Story of the Vanishing Pollinators: Honey Bees
By Dr. Priyadarshini Chakrabarti (Basu) (Post Doctoral Researcher, Oregon State University, USA)
Pollination – a fascinating natural process of transferring pollens to stigma of flowers – is the principle reason behind crop production. This priceless ecosystem service provided by all pollinators is the reason behind food being served on our plates!
Honey bees are an essential component of agriculture and many crops are completely dependent on the pollination services provided by bees, often over a period as short as a few days. Bee pollination is essential for the production of a variety of agricultural and horticultural crops. Honey beeis economically important for its additional role in production of marketable products like honey and wax. Honey bees also play an important role in the maintenance of biodiversity through the pollination of wild flowers and these in turn provide a source for food for many small mammal and birdspecies, either through herbivory or by providing prey.
In recent decades, intensive agricultural practices have led to habitat destruction and increased pesticide use, resulting in a significant reduction in both the numbers and species diversity of wild bees and other beneficial insects. In 2007, India alone contributed approximately 21761.19 tonnes in pesticide usage out of 106210.92 tonnes among 21 Asian nations (FAO stat).
Pesticides have become an indispensable yet hazardous part of modern agriculture. Honeybee is extraordinarily sensitive to a range of chemical insecticides. Foraging bees may encounter lethal insecticide levels when pollinating agricultural fields or foraging in residential settings and further mortality can occur when contaminated nectar and pollen are brought back to the hive.
Pesticide exposure can have direct effects on individual bees as well as indirect effects on entire colonies. Studies in UK and other parts of the Western world have listed pesticides and systemic insecticides as the major reasons for colony collapse disorder in managed and wild colonies (apart from Varroa mites and Nosema fungus infection).
Pesticides used in field have been found to affect bees’ ability to navigate to the hive (homing), their power of learning and memory and also their orientation. This immensely hampers a bee’s capability to forage for food, find its way back home and hence – even more crucially – bee survival! Studies have indicated that queen loss and forager bee loss as a result of indiscriminate pesticide use have also affected colony growth and numbers. Several classes of pesticides such as neonicotinoids, carbamates and organochlorines vary in their methods of affecting bee biological systems.
Honey bee decline has brought about serious concerns for global food yield and has also drastically declined global economy. Millions of dollars worth of pollination service is being hampered by decline in honey bees. Carreck and Williams (1998) reviewed the economic value of honey bees and reported that “adding the value of honey and beeswax to that of pollination, the total value of honey bees [in the UK] can be estimated as £ 153.6 M. Using the estimate of 200000 colonies, the annual value to the UK economy of each honey bee colony is therefore about £800.” The value of honey bees, in agroecosystems, hence is undeniable.
Hence farmers need to be trained and made conscious of the potential threats of indiscriminate use of pesticides. Awareness, if spread across the farming community, can bring wonders for a greener earth devoid of toxic fumes and pesticides.
The reason for bee decline is not clearly defined. Pesticide exposure, mites and other parasitic infection, destruction of natural flowering habitats and uncontrolled destruction of nests especially in Eastern hemisphere for wild honey are the major drivers for global bee decline.
The Indian scenario is even more difficult because apart from constant habitat destruction, a multitude of pesticides are being used indiscriminately. Hence bees are not only constantly facing this immense pesticide load, they are also being thrown at the face of an array of deadly insecticides – all with the ability to severely hamper entire colonies of managed and wild honey bees.
These petite creatures are of massive value to us and our environment – they hold the key to plant life and yield. Their service – free and mostly unnoticed – ensures food for every home. A sustainable environment is what we all need to aim for collectively. Only when we can harness this steady decline in bee populations, we can look forward to a productive greener earth.