Tuesday, 1 February 2011

SOS: Save our Science - Bug Battle

ResearchBlogging.orgThis post was a request from a reader (Yay!). I've got a lot of different projects going on at the moment so have been a bit slow with the posting. Hopefully I'll be posting about my latest lab soon. There's still a lot to write when I get the time. We had a lot of fun last week meeting the students interviewing to join my course next year and the lab work is going well. There is a much more theoretical element to it, which I've been enjoying. Anyway, so this is a bit of a proto-story really. A possible explanation for the disappearance of bees worldwide; though the real science is still under wraps.
A honeybee (Apis mellifera) (source)

Pollinating insects, like bees, are disappearing across the world. The phenomenon is known as colony collapse disorder (CCD). If CCD continues as it is the world stands to lose most, if not all, pollinating species, which stands to rapidly wipe out all flowering plant species and would severely alter every land based ecosystem. A key element in understanding CCD was uncovered over two years ago, but is only just emerging as published work.

CCD is being studied by a dedicated group of researchers in the US Department of Agriculture’s Bee Research Lab. The rapid decline in colonies of pollinating insects due to CCD was originally observed in the US but has since been identified around the globe, though it has yet to arrive in some countries, including the UK.

Pollinating insects are “good insects” they aid plant reproduction by carrying pollen between flowers and do not cause damage to crops. Farmers try very hard to protect or even encourage these species whilst eliminating pest species, such as aphids, which attack the roots, leaves and stems of plants. Bees are a key example of pollinating insects which live in colonies, where thousands of individuals live and work together. Different bees perform different jobs allowing the colony to work more efficiently as a whole. CCD can wipe out entire colonies extremely rapidly.

As with many environmental disasters in recent years, it appears to all link back to humans. Much of the latest research indicates that chemical pesticides used in farming may be damaging these insects. Manufacturers are required to test the effects of their pesticides on “non-target” species (pollinators). As with many cases of science in industry, many question the validity of these tests and claim that more needs to be done. They also generally cover the bare minimum of requirements and fail to consider possible secondary effects. The damage cause by this has been observed several times throughout history, most especially the use of DDT in the 60s, which inadvertently killed many top predators. Tests show that neonicotinoid pesticides do not affect bees, however little is done to assess secondary effects.

Successful crops depend on pollinating insects (source)

Neonicotinoids are the current pesticides of choice in many western countries, over 2.5M acres in the UK were treated with them in 2008. The favourite is Imidacloprid, with £520m spent on it in 2009 alone. These drugs spread through treated plants and can be transmitted to pollinating insects. The normal dose of a neonicotinoid to a healthy bee is reported to have little effect. However if a bee is previously weakened it can have serious effects on the tolerance of pesticides.

The team investigated a common bee illness called nosema in association with pesticide exposure. Nosema can spread rapidly though bees, it is a parasite, draining a hosts energy and so driving up its need for food. It also affects immune responses. There is little effect on the immune system of an individual bee. However, animals which live close together in a colony have evolved colony immunity, where individuals show behaviour which prevents others from getting ill. Primarily, workers produce antiseptics which are used to prevent infection of food stores. Nosema suppresses this ability. The findings of the study are reported to show that even a low dose of neonicotinoids strongly accentuates nosema’s effects, leading to rapid spread of illness through a colony.

However, if this is true, why has CCD yet to be reported in the UK, when neonicotinoid pesticides are being used so widely on our crops? Also, what effects may the same low dose of pesticides have on humans? They are currently shown to be safe, but the data from bees show that an undetectable level of pesticide can have a strong effect in the correct situation.

Bees working together in a colony (source)

Similar findings have already been published by a French group, however the US findings have been delayed for nearly two years. Their data has remained unpublished and unnoticed because journals perform rigorous cross-examination of submitted data. This is the foundation of the modern scientific community, but has been under a lot of scrutiny as to its relevance in the 21st century. Publication is widely considered a distinct validation of findings; a seal of approval. However not all printed data is good science, and conversely sometimes important information is delayed, when it is urgently needed.

Until this study appears in print it is impossible to judge whether peer-review has been delaying this vital information or if it has saved us from an embarrassing scientific farce of poor data and weak evidence.
A study such as this is likely to attract a lot of attention; manufacturers, farmers, governments, environmentalists and consumers will all be interested to know the outcome and are sure to have very different responses, which are likely to lead to extensive debate over how we are to proceed. This is certainly an important story for all of us and the way we handle it is certain to have significant effects on our future.

Alaux, C., Brunet, J., Dussaubat, C., Mondet, F., Tchamitchan, S., Cousin, M., Brillard, J., Baldy, A., Belzunces, L., & Le Conte, Y. (2010). Interactions between microspores and a neonicotinoid weaken honeybees Environmental Microbiology, 12 (3), 774-782 DOI: 10.1111/j.1462-2920.2009.02123.x

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