The Varroa destructor & tracheal mites, both invasives, have wrought havoc in the U.S. bee population. Perhaps the major debate in contemporary beekeeping is whether to try to treat to eradicate these parasites (so far, no one treatment has proven universally effective) and risk encouraging mite resistance, or not to treat, hoping that bees can thrive long enough to pass on survivor DNA.
Varroa mites lay their eggs in drone brood and hatch out with the bee; they puncture the exoskeleton of adult bees, becoming "phoretic" [a.k.a. "hitchhiker"] mites, and feed on the bee's hemolymph. In the process, Varroa mites create vectors through which diseases like deformed wing virus, Israeli acute paralysis virus, and others can infect the bee. Varroa infestation, in & 0f itself, does not kill honey bees, but weakens them such that other factors - diseases like these viruses, climate, Nosema, or pests like hornets - can wipe out an infected colony. Varroa mites co-evolved with the Asian Apis cerana bee and are thought to have entered the U.S. and European population in the 1980s through (largely illegal) imports. Apis mellifera, our European honey bee, is not well adapted to resist Varroa: the parasite came close to wiping out the U.S. feral honey bee population, as documented in the research of Debbie Delaney, among others. To view West Virginia University's informative page on Varroa, click here.
Tracheal mites inspired the 1922 Honey Bee Act, which has restricted bee importation to to the U.S. ever since. The Act did succeed in keeping these mites out of the U.S. for decades, but their presence was documented in 1984. Tracheal mites infest adult bees, taking up residence in their tracheal tubes until the bees can no longer breathe. Before that happens, though, the bees are reduced to crawling on the ground in front of the hive, unable to get enough air to lift off. Because these mites' action harms the wing muscles of the bee as well, the "K-shaped" wing is a telltale sign of tracheal mite infestation. To read more, visit Clemson University's page by clicking here.
Below, stories of research on ways to control these parasites. Stories include the recent phenomenon of so-called "zombie flies" and the threat of invasive Asian hornets.
“Parasite Pressures on Feral Honey Bees. Feral Colonies Are Pathogen Reservoirs,” 25 Aug 2014, Bee Culture
We know how damaging Varroa destructor can be for our managed colonies, but how does it affect feral honey bees? As it’s hard to sample ferals, given the places they tend to take up residence, no studies have focused on this until now. Uncertain genetic origins of feral colonies complicate these questions, too. Do ferals “represent a reservoir of Varroa tolerant material that could be used in apiculture”? In this study, researchers gathered foragers from “paired feral and managed honey bee colonies and screened for the presence of ten honey bee pathogens and pests.” What they found was that the rate of infestation was “similar” between the feral and managed bees. Yet “feral honey bees contained a significantly higher level of deformed wing virus than managed honey bee colonies.” Analysis of the wings of bees in both groups showed no obvious differences, “suggesting feral colonies could simply be escapees from the managed population.” The study also found that when managed colonies are not treated or Varroa, they show levels of deformed wing viruses similar to those of the feral colonies, “potentially lethal levels.” To read more, visit: http://home.ezezine.com/1636/1636-2014.08.25.09.15.archive.html.
“Of bees, mites, and viruses: Virus infections after arrival of new parasitic mite in New Zealand honeybee colonies”: 21 Aug 2014, Science Daily
The bad news is that Varroa mites have reached New Zealand; one of the few positives is that this new “viral landscape” can give new insights into Varroa infestations. This new study looks at interactions of bees, mites, and viruses, comparing European data with new information about Varroa in New Zealand. Would the New Zealand bees experience the “accelerated virus epidemic” that kills untreated colonies within two to three years? As the researchers monitored the beginning stages of Varroa infestations, they found that the mite “dramatically changed the viral landscape within the honeybee colonies of New Zealand,” with 7 separate viruses implicated. Deformed Wing Virus had “almost never [been] seen” in New Zealand bees before the mites arrived, but as Varroa numbers rose, so did DMV. Kashmir Bee Virus reached its height two years after the arrival of Varroa, then vanished, “leaving DWV as the dominant honeybee virus in long-term Varroa-infested areas.” However, the KBV seems to have helped weaken the colonies, suggesting that the interaction of viruses in the wake of Varroa infestation may be particularly dangerous. The researchers’ next steps "will focus on the mechanisms that form the evolutionary basis for the bee-Varroa-virus interaction."
