POSTED: 8 JUNE 2007 8:00am HST

Fungi and pesticides act together on bees

Parasitic Fungi and Pesticides
Act Synergistically to Kill Honeybees?

by Prof. Joe Cummins in Issue #34 Summer 2007 of ISIS Science in Society

The Insitiute of Science in Society presents evidence that parasitic fungi can kill insects when low, otherwise non-lethal concentrations of pesticides are present.

Honeybees are facing an unparalleled threat from something that’s causing them to leave their hives, never to return. Scientists call it “colony collapse disorder” (CCD) (Mystery of Disappearing Honeybees, SiS #34). The major suspects in the murder of honeybees appear to be systemic insecticides (the neonicotinoid systemic pesticides used worldwide to treat seeds and crops), including genetically modified (GM) crops (Requiem for the Honeybee, SiS #34), parasitic fungi (Parasitic Fungus and Honeybee Decline SiS 35), and radiation associated with wireless phones (Mobile Phones and Vanishing Bees, SiS #34).

It is unlikely, however, that the suspects act independently of one another, and there is evidence suggesting that parasitic fungi and pesticides interact synergistically in killing honeybees.

Fungi for biocontrol enhanced by sublethal levels of pesticide

Parasitic fungi are used extensively as biocontrol agents. Fungal spores are applied in sprays or baits, and it has been observed that the parasites frequently interact synergistically with neonicotinoid pesticides, particularly imidacloprid, in killing insects. When the spores are delivered as a suspension together with low, non-lethal levels of the pesticide, the insect-killing activity of the fungal spores is significantly enhanced. The spores of Beauveria bassinia used to treat the brown leafhopper rice pest, when accompanied by a sublethal dose of imidacloprid, killed the pest earlier and in larger numbers.

The fungus Lecanicillium muscarium in sublethal levels of imidacloprid gave satisfactory control of the sweet potato whitefly, and merited inclusion in integrated control programmes. Beauveria bassinia spores combined with imidacloprid at a level one tenth the lethal dose was found to significantly enhance control of the leaf cutting ant. Similarly, termites were controlled by imidacloprid at sub-lethal levels that enhanced the killing activity of the fungal parasite Metarhizium anisopliae. The presence of the insecticides at sub-lethal level appears to interfere with the insect’s immune system, making the insect more susceptible to fungal pathogens.

The neonicotinoid insecticides used to dress seeds are systematic, and accumulate in plant parts including the flowers. Hence honeybees collecting pollen will become exposed to the pesticide, and become more susceptible to fungal pathogens. The parasitic fungus, Nosema ceranae, a single celled parasite was indeed found in CCD-affected bee hives from around the USA.

Nosema locustae has been a commercial biocontrol fungus to control locusts and grasshoppers. An integrated pest management strategy with an emphasis on the use of Metarhizium, an ascosporic fungus, incorporates low levels chemical pesticides with additional biological options such as the microsporidian Nosema locustae and the hymenopteran egg parasitoids Scelio spp. . Nosema bombycis has been a major pest of the silkworm but it has been used to control Diamondback moth. Another microporidian, Vairimorpha sp., isolated from the Diamondback moth in Malaysia caused 100 percent mortality when applied to moth larvae at 1500 spores per larva. Nosema pyrausta infects the European corn borer and can be used in biocontrol of the pest.

Parasitic fungi increases the killing power of Bt biopesticide
Evidence implicating Bt biopesticides from GM crops has also emerged. Purified Bacillus thuringiensis Cry1Ab toxin was fed to Nosema infected and uninfected borer larvae. Nosema infection reduced the lethal dose of Cry1Ab toxin to one third the lethal dose of the uninfected larvae [11]. When Bacillus thuringiensis kurstaki (Dipel) formulations were used to treat Nosema pyrausta infected and uninfected corn borer larvae. The infected larvae had a lethal dose 45 times lower than the uninfected larvae.

I am not suggesting that biocontrol agents pose a threat to the honeybee, rather, the exposure to sub-lethal levels of systemic insecticides used in seed treatment of both conventional and GM crops and in widespread soil and foliar applications can affect beneficial insects by reducing their immunity to parasitic fungi. Furthermore, bees that otherwise are unaffected by exposure to Bt toxins in GM crops may succumb much more readily when they are infected with parasitic fungi, as reported in an experiment carried out at the University of Jena, Germany.

Tests have been carried out on one agent at a time
Regulators have allowed extensive deployment of systemic insecticides for seed treatment and they have allowed extensive use of foliar sprays of the systemic insecticides on a wide array of food and feed crops. The impact of such pesticides on honeybees has been evaluated using measurements of lethal dose of the pesticides alone, ignoring the clear evidence that sub-lethal doses of the insecticides act synergistically with fungal parasites of the insects. The honeybees may be falling victim to “friendly fire” directed to exterminating insect pests. Unfortunately, regulators around the world have dealt with decline of honeybees through tunnel vision, ignoring well-established pesticide-fungal parasite interactions. It is time for the regulators to wake up and impose a ban on the systemic pesticides before more bees succumb.

