Why are all the bees dying?

HoneyBee Why are all the bees dying?

Photo by Erik Hooymans

Bees are great. They have an amazing social hierarchy, they provide medical care for their sick, they have ruthless security ‘bouncer-bees’ and each bee travels huge distances to gather about one twelfth of a teaspoonful of honey. For us humans, the benefits of bees don’t stop at honey. About a third of our crops – approximately $220 billion-worth globally – are inadvertently pollinated by foraging bees and, from what I’ve heard, we really don’t want to have to start doing that ourselves.

The problem is that bees are dying at an alarming rate. As it happens, my father is a budding bee-keeper and has just received a letter from the Food and Environment Research Agency that reports a halving of honey production in South-East England in the last six years alone. This problem is, however, happening all over the world. Imaginatively dubbed ‘colony collapse disorder’ (CCD), a mystery disease is wiping out huge numbers of bees yet no one can pin down exactly what the cause is. There are several theories, so I’ve taken the liberty of making a list akin to a ‘Top Six Most Wanted Villains’ of the bee world.

Varroa destructor on honeybee host Why are all the bees dying?

A varroa mite feeding on a honeybee (Wikicommons)

Varroa mites: Affectionately known as ‘vampire’ mites, these teeny-weeny bugs are big trouble. They suck hemolymph (the bee’s version of blood) from honeybees and, in so doing, weaken the bee and may even transmit deadly viruses (more later).

Neonicotinoids and other pesticides – Neonicotinoids (NNs) are chemicals designed to kill insects that feed on farmed crops. They bind to acetylcholine receptors on the cells of the insect’s nervous system, eventually blocking their normal use, causing paralysis and death. In the past couple of years, various research groups have shown that these chemicals get into bee hives at dangerous, though not lethal concentrations. Not only that, but a paper published in Nature showed that a cocktail of these chemicals may lead to CCD by affecting bee behaviour, presumably through their effects on the bees’ brains. Bees affected by these chemicals tend to forget where they are in relation to the hive, and produce less food. Other research has shown that NNs may affect the way that bees metabolise their food to produce energy. Scientists have even shown that exposure to NNs affects an important immune defence pathway, which may make bees more vulnerable to parasites and viruses.

Viruses: Viruses such as Israeli acute paralysis virus, deformed wing virus and acute bee paralysis virus are spread by varroa mites and have all been identified as possible causes of CCD. Deformed wing virus is particularly tragic; if pupae are infected and develop wing deformities, they are kicked out of the colony, and the number of healthy bees dwindles. Israeli acute paralysis virus has been shown to interfere with the bees’ cellular machinery that produce proteins.

Nosema – this is a fungus that causes intense diarrhoea when swallowed by a bee, leading to worker bees pulling a sickie, which means less food for the hive. To add insult to injury, the queen bee becomes infertile and the colony stops producing young.

Malnutrition – Bees that collect their food from a variety of sources tend to be more hardy and resistant to infection than those that rely on only one or two types of flowering plant. In the US where farms cultivating one or two crops such as wheat or corn are vast, bees may become malnourished and more susceptible to disease.

Female Apocephalus borealis ovipositing into the abdomen of a worker honey bee Why are all the bees dying?

Female phorid fly laying eggs into a worker honey bee. Core A, Runckel C, Ivers J, Quock C, Siapno T, et al. (2012).

Parasitic phorid fly – Last year, a researcher found a phorid fly larva in a test tube containing a honeybee that had died from suspected CCD. Phorid flies (which apparently scuttle more than they fly) lay eggs on the bee’s abdomen, which then hatch and feed on the bee. Weirdly, bees that carry this parasite end up acting more like moths than bees (foraging at night, buzzing around bright lights) before abandoning the hive.

What’s most likely is that CCD is caused by a mixture of two or more of the culprits mentioned above working in tandem. For example, varroa mites weaken bees and give them viruses. While a colony may be able to withstand either the mites or the virus, the two knocks together could be lethal. This interplay between several different factors makes it all the more difficult for scientists and beekeepers to research and prevent CCD.

So what’s being done to stop all the bees dying? Aside from all the tried and tested treatments for the parasites and viruses known, there are new efforts to save the bees via various industrial collaborations. Earlier this year, Monsanto set up its own Honey Bee Advisory Council including scientists, beekeepers, industrial and governmental representatives to try and tackle the issue. In 2011, Monsanto also bought Beeologics, a company in Israel that researches possible solutions to CCD. One strategy used by Beeologics against bad viruses is to deliberately infect bees with a special artificial ‘good’ virus. In turn, this good virus infects any varroa mites feeding on the bee. Amazingly, this good virus acts to prevent the mites from being able to pass on bad viruses to the bee. This treatment is currently passing through regulatory tests, but it will hopefully represent the start of a new approach to keeping bees alive for the benefit of humanity – and not just for the honey.

Post by Natasha Bray

button print gry20 Why are all the bees dying?

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