Introduction
Our demand for food is increasing with the increasing human population. To cope with this situation, our agriculture system needs more food production through a sustainable management system. Pollinators play the most vital role in food production.
Ways of Pollination
Out of 115 leading global crops of human consumption, 87 depend on animal pollination to some extent. Five to eight per cent of global crop production with a market value of about 235 to 577 billion US dollars can be directly attributed to animal pollination. About 200,000 different animal species are found to act as pollinators, insects, by far the largest group and bees play the most important role in pollination.
- A plant species can be visited by different pollinators in different regions; they can be generalist pollinators or highly specialized for a particular plant, depending on changing abundance of pollinator species.
- Insects are one of the important pollinators of mango plants, honeybees in Brazil, bumble bees in Israel, and flies in Malaysia, India, Colombia, Costa Rica, and the Philippines.
- Pollinators help farmers in different ways by increasing the quality and volume of crop production. An example is CropLife India, which aims to raise awareness of the importance of honeybees to the yield of crops, by providing bee hives, training farmers for managed crop pollination and integrated pest management.
- Pollinator diversity also improves the yield of commercially important crops, like strawberries pollinated by flies, solitary bees, and honey bees are larger in size and brightly coloured.
- Both plants and their pollinators depend on environmental factors. Ambient temperature affects flower phenology and behaviour of the insect pollinator.
- Altitude can also play an important role in the activity of pollinators and competition among diverse insect groups and nontarget plants flowering abundantly also affect the yield of crops.
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List of Major Insect Pollinators
| Insect order | Family | Common name |
|---|---|---|
| Hymenoptera | ApidaeHalictidaeSphecidaeMegachilidaeIchneumonidaePompilidae | Honey beeSweet beeThread-wasted waspLeafcutter beeIchneumon waspSpider hawk wasp |
| Coleoptera | CarabidaeChrysomelidaeElateridaeMordellidaeTenebrionidae | Ground beetleLeaf beetleClick beetleTumbling flower beetleDarkling beetle |
| Lepidoptera | LycaenidaeHesperiidaePieridaeNymphalidaeNoctuidaeSphingidae | CoppersSkippersWhite and sulfur butterflyBrush-footed butterflyMothHawk moth |
| Diptera | SyrphidaeAsilidaeBombylidaeCalliphoridae | Hover flyRobber flyBee flyBlow fly |
Major Threats to Pollinators
- Many pollinators are lost due to habitat degradation and urbanization. Many bees and butterflies are habitat-specific, and loss in habitats causes them to go for overwintering, foraging for pollen and nectar, or nesting, which can be detrimental to their survivability. The decline in habitat quality and its fragmentation can be another concern like loose soil required for ground nesting of bees can be crushed by heavy foot traffic or road vehicles.
- When non-native plants take over an agriculture field, they crowd wildflowers specific for certain butterflies and bees for nectar, pollen, and larval food. Some non-native plants can compete with native plants and attract pollinators towards them, causing failure of pollination of target plants. In some cases, some non- native bees can also compete with native bees for nectar and pollen. Some non- native insects used for biocontrol like the nine-spotted lady beetle feeds on the caterpillars of the Monarch butterfly and have eliminated a major population of these important pollinators.
- Pollution can be a major threat to bees and other pollinators which rely on floral scents for food.
- Light pollution can harm moths by increasing their vulnerability to bats and birds. The use of pesticides by aerial spraying is a cause of threat to insect pollinators, carrying persistent chemicals which thrive for a long in the environment. Insecticides contaminate pollen grains and herbicides eradicate important plants for foraging bees and other pollinators.
- Climate change will alter the relationship of pollinators with their host plant. Flowering plants which are shifting their range to cooler, northern regions in response to lower habitats with warmer temperatures may not be in synchrony with their pollinators. The composition of their pollinators is expected to change.
- The decline in pollinator populations is occurring due to colony collapse disorder (CCD), a combination of several factors like mite attacks, diseases, mismanagement of bee hives, invasive species, GMO crops, and chemical contamination through pesticide use.
Conservation of Pollinators
Plants which are visited by insect pollinators are during flowering, at a particular time of the year. At other times of the year, it is necessary for us to identify these plants, foraged by pollinators by maintaining a floral calendar for a given region. If the target crops are growing near forests, the plant species growing in their vicinity should also be identified. Common weeds growing in that area should also be marked. All this information can help to analyse and develop conservation strategies for the plants and their pollinators.
Conclusion: Economic Importance of Pollination
Pollination is Nature’s free ecosystem service. If pollinators were absent, we would not be having such a variety of fruits, vegetables, oilseeds, and pulses, which forms an important part of our daily diet in maintaining our health. Therefore, it is important for us to determine the service value of pollination and obtain knowledge on the pollination methods of different common crops for better yield and sustainable agricultural management.