Introduction
Worldwide are there more than one-quarter million flowering species of the plants on the earth which requires pollination. Over 75 percent of all plants rely on animal pollinators for the fertilization, of which about 200,000 species of animals at as pollinators. Around 90percent of insects especially bees contributes as the major pollinators providing pollination services to the crops directly and indirectly contributing for 15-30 percent of food production. Of the 124 major commodity crops directly used for human consumption, 87 (70 percent) are dependent on pollination for enhanced seed, fruits or vegetable production. These 87 crops are essential to our quality of life, providing the quality and diversity of the vegetables and fruits we eat and amount to 23×108 megatons (35 percent) of global food production volume is directly attributable to pollination. In 2006, pollinator dependent crops contributed 16.7 percent to total agricultural production in the developed and developing world whereas in 1961 it was 9.4 percent.
Pollination is the means by which pollen is transferred from the male part (anther) of the flowering plant to the female part (stigma), thereby enabling fertilisation, and the production of seed and fruit. In short, without insect pollinators our ecosystems would lose many of their flowering plants and simply cease to function, worse still there would be serious shortages of food. Pollination is the ecosystem services critical for the food production and human livelihoods and directly links with the conserving biological diversity in agricultural and natural ecosystems. Pollinators are animals that transfer pollen from one flower to another, mainly while drinking nectar and gathering pollen. The pollination services of these animals are critical for flowering plants to develop fruit with viable seeds that we (and wildlife) can eat.
Pollinators include bees, insects, birds and other animals that move pollen from one flower to another, thereby fertilizing plants and allowing them to reproduce. Pollinators are essential for the reproduction of many wild flowers and crops: for one out of every three bites eaten, one can thank over 25,000 species of bees which are responsible for a large portion of pollination services worldwide along with flies, butterflies, wasps, moths, beetles, and other invertebrates and, in some cases vertebrates such as bats, squirrels, birds and some primates are also known to pollinate natural plants and crops. Bees visit flowers for nectar (sugar for flying) and pollen (protein for their young). Pollinators can be considered an important link for agriculture, forestry, biodiversity, health, food security, food safety and nutrition.
Fertilization follows this pollination process by the sexual union of one of the two sperm nuclei of the pollen grain and the egg nucleus of the ovule to form the fertilized egg or zygote. Through this process of sexual union, a viable seed is formed that is capable of producing another complete plant. Some plants self-pollinate, that is, pollen transfer occurs within the same flower or among the flowers on a single plant, usually because the anthers touch the adjacent stigma. The majority of flowering plants, however, depend on the transfer of pollen from other individuals (cross-pollination).
Importance of pollination
Pollination is an ecosystem service which humans depend on through its link to world food production and it has become an often-cited example of how ecosystems services are economically valuable. Pollination is important not only in fruit or seed set, but also has enhancing role in getting higher yields, better quality, uniform ripening, plant vigor etc, and for flower tripping to produce viable seeds .
The importance of animal pollination varies substantially among crops, and therefore among regional crop economies. Many of the world’s most important cash crops benefit from animal pollination in terms of yield and/or quality and are leading export products in developing countries (e.g., coffee, cardamom and apple) and developed countries (e.g., almonds), providing employment and income for millions of people.
Pollinator-dependent food products are important contributors to healthy human diets and nutrition. Pollinator-dependent species encompass many fruit, vegetable, seed, nut and oil crops, which supply major proportions of micronutrients, vitamins and minerals in the human diet.
Pollinators are essential for orchard, horticultural and forage production, as well as the production of seed for many root and fiber crops. The benefits of pollination include not just abundance of fruits, nuts and seeds, but also their variety and quality; the contribution of animal-pollinated foodstuffs, it’s also provides to nutritional diversity, vitamin sufficiency and food quality to the human. The size and shape of fruits, the oil content and shelf life of the crops are all improved by insect pollination.