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Co-operating culprits



POSTED: 29 APRIL 2007 9:00pm HST

What is destroying bees across the world?

bee pollinating a sunflower by Paul D. Haemig

[Editor's Note: The fact is nobody really has a handle on why bee colonies are collapsing across the world. Two theories are reported on below.]

Are Genetically Modofied Crops Killing Bees?
by Gunther Latsch on 22 April 2007 in Der Spiegel

A mysterious decimation of bee populations has German beekeepers worried, while a similar phenomenon in the United States is gradually assuming catastrophic proportions. The consequences for agriculture and the economy could be enormous.

Is the mysterous decimation of bee populations in the US and Germany a result of GM crops?

Walter Haefeker is a man who is used to painting grim scenarios. He sits on the board of directors of the German Beekeepers Association (DBIB) and is vice president of the European Professional Beekeepers Association. And because griping is part of a lobbyist's trade, it is practically his professional duty to warn that "the very existence of beekeeping is at stake."

The problem, says Haefeker, has a number of causes, one being the varroa mite, introduced from Asia, and another is the widespread practice in agriculture of spraying wildflowers with herbicides and practicing monoculture. Another possible cause, according to Haefeker, is the controversial and growing use of genetic engineering in agriculture.

As far back as 2005, Haefeker ended an article he contributed to the journal Der Kritischer Agrarbericht (Critical Agricultural Report) with an Albert Einstein quote:

"If the bee disappeared off the surface of the globe then man would only have four years of life left. No more bees, no more pollination, no more plants, no more animals, no more man."

Mysterious events in recent months have suddenly made Einstein's apocalyptic vision seem all the more topical. For unknown reasons, bee populations throughout Germany are disappearing -- something that is so far only harming beekeepers. But the situation is different in the United States, where bees are dying in such dramatic numbers that the economic consequences could soon be dire. No one knows what is causing the bees to perish, but some experts believe that the large-scale use of genetically modified plants in the US could be a factor.

Felix Kriechbaum, an official with a regional beekeepers' association in Bavaria, recently reported a decline of almost 12 percent in local bee populations. When "bee populations disappear without a trace," says Kriechbaum, it is difficult to investigate the causes, because "most bees don't die in the beehive." There are many diseases that can cause bees to lose their sense of orientation so they can no longer find their way back to their hives.

Manfred Hederer, the president of the German Beekeepers Association, almost simultaneously reported a 25 percent drop in bee populations throughout Germany. In isolated cases, says Hederer, declines of up to 80 percent have been reported. He speculates that "a particular toxin, some agent with which we are not familiar," is killing the bees.

Politicians, until now, have shown little concern for such warnings or the woes of beekeepers. Although apiarists have been given a chance to make their case -- for example in the run-up to the German cabinet's approval of a genetic engineering policy document by Minister of Agriculture Horst Seehofer in February -- their complaints are still largely ignored.

Even when beekeepers actually go to court, as they recently did in a joint effort with the German chapter of the organic farming organization Demeter International and other groups to oppose the use of genetically modified corn plants, they can only dream of the sort of media attention environmental organizations like Greenpeace attract with their protests at test sites.

But that could soon change. Since last November, the US has seen a decline in bee populations so dramatic that it eclipses all previous incidences of mass mortality. Beekeepers on the east coast of the United States complain that they have lost more than 70 percent of their stock since late last year, while the west coast has seen a decline of up to 60 percent.

In an article in its business section in late February, the New York Times calculated the damage US agriculture would suffer if bees died out. Experts at Cornell University in upstate New York have estimated the value bees generate -- by pollinating fruit and vegetable plants, almond trees and animal feed like clover -- at more than $14 billion.

Scientists call the mysterious phenomenon "Colony Collapse Disorder" (CCD), and it is fast turning into a national catastrophe of sorts. A number of universities and government agencies have formed a "CCD Working Group" to search for the causes of the calamity, but have so far come up empty-handed. But, like Dennis vanEngelsdorp, an apiarist with the Pennsylvania Department of Agriculture, they are already referring to the problem as a potential "AIDS for the bee industry."

One thing is certain: Millions of bees have simply vanished. In most cases, all that's left in the hives are the doomed offspring. But dead bees are nowhere to be found -- neither in nor anywhere close to the hives. Diana Cox-Foster, a member of the CCD Working Group, told The Independent that researchers were "extremely alarmed," adding that the crisis "has the potential to devastate the US beekeeping industry."

It is particularly worrisome, she said, that the bees' death is accompanied by a set of symptoms "which does not seem to match anything in the literature."
In many cases, scientists have found evidence of almost all known bee viruses in the few surviving bees found in the hives after most have disappeared. Some had five or six infections at the same time and were infested with fungi -- a sign, experts say, that the insects' immune system may have collapsed.

The scientists are also surprised that bees and other insects usually leave the abandoned hives untouched. Nearby bee populations or parasites would normally raid the honey and pollen stores of colonies that have died for other reasons, such as excessive winter cold. "This suggests that there is something toxic in the colony itself which is repelling them," says Cox-Foster.