“Scientists at the University of Warwick have discovered how a bloodsucking parasite has transformed Deformed Wing Virus (DWV) into one of the biggest threats facing UK honeybees”: 26 June 2014, Science Daily
Researchers have learned how Deformed Wing Virus “is amplified” by Varroa mites. When colonies are not infested by the mites, DMV, if present at all, “generally causes symptomless infections.” What the U. Warwick researchers found out was that “when Varroa feeds on honeybee haemolymph ('blood'), specific virulent strains of the virus are transmitted and amplified, explaining why colonies infested with the mite suffer most severely.” Further, “direct injection of a mixed DWV population in the absence of the mite, resulted in the same virulent strain being amplified -- suggesting that this route of virus transmission bypasses the insect's anti-virus defence systems.” When mites inject the virus, “levels of this single virulent form can be 10,000 times higher than in the absence of Varroa." The researchers attribute the spread of virulent DMV to mite exposure. To read more, visit: http://www.sciencedaily.com/releases/2014/06/140626172742.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily+%28Latest+Science+News+--+ScienceDaily%29 .
“Honeybees in East Africa Resist Deadly Pathogens: Bees in Kenya stay healthy despite parasites and viruses that collapse U.S. and European hives”: 17 Apr 2014, National Geographic
Varroa mites were found among native African bees in Kenya in 2009, but according to a study just published in PLOSOne, the Kenyan bees – like the Africanized hybrids found in Central America and the U.S. southwest – seem resistant to them. These bees are also resistant to Nosema, just found in Kenyan colonies. Entomologist Elliud Muli, senior lecturer in the Department of Biological Sciences, South Eastern Kenya University, together with a Penn State research team, surveyed colonies in “all of Kenya's major ecosystems: savanna, mountains, tropical coast, and desert . . . measur[ing] the sizes of hives and the numbers of bees and test[ing] them for parasites and pesticide contaminants,” and reported amazement at the bees’ “resilience” despite the prevalence of both the mite and the microsporidian.
The researchers asked what could explain that resilience: genetics, or relative lack of management? If genetic, potentially selective breeding could help bees elsewhere. However, Kenya’s different farming practices may be responsible: “so far, African bees live relatively free of human input. The study found very low levels of just a few pesticides in Kenyan hives, when there were any at all. Beekeeping in Kenya is typically a small-scale family affair done for honey; most crop pollination still relies on wild colonies. Bees colonize hollow logs and keepers mostly leave them alone, as is the traditional way.” Kenyan bee colonies are not manipulated, rented out, or trucked for commercial pollination. The study argues that “Kenyan beekeepers . . . should copy Western practices as little as possible . . . and in particular refrain from treating them with pesticides even though Varroa and Nosema have crept in.”
Also, unlike western queen breeding practices, Kenyan queens come from “natural swarms.” The Penn State team says that "the wild Kenyan bees have their own resistance. . . It would be a mistake to mess with that." For Kenyan bees, “it's survival for the fittest, and mother nature seems to be getting it right . . . She's giving us a broad genetic pool of honeybees capable of dealing with any environmental shocks on their own."
To read more, visit: http://news.nationalgeographic.com/news/2014/04/140416-honeybees-africa-kenya-disease-nosema-varroa-resistance-genetics-pesticides/?rptregcta=reg_free_np&rptregcampaign=20131016_rw_membership_r1p_us_dr_w#close-modal
“Asian Hornet trap launched to Combat the Latest Honey Bee Pest in Europe” 5 Mar 2014, ABJ Ezine
The Asian Hornet (Vespa velutina), invaded Europe in 2004 via a pottery shipment from China to France: the spreading hornet population has since decimated honey bees in regions of France Belgium, Spain, Portugal, and Italy. First, hornets kill individual foragers as they return to their colony: the bees begin staying inside, then, weak from hunger, are invaded by a mass of hornets, which feed not only on bees, but hive food supplies. The hornets’ nests, high in trees, are hard to find until falling autumn leaves expose them, by which time they have already done their damage to bee colonies.
To control this threat, Vita Ltd. has released ApiShield, a non-chemical trap which capitalizes on the way these large, aggressive hornets attack hives. The ApiShield “lures hornets into a trap in the bottom of the beehive. The trap, which acts as a base for a hive, has a modified front entrance for the honey bees and decoy side entrances that attract the Asian hornet and other flying honey bee pests. The hornets try to enter the hive by the unguarded side entrances, but become trapped in the false bottom, and then dehydrate and die. The beekeeper simply removes the dead hornets as required.” To keep bees from entering the false bottom and side entrances, these are blocked when the trap base is set up. Once bees habituate to using the front entrance, the beekeeper can open the side entrances.
