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



Published in: Volume 07 Issue 30

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