Globally, more than two billion people are affected by “hidden hunger,” a micronutrient deficiency caused by poor diet diversity. Pollinator losses leading to reduced diet micronutrients that plants that provides, may exacerbate the negative impact on health and economic development in certain regions. A large portion of the human diet and essential nutrients come from crops pollinated by insects, and the global area cultivated with these crops is disproportionally increasing compared with pollination-independent crops.
Importantly, the pollination increase the yield and improve the quality of many agricultural crops. Good pollination can increase the stability of crop production, reducing year to year and place to place variability in yield, by buffering effects of climate change and changing land use. If there are not enough appropriate insects available to pollinate crops that need it, then they will not yield to their full potential. As we think on the cultural and social aspects, pollinators, pollinator habitats and pollinator products are sources of inspiration for art, education, literature, music, religion, traditions and technology. Honey-hunting, practices based on the indigenous and traditional knowledge has been documented as recreation activities in more than 50 countries along with Nepal. Bees have inspired imagery and texts in religions all over the world, and bees like Apis dorsata, Apis laboriosa are the national identify for our countries. Honey bees, a major managed pollinator contribute to the income of beekeepers around the globe. Beekeeping can potentially be an effective tool for reducing poverty, empowering youth and creating opportunities to the conservation of biodiversity by adopting bee-friendly actions.
Economic importance of pollination
Globally the area of insect pollinated crops has increased and value added by pollination services is an increasingly important component of agricultural GDP in many nations, greatly increasing the need for secure, stable supplies of pollination services. On average, pollinator-dependent crops have higher prices than non-pollinator dependent crops. The distribution of these monetary benefits is not uniform along the universe.
Based on the pollinator dependency of the agricultural crops on animal pollinators to varying degrees, it is approximated that three-quarters of all crop types grown by humans require pollination by insects, a service estimated to be worth between $235 billion and $577 billion per year worldwide accounted to 5-8 percent of the current global crop production. The volume of agricultural production dependent on pollinators has increased by 300 percent in the last 50 years since their contribution is on the rise. In the absence of animal pollination, changes in global crop supplies could increase prices to consumers and reduce profits to producers, resulting in a potential annual net loss of economic welfare of $160 billion‒$191 billion globally to crop consumers and producers and a further $207 billion‒$497 billion to producers and consumers in other, non-crop markets
Pollinators are a source of multiple benefits to people well beyond food-provisioning alone, contributing directly to medicines, biofuels, fibres, construction materials and provide a wide range of resources such as food and shelter for many other invertebrates, mammals, birds and other taxa which economically contributed more than 3 trillion dollars annually.
Pollinators decline scenario
In the scenario of increasing the cultivation of the pollinator dependent crops worldwide, the decline in the pollinators diversity has been noticed in the regional level which reduce the yield growth and stability of pollinator-dependent crops. The abundance and diversity of the wild bees have been found decline strongly in the agricultural systems far from the natural and semi-natural habitat. It is estimated that 80 percent of the pollination of global crops can be attributed to the activities of just 2 percent of wild bee species. A diversity of pollination options, including both wild and managed species, is needed in most open field systems.
In 2018 the World Wildlife Fund and Zoological Society of London’s Living Planet estimated that more than half of vertebrate wildlife (fish, amphibians, reptiles, mammals and birds) i.e by 60percent between 1970 and 2014 has been lost. The invertebrates groups are in majority as compared to the vertebrates which is dominated by the insects groups. A report form 2019 estimated that, on average, insects are declining by 2.5 percent each year, with 41 percent of insect species threatened with extinction. Likewise, the International Union for Conservation of Nature (IUCN) Red List assessments indicate that 16.5 percent of vertebrate pollinators are threatened with global extinction (increasing to 30 percent for island species).