Walter Haefeker, the German beekeeping official, speculates that "besides a number of other factors," the fact that genetically modified, insect-resistant plants are now used in 40 percent of cornfields in the United States could be playing a role. The figure is much lower in Germany -- only 0.06 percent -- and most of that occurs in the eastern states of Mecklenburg-Western Pomerania and Brandenburg. Haefeker recently sent a researcher at the CCD Working Group some data from a bee study that he has long felt shows a possible connection between genetic engineering and diseases in bees.

The study in question is a small research project conducted at the University of Jena from 2001 to 2004. The researchers examined the effects of pollen from a genetically modified maize variant called "Bt corn" on bees. A gene from a soil bacterium had been inserted into the corn that enabled the plant to produce an agent that is toxic to insect pests. The study concluded that there was no evidence of a "toxic effect of Bt corn on healthy honeybee populations." But when, by sheer chance, the bees used in the experiments were infested with a parasite, something eerie happened. According to the Jena study, a "significantly stronger decline in the number of bees" occurred among the insects that had been fed a highly concentrated Bt poison feed.

According to Hans-Hinrich Kaatz, a professor at the University of Halle in eastern Germany and the director of the study, the bacterial toxin in the genetically modified corn may have "altered the surface of the bee's intestines, sufficiently weakening the bees to allow the parasites to gain entry -- or perhaps it was the other way around. We don't know."

Of course, the concentration of the toxin was ten times higher in the experiments than in normal Bt corn pollen. In addition, the bee feed was administered over a relatively lengthy six-week period.

Kaatz would have preferred to continue studying the phenomenon but lacked the necessary funding. "Those who have the money are not interested in this sort of research," says the professor, "and those who are interested don't have the money."

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Are mobile phones wiping out our bees?

by Geoffrey Lean & Harriet Shawcross
on 15 April 2007 in The Independent

Some scientists claim radiation from handsets are to blame for mysterious 'colony collapse' of bees.

It seems like the plot of a particularly far-fetched horror film. But some scientists suggest that our love of the mobile phone could cause massive food shortages, as the world's harvests fail.

They are putting forward the theory that radiation given off by mobile phones and other hi-tech gadgets is a possible answer to one of the more bizarre mysteries ever to happen in the natural world - the abrupt disappearance of the bees that pollinate crops. Late last week, some bee-keepers claimed that the phenomenon - which started in the US, then spread to continental Europe - was beginning to hit Britain as well.

The theory is that radiation from mobile phones interferes with bees' navigation systems, preventing the famously homeloving species from finding their way back to their hives. Improbable as it may seem, there is now evidence to back this up.
Colony Collapse Disorder (CCD) occurs when a hive's inhabitants suddenly disappear, leaving only queens, eggs and a few immature workers, like so many apian Mary Celestes. The vanished bees are never found, but thought to die singly far from home. The parasites, wildlife and other bees that normally raid the honey and pollen left behind when a colony dies, refuse to go anywhere near the abandoned hives.

The alarm was first sounded last autumn, but has now hit half of all American states. The West Coast is thought to have lost 60 per cent of its commercial bee population, with 70 per cent missing on the East Coast.

CCD has since spread to Germany, Switzerland, Spain, Portugal, Italy and Greece. And last week John Chapple, one of London's biggest bee-keepers, announced that 23 of his 40 hives have been abruptly abandoned.

Other apiarists have recorded losses in Scotland, Wales and north-west England, but the Department of the Environment, Food and Rural Affairs insisted: "There is absolutely no evidence of CCD in the UK."

The implications of the spread are alarming. Most of the world's crops depend on pollination by bees. Albert Einstein once said that if the bees disappeared, "man would have only four years of life left".

No one knows why it is happening. Theories involving mites, pesticides, global warming and GM crops have been proposed, but all have drawbacks.

German research has long shown that bees' behaviour changes near power lines.
Now a limited study at Landau University has found that bees refuse to return to their hives when mobile phones are placed nearby. Dr Jochen Kuhn, who carried it out, said this could provide a "hint" to a possible cause.

Dr George Carlo, who headed a massive study by the US government and mobile phone industry of hazards from mobiles in the Nineties, said: "I am convinced the possibility is real."

Evidence of dangers to people from mobile phones is increasing. But proof is still lacking, largely because many of the biggest perils, such as cancer, take decades to show up.

Most research on cancer has so far proved inconclusive. But an official Finnish study found that people who used the phones for more than 10 years were 40 per cent more likely to get a brain tumour on the same side as they held the handset.

Equally alarming, blue-chip Swedish research revealed that radiation from mobile phones killed off brain cells, suggesting that today's teenagers could go senile in the prime of their lives.

Studies in India and the US have raised the possibility that men who use mobile phones heavily have reduced sperm counts. And, more prosaically, doctors have identified the condition of "text thumb", a form of RSI from constant texting.
Professor Sir William Stewart, who has headed two official inquiries, warned that children under eight should not use mobiles and made a series of safety recommendations, largely ignored by ministers.