Not only Asian hornets, but also wasps and robber bees fall prey to this trap: they naturally avoid the honey bee-guarded front entrance and try to invade the “undefended decoy side entrances.” An additional advantage is that the false bottom can serve as a mite trap, as well. The trap has been tested in France and Greece and is now available “in hard-wearing pine wood; a polystyrene version is also planned for the near future.” To read more, visit: http://us1.campaign-archive1.com/?u=5fd2b1aa990e63193af2a573d&id=98732b6ca1&e=e9ff21e0bb
“RNAi Effects on non target organisms not understood”: 28 Jan 2014, The New York Times
To read more, visit: http://www.nytimes.com/2014/01/28/business/energy-environment/genetic-weapon-against-insects-raises-hope-and-fear-in-farming.html?hp
As reported in last month’s “bees in the news” column, new research has suggested that RNA-interference techniques show potential to silence genes of Varroa mites if a vector for delivery into honey bee hives can be found. The EPA commissioned a panel of leading scientists working in entomology around the U.S. to assess RNAi potentials and pitfalls. The panel reported that because “not all aspects of the fate of dsRNA in the environment and potential effects on nontarget organisms are necessarily understood,” caution is essential in field-testing RNAi techniques. However, in 2013, the EPA gave permission for a field test to study 20,000 acres of RNAI corn “to study the Snf7 gene directed at the corn root worm before ‘standardized methods for measuring and assessing the aforementioned hazards’ were developed.” The Scientific Advisory Panel noted that this approach directly contravenes the EPA’s stated goal of avoiding danger to non-target insects.
So far, the panel says, “it is unclear how RNAi technology can translocate throughout the environment, but possible transmission may include dust from degraded plant material, soil, plant pollen taken to bee hives, and even mammals consuming the plants and depositing the digested food far from the initial treatment area. The nontarget exposure opportunities present many concerns.” The panel notes that though RNAi technology may prove a useful tool, “uncertainties clearly exist with respect to a complete understanding of all current and future applications of this technology . . . The current testing paradigm for nontarget species characterizations, which emphasized limited dose testing and use of mortality as an endpoint, likely will not be adequate to assess adverse effects resulting from off-target gene silencing, silencing of the target gene in unintended organisms, immune stimulation, and saturation of the RNAi machinery in cells.”
The panel notes that where honey bees are concerned, “factors influencing the possibility of exposure by this pathway (e.g. longevity of dsRNA once consumed, concentration resulting within the herbivorous insect) are not known.” In particular, the panel noted that “as the Varroa is basically a virus-filled-syringe in the guise of an arachnid, using RNAi upon Varroa or in bees to get at Varroa will subject honey bees to unknown gene silencing.”
To read more, visit: http://home.ezezine.com/1636/1636-2014.02.13.10.56.archive.html
“Zombie Flies Infecting Major Media Outlets: May Be Cause of Media Collapse Disorder,” by Tom Theobald. 7 Feb 2014, Catch the Buzz Ezine
(Kim Flottum of Bee Culture passed along this “somewhat tongue in cheek” discussion of the zombie fly invasion: it was reproduced in LCBA’s March newsletter as a humorous prelude to LCBA’s March 2014 monthly meeting, where U.W. scientists presented results of their survey of the extent of these insects’ parasitism on honey bees in the Pacific Northwest.)
“The so-called "Zombie Flies" have supposedly reappeared in bee colonies and again are being insinuated as an explanation for the loss of millions of colonies of bees. Is there any merit to these bizarre and desperate reports? Unlikely.
“Properly known as the Phorid Fly, these predators have been seen in bee colonies occasionally for years and have always been thought of as incidental and of little consequence. But now? It isn't the new agricultural technologies killing bees, it is Zombie Flies, Zombie Flies carrying cell phones no doubt, how else are they able to alert the media?
“First, there is no evidence presented that these are anything other than occasional encounters, there has been no legitimate statistical sampling that I'm aware of, but this simple fact doesn't deter industry apologists and spin doctors grasping for straws in their never ending search for "sound science".
“There is a more likely explanation. The Phorid Fly depends on bumblebees as its primary host. Bumblebee populations have crashed for the same reasons as honey bees. In the absence of bumblebees these flies are struggling to survive, and what's left? Honey bees, of course, primarily because of beekeepers' efforts to keep the honey bee populations going.
