Scitech | What’s all the buzz about?

Bee population in steady decline

Imagine yourself lying in the wilderness. A cool breeze brushes against the trees, the sun rises above the horizon, and the birds begin to sing their song. All of a sudden, a whirring sound dawns upon you and seizes you out of a dream. Within a patch of blooming daisies is a buzzing honey bee, busy at work helping maintain nature’s harmony.

The real nightmare – much realer than being stung by a bee – is the silence that sets in after those whirring sounds fail to reappear. While the daisy ceases to flower, a multitude of other plants – many of which are vital to our own food security – also begin to suffer. Staple crops such as wheat, corn, rice and soybeans require pollination to grow, and bees are arguably the leading insects in this role.

Over the past ten years however, honey bees have been in steady decline across North America and in Europe. In Canada, national bee colony losses over the winter increased from a historical average of 10 to 15 per cent to 35 per cent in 2008, and then ranging from 15 to 29 per cent between 2009 and 2014, according to Health Canada. Although the parasitic mite “V. destructor” is the biggest detriment to the survival of the species today, the exact explanation to the bee crisis varies by location and involves a combination of other issues, including environmental management practices and a quickly changing habitat.

Bees spend most of their on to ten month lifespan gathering nectar and pollen. They attract pollen with the electrostatic force generated by their hair. The hair on the legs of a bee is particularly stiff, allowing the bee to groom the pollen into pockets on its body until it has returned to its nest. Through such foraging activity, pollen gets redistributed across the ecosystem and transferred from the male part – the anther, to the female part – the stigma, of a flower of the same species, in a process called pollination. This results in the fertilization of the flower and the growth of seeds and fruits. The plant has produced offspring and the cycle of life is perpetuated.

As world population and the global demand for food continue to grow, the act of pollination is tightly intertwined with our own food security. Between 1961 and 2006, the dependence of the agricultural industry on pollinators in the developed world increased by 50 per cent between 1961 and 2006, and an extra 10 per cent in the developing world. In the face of this development, recent bee colony losses are forcing us to ask ourselves some difficult questions.

The V. Destructor mite must harbour in a bee colony to reproduce. It latches on the body of the bee and sucks its hemolyph – the equivalent of blood in vertebrates. Without treatment, the bee begins to show disease symptoms such as malnourishment, weight loss, and saddest of all, the inability to fly. The German Bee Monitoring Project – one of the most significant experiments on honey bee colony health – studied more than 1200 colonies from 120 apiaries over a four year period and found a clear link between high varroa mite levels and the deformed wing (DWV) and acute bee paralysis viruses (ABPV), as well as reduced lifespan of the queen and weakness of colonies in autumn.

As world population and the global demand for food continue to grow, the act of pollination is tightly intertwined with our own food security.

Professional Canadian apiculturists identify resistance to acaricides – chemical substances poisonous to mites – as being the main cause of mortality among honey bee colonies – most common among these synthetic compound is fluvalinate, which is commercially known as Apistan. This belief among the community is reflected in research published by the Journal of Apiculture in 2008: “The level of infestation of varroa mites that cause colony damage appears to have decreased over time.” They go on to say, “in the early 1980s, in Europe, a bee colony could harbor several thousand mites without dramatic symptoms. Today, a fall infestation rate of 10 per cent, corresponding to about one thousand mites in a colony of 10,000 bees, is considered to be a critical threshold for winter survival of the colony.” Attempts to control the pest since it was first recognized have surely been in the best interest, but the fact remains that the threat of the Destructor has evolved greatly during this time.

The growing number of extreme weather events across the globe puts unforeseen stress on colonies, both directly and indirectly.

Solutions to the pesticide resistance of Varroa mites have been explored – such as selectively breeding the honey bees who are resistant to the pathogen or creating non-chemical control methods, but some aspects of honey bee colony loss are inextricably tied to larger environmental and social questions.

The growing number of extreme weather events across the globe puts unforeseen stress on colonies, both directly and indirectly. A lack of precipitation, or an inconsistency in rainfall patterns, reduces nectar production, which in turn can seriously limit honey bee activity. Moreover, when the temperature reaches unusually cold levels, the honeycomb brood – the beeswax structure of cells where the queen bee lays eggs – is chilled, and while some bees become more susceptible to pathogens in the long-term, others die immediately. On the flip side, warm and humid weather helps sustain pathogen loads in a honey bee colony and foster disease.

Increased international trade over the last several decades has presented additional challenges to honey bee populations – as it has for many other organisms caught in the web of globalization. The Varroa mite migrated from its original host, the East Asian bee Apis cerana to A. mellifera colonies imported to East Asia, and since then, they have spread across the globe. Small producers used to be the bread-and-butter of the apicultural industry, but in today’s changing landscape, the competition is tilted in favor of industrial-scale apiaries, who simply have more resources in dealing with adversity.

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