Strong declines of some pollinator taxa over the last few decades have been observed in the regional and national assessments of insect pollinators indicate high levels of threat, particularly for bees and butterflies (often more than 40 percent of species threatened). In Europe, 9 percent of bee and butterfly species are threatened and populations are declining for 37 percent of bees and 31 percent of butterflies (excluding data deficient species, which includes 57 percent of bees). At the national level, where Red Lists are available they show that the numbers of threatened species tend to be much higher than at the regional level. The World Economic Forum’s suggests that the global decline in biodiversity overall could have repercussions on everything from health and socioeconomic development to productivity and even regional security.
Factors causing the pollinators declines
The pollinators are declining in abundance in many parts of the world due to the changes in land use and landscape structure, intensive agricultural practices, monocultures and excessive use of the agricultural chemical have led to large-scale losses, fragmentation and degradation of their habitats and the climate change. The pests and diseases resulting on the managed honeybees pose a special threat for the honeybee colony loss. Furthermore, climate change like higher temperatures, droughts, floods, other extreme climate events and changes of flowering time hinder pollination largely by desynchronizing the demand (flowers in bloom) with the supply of service providers (abundant and diverse populations of pollinators). The worrying decline in the number of pollinators is related to pest and disease outbreaks, and higher levels of malnutrition and non-communicable diseases, provoking health issues for populations around the world.
Especially, the intensive agricultural practices high use of agrochemicals and intensively performed tillage, grazing or mowing are known to lower densities and diversity of foraging insects and alter the composition and structure of pollinator communities from local to regional scales. The pesticides used can poison or impair their reproduction of the pollinators. These chemicals can be chronic to the plant losses which eliminate nectar sources for pollinators, destroy larval host plants for moths and butterflies, and deplete nesting materials for pollinator species. Similarly, the loss of habitat through land use changes, e.g. due to conversion of natural areas to agriculture, mining or urban development, has been identified as the principal cause of pollinator decline. The loss of the habitat causes the reduction of food sources, fewer sites for mating, nesting and migration for the pollinators.
Climate change is also considered a significant potential threat in Europe and North America. Bumble bees are failing to track warming by colonizing new habitats north of their historic range. Simultaneously, they are disappearing from the southern portions of their range. Some species have declined severely.
Conservation and management of pollinators
The pollinator friendly practices can be adopted for the conservation and management of the pollinators. For the conservation of the pollinators a landscape-wide approach for the creation of the habitats should be better understood. The awareness and management and development of the pollination-friendly farming practices could be the effective initiation for the conservation of the pollinators within the agroecosystems. Pollinator-friendly measures have the potential to increase productivity and sustainability and contribute to the long-term viability and profitability of food production systems. The general pollinator management practices include are as follows:
- Conserving and restoring natural habitat.
- Growing flowering plants preferred by pollinators.
- Promoting mixed farming systems.
- Establishing nectar corridors for migratory pollinators.
- Providing habitats alongside cropland for pollinator nests and food.
- encouraging integrated pollination and pest management (IPPM)
- Discouraging misuse of agrochemicals.
- Minimum tillage and create the nesting habitat for the bees
The more havoc practices is the pesticide exposure that can be reduced by decreasing the usage of pesticides, for example by adopting Integrated Pollination and Pest Management (IPPM) practices and where they are used, the impacts of pesticides can be lessened through application practices and technologies to reduce pesticide drift. The awareness activities and the training are necessary to ensure that farmers, farm advisers, pesticide appliers and the public use pesticides safely.
Conclusion
The world population will be increase by the 1.5 times by the 2050. To feed the growing population the agriculture production should be boost by the double. In this situation, to meet the challenge of increasing the agricultural production, the pollination services provided by the insects should be ensure to increase to the higher yields of the crops. The loss of insect pollinators have evidenced in the national and regional level which will has large potential consequences on human food production and nutrition directly through reduced crop yields. To mitigate the loss, the pollinator friendly practices should be adopted with the close coordination of the policymakers, farmers and other stakeholders for the conservation and management of the pollinators for the sustainable agriculture crop production.
Writer Kedar Devkota is currently an Assistant Professor at Agriculture and Forestry University in Rampur, Chitwan.