“Zombie Flies? What really warrants our concern are Zombie Reporters at Zombie News Outlets.”
Original Tom Theobald piece: http://home.ezezine.com/1636/1636-2014.02.07.08.38.archive.html
“Genetic Weapon Against Insects Raises Hope and Fear in Farming”: 27 Jan 2014, The New York Times
The Varroa destructor mite’s genome was mapped several years ago: can we use that knowledge to stop mites from parasitizing bees? Scientists at the University of Kentucky have teamed up with Monsanto to disable Varroa mites’ genes through RNA interference. By releasing “gene-silencing agents,” “very target-specific,” they hope to avoid the toxicity and sublethal effects caused by pesticides and miticides.
How does RNA interference (RNAi) work? It’s “a natural phenomenon that is set off by double-stranded RNA. DNA, which is what genes are made of, is usually double stranded, the famous double helix. But RNA, which is a messenger in cells, usually consists of a single strand of chemical units representing the letters of the genetic code. So when a cell senses a double-stranded RNA, it acts as if it has encountered a virus. It activates a mechanism that silences any gene with a sequence corresponding to that in the double-stranded RNA. Scientists quickly learned that they could deactivate virtually any gene by synthesizing a snippet of double-stranded RNA with a matching sequence.”
Monsanto is seeking approval to use RNAi in corn to eradicate western crop rootworm. However, some scientists are concerned that other, beneficial insects could be affected by eating the corn or “become exposed to the RNA in soil or water.” This is what happened “when a double-stranded RNA intended to silence a rootworm gene also affected a gene in the ladybug, killing that beneficial insect.”
The National Honey Bee Advisory Board argues that “To attempt to use this technology at this current stage of understanding would be more naïve than our use of DDT in the 1950s.” The EPA is meeting during the first week of February “to discuss the potential risks of RNA interference.”
The Times reports that “Monsanto is also looking at putting RNA into sugar water fed to honeybees to protect them from the varroa mite. . . If the RNAi is directed at a genetic sequence unique to the mite, the bees would not be harmed by ingesting it, while the mites would be killed once they attacked the bees. One field trial showed that this technique could help protect bees from a virus. Monsanto acquired Beeologics, a company developing the RNAi technology for bees.”
“Bee Deaths May Stem From Virus, Study Says”: 21 Jan 2014, The New York Times
Much as influenza has jumped to people from chickens or pigs, USDA researchers have found evidence that the tobacco ringspot virus has jumped to honey bees via soy plants, and that infection by this virus is correlated with fall through winter bee die-offs as the virus attacks the bees’ nervous systems: “the share of bees infected with the virus rose to 22.5 percent in winter from 7 percent in the spring.” Bees are exposed to the virus via pollen; the virus is then spread to larvae via bee bread. Varroa mites, too, may play a role, spreading the virus by infesting larvae.
Tobacco ringspot virus – an RNA virus – is the first virus known to have made the leap from pollen to bees. Its “rapid mutation rate also allows RNA viruses to switch hosts more rapidly than conventional pathogens, with the tobacco virus jumping to bees,” as avian flu has moved from chickens to humans. Since “about 1 in 20 plant viruses is found in pollen, . . . pollen should be monitored as a potentially significant source of host-jumping infections,” according to the Beltsville, Maryland research group.
The Bee Culture ezine reports that bees may spread the virus from flower to flower as they forage, thus exposing other pollinators. Bee Culture gives added details on how Varroa mites resist the virus.
Invasive Asian Hornets Decimating Bees in France: May Be Moving Into Other Countries
After a “possible” sighting in south-eastern England, British beekeepers are keeping nervous watch for the “invasive and predatory” Asian hornet: Vespa velutina nigrithorax can be as much as four times bigger than a honey bee and packs a nasty sting. According to Britain’s Department for Food and Rural Affairs (DEFRA), "a handful of hornets can destroy an entire nest [of honey bees] in a couple of hours." After initial alarms in 2010 and 2011, concern was renewed this summer, after a Frenchman was stung to death when he stumbled upon an Asian hornet nest.
