Pollination plays a vital role as a regulating ecosystem service in nature. Among the insect pollinators, solitary and social bees provide most pollination in both managed and natural ecosystems. Most of the world’s staple foods, including wheat, corn, and rice reproduce without insect pollination. These crops account for 65% of global food production, still leaving as much as 35% depending on pollinating animals (Klein et al. 2007). In part due to the massive scale and homogeneity of modern agriculture, the majority of crops requiring pollination are dependent on managed pollinators, and especially on managed honeybees (Aizenet al. 2008).
Pollination is an ecosystem service that is key to food security. Pollinators are essential for many fruit and vegetable crops. In agriculture, especially among pollen-limited crops, promoting pollination services is a means of increasing productivity without resorting to expensive agricultural inputs of pesticides or herbicides.
Indeed, pollination services are most likely underpinning productivity in many crops without farmers even recognising it, so long as habitat and alternative pollinator forage are readily available as they often are in small holder farming systems. Increasing dependence on pesticides for pest control is also highly detrimental to beneficial insects such as pollinators, unless planned and undertaken with extreme care.
Pollinator-plant interactions have been estimated to encompass almost 400,000 species, the precise nature of the relationship between plant and pollinator varies enormously. Although some animals visit flowers for nectar or pollen, not all flower visitors bring about pollination. Effective pollinators often have behavioral and anatomical traits that greatly increase the efficiency and accuracy of pollen delivery (Proctor et al. 1996; Lewinsohn et al. 2006). In general, pollination is a mutually beneficial interaction; pollinating animals receive some form of nutritional “reward” for visitation and pollen delivery. Pollen itself can be a reward, serving as the primary food resource for most larval bees and as an important source of protein for some flies, butterflies, birds, and bats. Other plants provide nectar, oils, resins, fragrances, pheromone precursors, and other resources to induce visitation and pollen delivery (Roulston and Cane 2000).
No other group of insects is of more benefit to humans than bees. More than one-third of the world’s crops require pollination to set seeds and fruits, and most meat and dairy industries rely on bees for pollination of fodder (clover and Lucerne) (Diaset al. 1999).
Crops relying on bee pollination include apple, citrus, tomato, melon, strawberry, apricot, peach, mango, grape, carrot, potato, onion, pumpkin, bean, cucumber, sunflower, various nuts, alfalfa, etc. The annual value of this service is estimated at US$112 billion worldwide (Southwick and Southwick 1992).
Even crops that do not require pollination for harvesting, such as those producing fibre or timber, still require pollination to produce further generations, and crops such as cotton that do not require pollination to produce seeds, provide greater yields when pollinators are available (Allen-Wardellet al. 1998).
Apart from direct benefits derived from honeybees in the form of honey and beeswax, indirect benefits realized by way of increased yields of certain farm crops and forest products due to their pollination services are immense.
Domesticated species: There are two most important hive species. European honeybee, Apis mellifera L. is a native of old world except tropical Asia and introduced to most parts of the new world. It has a foraging range of 3 km. The Indian hive bee, A. cerana indica F., a native of tropical Asia is prevalent in a wide region with a flight range of 1.5 km. It is even a better pollinator than A. mellifera because of their longer foraging period and many other characters (Sihag and Mishra 1995).
Wild species: Two other species, A. dorsata (rock/giant bee) and A. florea (littlebee) are also native of tropical Asia and efficient pollinators. But these cannot be managed for long time, as they do not live in artificial hives. Their foraging range is 2.5–4.0 and 1 km, respectively.
Honeybee species can effectively be utilized for pollination of crops because
The population of both wild and managed pollinators is declining at alarming rates owing to alteration in their food and nesting habitats, shrinkage in natural ecosystems, i.e. forests and grassland ecosystems, pesticide poisoning, diseases and pests, over-collecting, smuggling and trading in certain rare and endangered species. The focus of beekeeping needs to change from conventional honey production to crop pollination.
A crop’s pollinator dependence differs between species, including between crops and crop varieties. Some plants must be cross-pollinated, others do not need pollinators but produce better fruit and seed if pollinated, and a number of them are strictly self-pollinated. Further, plants differ in their pollinator-type requirements; some require specific pollinators while others are pollinated by a variety of visitors, and many are wind pollinated. Effective pollinators of the same crop may vary from one site to another. Specific knowledge on pollinator dependence and types is important for agriculture and biodiversity (including agro-biodiversity) conservation.
One mistake often made by a fruit, vegetable, or seed producer regarding bee pollination is to assume that “the neighbor’s bees” will provide sufficient pollination of his crop. Although honeybees from a single hive will fly 2–3 miles from the colony, the radius of greatest efficiency and greatest pollination is only 200–300 yards from the colony. There are many flowers competing for the bee’s attention; some may be more attractive or “profitable” to work than the crop needing pollination. Bees will not fly a great distance to forage on an unattractive crop.
By moving bees directly into a field, a grower can increase the flight activity in that area. However, there are several considerations one should make, and procedure one should follow.
The fact that the bee pollination enhances crop yields has been established (Abrol 1993). Evidently, bee/insect should be encouraged for increased and sustainable agriculture production. In India, the total cultivated area is about 160 million hectares and at least one third (if not half) of the areas is under entomophilous crops which require insect pollination.
At a very modest rate of 3 colonies per hectare we need 160 million colonies of honeybees but against this requirement we have just less than one million bees colonies at present. This would be possible only if the apiculture as a whole gets boost and number of colonies are multiplied and managed. Besides, it is very necessary to survey different agroclimatic zones to determine the distribution and abundance of pollinating insects so that pollinators specific to different zones are multiplied and managed. Regions with less abundance should be supplemented with apiaries.
Pollination is a service Nature provides that we have tended to take for granted, and that we often do little to encourage until we start to lose it. As wild ecosystems are increasingly converted to more human dominated uses to meet the compelling demands of food security, it is critical for us to understand what pollination services are most important for food security, and how we can preserve pollinator services in sustainable farming systems.
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