Honeybees are eusocial insects whose colonies normally consist of a queen, a handful of drones and ten to twenty thousands worker bees during the honey flow season. They produce honey, the first biological sweet, commonly known as nature's golden wonder, in addition to a few commercial bee/hive products like beeswax, propolis, royal jelly, bee pollen, bee venom, etc. Honeybees play a crucial role in the maintenance of biodiversity by enhancing the production of agricultural and horticultural crops in a significant rate through cross-pollination.
Environmental pollution is one of the most hazardous problems of mankind across the globe. Growing human population coupled with rapid industrialisation and uncontrolled application of numerous kinds of pesticides, primarily in rural areas, has created havoc by releasing inorganic and organic contaminants into the environment. The level of environmental pollution can be determined by physical, chemical and bioindication methods. Recently, more attention has been given to living organisms as indicators of environmental health.
A bioindicator is an anthropogenically-induced response in biochemical or physiological parameters that have been linked to biological effects of an organism, population or community. Honeybees are active biological indicators, as they are known to exhibit the chemical impairment of environment. Several ecological, ethological and morphological characteristics have made the honeybee a reliable ecological detector. They sample most of the environmental sectors like vegetation, water, soil and air. They supply a suitable amount of biological material to be easily sampled and analysed throughout the year. A forager bee flies about the surrounding area of about 4 to 5 km from the hive, especially picking up airborne particles with its body hair, while collecting pollen and nectar from flowers. It is because of this large-scale surface area that honeybees and their products have been proposed as suitable bioindicators of environmental pollution.
In other words, the forager brings samples into the hive by gathering nectar and pollen from flowers, propolis from some plant species, honeydew from aphid infested plants and water from various sources along with possible contaminants to be present in the air. They are like flying dust mops with electrostatic charges on their bodies, picking up both pollen and dust particles. On return to the hive, the nest-mates in the hive fan the air furiously with their wings by releasing the pollutants in the hive. Occasionally, bees also accumulate residues in their bodies, by stockpiling contaminants on direct exposure to residual pesticides. They are active throughout the day and each forager successfully completes 12 to 15 foraging trips a day, visiting for collection of pollen and nectar from various flowers. It was observed that a quarter or 5,000 of the 20,000 bees in a normal colony are active pollinators.
Thus, analysis of the air and the bees in the hive could identify the nature of pollutants in the locality.
Honeybees are extremely sensitive to various odours and have the ability to detect and discriminate different odoriferous substances as biosensors. They are able to learn and remember the olfactory stimuli in discriminating varieties of odours. In addition, bees can be trained to detect not only natural odours but also those of explosives, chemical and biological warfare agents. Similarly, these are highly sensitive to most plant protection products, revealing their improper spread in the environment through pesticide poisoning of both immature and adult stages. More recently, the services of bees have been extended in the routine monitoring of volatile and semi-volatile organic contaminants in the environment.
Hitech portable electronic hives are installed at the test sites for the detection of contaminants. A small copper tube attached to the side of each hive pumps air out without disturbing the bees, which could be used for analysis. It passes through filters that trap organic components. On heating, volatile components pass through a gas chromatography, followed by a mass spectrometer. This excels the identification of contaminants in the air in the given locality.
Millions of bee colonies of five species of honeybees, both wild and domesticated, are available in both rural and urban regions of the country. A huge number of wild bee species such as rock bee, Apis dorsata, dwarf bee and Apis florea could also be seen in the central parts of many metropolitan cities of India, including Bangalore, for the rich availability of pollen and nectar sources. Instead of having people go out to gather samples for the laboratory for analysis, bee scientists hope to recruit a force of thousands of bees to do the job.
Bee monitoring also contributes to the determination of ecological impact of pesticides by culminating in the charting of environmental health maps. This indicates that busy bees will be working not only for their colonies but also for human welfare by producing commercial hive products including honey and as bioindicators of environmental pollution by forecasting their impact on human health.