The VITA-Europe August 2013 blog reports: “Asian hornet nests are hard to spot until the leaves fall from their nesting trees in autumn. But the damage they do is unmistakable: groups of five to 50 hornets hover in front of a hive, picking off single honeybees, decapitating them and stripping off their wings and legs before making off with the ‘meat ball’ to their nest to feed their young. As the attacks continue, the honeybee colony stops flying and has to consume its own stores, eventually weakening it to such a point that an invasion force of many hornets enters the hive to rob it out.” DEFRA points out that since these hornets are also scavengers, if they invade a diseased bee colony, they can carry infections to the next colony they attack. The hornets are versatile at adapting to varied weather and thrive in urban as well as rural conditions.
First spotted in 2005, the hornets are thought to have come to France in a 2004 Chinese pottery shipment. DEFRA warns that “there is a ‘high possibility’ the hornets could be introduced via imported plants, flowers, garden items such as pots or furniture, timber or freight containers.” According to VITA-Europe, “By 2007 apiaries around Bordeaux were suffering up to 70% colony losses. Since then [the Asian hornet] has been spreading at a rate of about 100km each year into neighbouring countries,” including Italy, and has been projected to reach southern England “at some point.” DEFRA asks British beekeepers to report any potential sighting to their BeeBase website. The UK National Bee Unit characterized the August 2013 sighting as credible but has not been able to confirm it through field inspections. Meanwhile,Vita has designed a trap specifically for Asian hornets and is planning a test for the French market soon.
Further reading: “Bee-killing Asian hornets could be heading to Britain,” U.K. Metro, 5 Sep 2013, http://metro.co.uk/2013/09/05/bee-killing-asian-hornets-could-be-heading-to-britain-3951268/. For DEFRA’s risk assessment report, visit the 2011 article “Danger! The bee-killing Asian hornet is set to invade Britain,” The Guardian, 17 Oct 2011 and click on the link midway through: http://www.theguardian.com/environment/2011/oct/17/asian-hornet-bee-killer-invasion. For further details, including links to PDFs that compare/contrast Asian with other hornets, read “Asian Hornet alert,” 23 Aug 2013, VITA Blog, at: http://www.vita-europe.com/blog/asian-hornet-alert/.
“Scientists find genes that help bees defend against mites”: Scientists at Purdue are working to isolate specific genes that govern the trait called “Varroa sensitivity hygiene,” known to beekeepers as hygienic behavior. Starting from 1300 markers, they have isolated 27 genes and identified three leading candidate genes which govern bees’ sense of smell and may trigger behavior that leads bees to find and destroy Varroa-infested pupae, thereby interrupting the reproductive cycle of the mites. According to lead researcher Greg Hunt, “Bees are fighting back. They're getting rid of the mites themselves . . . We can select for these traits now, but it's tedious. If we can identify the genes that influence these traits, we could develop better methods to screen for these genes and speed the process." To read more, click here or visit: http://www.agprofessional.com/news/Scientists-find-genes-that-help-bees-defend-against-mites-177970541.html . To read a PDF file of the complete study online, click here or visit: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0047269
“Honey bees fight back against Varroa”: Honey bees have evolved proteins in their antennae to promote hygienic behavior, according to a recent study at the University of British Columbia. Damaged larvae release these proteins when Varroa destructor is present, and adult bees then engage in uncapping and removing parasitized larvae from brood comb. Since Varroa are becoming increasingly resistant to miticides, the researchers suggest that beekeepers selecting colonies based on concentrations of these proteins in their bees may be able to lessen Varroa infestations in their hives. For more information, read Phys.org’s account of the study: click here, or visit: http://phys.org/news/2012-09-honey-bees-varroa.html. The full study is available online at BioMed Central’s open access journal Genome Biology: click here or visit: http://genomebiology.com/content/pdf/gb-2012-13-9-r81.pdf.
“Vita helps fund new research to halt honey bee killer” describes how massive new grant funding has been made available to researchers in Aberdeen, Scotland, who are seeking to build on 2010 research that mapped the genome of the Varroa destructor mite itself. It may prove possible to “silence” specific genes in the mite. Work is now underway to isolate genes that might – ideally – stop Varroa from successfully attaching themselves phoretically to adult bees or from infesting larvae. For more information, click here or visit: http://www.vita-europe.com/new-money-for-research-to-halt-honey-bee-killer/ .For a BBC News report on the original study, click here or visit: http://news.bbc.co.uk/earth/hi/earth_news/newsid_9306000/9306572.stm
“Host adaptations reduce the reproductive success of Varroa destructor in two distinct European honey bee populations”:
At our LCBA meetings, we’ve often discussed whether it’s better to treat for mites and other threats to bees, or to let the bees adapt, to “breed a better bee.” A paper published in Ecology and Evolution (2012; 2(6), 1144-1150) suggests that beekeepers’ efforts to control mites can actually be harmful. It’s true that heavy mite loads open the door to viruses that kill colonies. However, this study found that “a few subpopulations in Europe have survived mite infestation for extended periods of over 10 years without management by beekeepers and offer the possibility to study their natural host–parasite coevolution.” In colonies studied in France and Sweden, bees “evolved resistant traits that reduce the fitness of the mite (measured as the reproductive success)” by about 30%. As an apparent result of reducing mite populations, the colony was able “to evade the development of overt viral infections.” To read more, click here, or visit: http://onlinelibrary.wiley.com/doi/10.1002/ece3.248/pdf.
“Honey-bees found to have bite that stuns,” BBC News, Oct. 26 2012: Biologists in Greece have discovered that honey bees actually bite pests like Varroa mites and wax moths, which are too small for bees to sting. When bees bite, they secrete a chemical called 2-heptanone which stuns these pests, giving the bees a window of opportunity to kick the mites or moths out of the hive. 2-heptanone is now being studied for possible use as a local anaesthetic for human beings. For more information, click here. Complete URL: http://www.bbc.co.uk/news/technology-20080389. To read the complete research study, "The Bite of the Honeybee: 2-Heptanone Secreted from Honeybee Mandibles during a Bite Acts as a Local Anaesthetic in Insects and Mammals," click here.
"'Zombie' Bees Electronically Enhanced to Help Solve Die-Off Mystery”:
On Sept. 12, 2012, National Geographic News reported that entomologists are equipping bees parasitized by zombie flies with bee-sized radio trackers. John Hafernik of San Francisco State University speculates that as parasitized bees leave hives to cluster around outdoor lights, they may be “‘committing altruistic suicide’ to protect their hive mates.” Another possibility: zombie flies may be “mind-controlling” bees, making them fly at night. Though Hafernik doubts that zombie flies have anything to do with colony collapse disorder, he hopes that tracking the bees "could shed light on the mechanism behind abandonment." For more information, click here. Complete URL: http://news.nationalgeographic.com/news/2012/09/120912-zombie-bees-tagged-science-zombies-zombees/. For more news about zombie flies and their parasitism of honey bees, scroll down. . . .
More News about 'Zombie Bees':
OSU entomologist Ramesh Sagili suggests that zombie fly parasitism may not be new - but that since we preserve bee specimens in alcohol, flies' larvae would be killed before they could be discovered. If you think your bees have zombie fly parasites, Sagili suggests "placing the bees in a jar with multiple layers of cheesecloth secured over the top with a rubber band to let in air," then watching for the fly maggots to appear. For more information, click here; complete URL,
State's First Case of 'Zombie Bees' Reported in Kent
On Sept 23, 2012, the Seattle Times reported Washington State's first known case of zombie fly parasitism on honey bees. Zombie flies inject their eggs into bees' abdomens, where their young grow to maturity, feeding on the host bee's internal organs. Affected bees display bizarre (for honey bees) behavior, including night flying. To read more, click here. Complete URL:
Worried that zombie flies may be parasitizing your bees? Check San Francisco State University biologist John Hafernik's website, ZombeeWatch.org.
Above, image of Varroa Mite supplied by Kika De La Garza Subtropical Agricultural Research Center Weslaco, Texas, USA.
Above, visible as a dark, oval shape, an adult female varroa mite feeds on the midsection of a developing worker bee. Adult female varroa mite. by Scott Bauer: Image Number K8536-1 from http://www.ars.usda.gov/is/graphics/photos/
Above, Honeybees [with visible phoretic varroa mites] by Brad Smith, Flickr, 28 March 2006 (for Creative Commons license, click here).
Below, microscopic view, tracheal mites (Wikimedia Commons):
Feral Bees, Centralia, Washington: could these healthy-looking bees be pathogen reservoirs? Food for thought. (photo, Susanne Weil)
Above, HopGuard strip on frame (photo by Randy Oliver); below, a pair of Varroa mites in the lab (image courtesy of Vita Gallery, Vita Europe Ltd.).
Below, Varroa mite on a bee's eye (image from Vita Gallery, Vita Europe Ltd):
Below, image of Varroa Mite on honeybee pupa supplied by Kika De La Garza Subtropical Agricultural Research Center Weslaco, Texas, USA (found on Wikimedia Commons):