Pollinators decline; a threat to world food supply

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Pollination is a natural ecological process that benefits mankind and is mainly done by insect


population. Insects pollinate crops, assist the process of food production and significantly


increase the yield of certain crops. Pollination is the transfer of pollen from the male parts of a


flower to the female parts of a flower of the same species, which results in fertilization of plant


ovaries and the production of seeds. Pollinators visit flowers in their search of food. During a


flower visit, a pollinator may accidentally brush against the flowers reproductive parts,


unknowingly depositing pollen from a different flower.


The plant then uses the pollen to produce a fruit or seed. Many plants cannot reproduce without pollen carried to them by foraging


pollinators. Absolute figures on the overall economic value of pollination vary considerably from


source to source; however, pollination improves yields and therefore the availability of food.


According to the TEEB report (2010), the total economic value of insect pollination globally is


estimated to be €153 Billion, which equates to 9.5% of agricultural production. The estimated


value of insect pollination for European agriculture is €22 Billion.


Pollinated crops include those that provide fruit, vegetables, seeds, nuts and oils. Many of these


are important dietary sources of vitamins and minerals, without which the risks of malnutrition


might be expected to increase. Several crops also represent an important source of income in


developing countries from the production of coffee and cocoa. Chocolate is derived from cacao


tree seed (annual world cocoa bean crop value, US$5.7 billion). Cecidomyiid and ceratopogonid


midges are essential for its pollination. In addition to food crops, pollinators contribute to crops


that provide biofuels, fibers, medicines, forage for livestock and construction materials. Crops


usually show a high diversity in pollination requirements. Cereal crops such as wheat, rice and


corn are either wind or self-pollinated and do not require insect pollination.


However, some crops rely on biotic pollination. Pome and stone fruits rely heavily on insect


pollination, in fact insect pollination can increase yields in cherry and plum crops by 80 and 30%


respectively. Globally, 264 crop species have been identified as being dependent or partially


dependent on insect pollination. In fact, 57 crop species exhibit an increase in yield due to biotic


pollination. Moreover between 15% and 30% of food consumed by humans in developed


countries requires an animal pollinator. Three-fourths of the worlds flowering plants and about


35% of the worlds food crops depend on animal pollinators to reproduce. Pollinating insects


also play a critical role in maintaining natural plant communities and ensuring production of


seeds in most flowering plants. There are more than 20,000 species of wild bees alone plus many


species of butterflies, flies, moths, wasps, beetles, birds, bats and other animals that contribute to


pollination. More than 3,500 species of native bees help increase crop yields. Some scientists


estimate that one out of every three bites of food we eat exists because of insect pollinators.


The volume of agricultural production dependent on animal pollination has increased by 300 per


cent during the past 50 years, but pollinator-dependent crops show lower growth and stability in


yield than crops that do not depend on pollinators. This is because a growing number of


pollinator species worldwide are being driven towards extinction by diverse pressure many of


them are human made, threatening millions of livelihoods and billions of dollar worth of food


supplies. Pollinators are also threatened by the decline of practices based on indigenous and local


knowledge. These practices include traditional farming systems; maintenance of diverse


landscapes and gardens; kinship relationships that protect specific pollinators and cultures that


are connected to pollinators.


The main threats facing pollinators are habitat loss, degradation and fragmentation. As native


vegetation is replaced by roadways, manicured lawns, crops and non-native gardens, pollinators


lose the food and nesting sites that are necessary for their survival. Migratory pollinators face


special challenges. If the distance between the suitable habitat patches along their migration


route is too great, smaller, weaker individuals may die during their journey.


The improper use of pesticides can negatively impact pollinators and their habitats. Pesticides


include products, such as weed killers and insecticides, which are designed to prevent, destroy,


repel or reduce pests such as insects, mice and other animals, weeds, fungi, bacteria and viruses.


Pesticides are used in nearly every home, business, farm, school, hospital and parks and are


found almost everywhere in our environment. By their very nature, most pesticides pose some


risk of harm to humans, animals, beneficial insects and the environment because they are


designed to kill or adversely affect living organisms. However, at the same time, pesticides are


useful to society because they are used to control or kill potential disease-causing organisms and


insects, weeds and other pests.


Therefore, it is important to use these products only when necessary (rather than on a regular


schedule), use the minimum amount required to be effective, and to target application so that


only the intended pest is affected. Genetically modified crops are usually either tolerant to


herbicides or resistant to pest insects. The former reduces the availability of weeds, which supply


food for pollinators. The latter often results in lower use of insecticides and may reduce pressure


on beneficial insects including pollinators. However, the sub-lethal and indirect effects of GM


crops on pollinators are poorly understood and not usually accounted for in risk assessments.


Given that habitat loss and agricultural intensification are known to decrease pollinator richness


and abundance, there is a need to assess the consequences for different components of crop


production.


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Published in: Volume 07 Issue 30

Short Link: http://www.technologytimes.pk/?p=15999