1.
What is the pollination?
Flowers function as the
reproductive organ of the flowering plants.
The stamen which act as
the male part of the flowers is comprised of anther and filament. The function
of filament is bearing the anther. The anther produce large amount of pollen
grains which carry the male gametes of flowering plants.
The pistil which acts as female part in the
flowers consists of stigma, style, and ovary. