying wind and rain as natural forms of pest control would be warmly welcomed at sustainable agriculture gatherings today. Ecological field studies showing that heavy rain showers and wind storms blasted away 90% of pesky spider mites would be spurring graduate students and inventive farmers to simulate the natural pest control benefits with artificial wind and water blasts from hoses, sprinklers, and other devices.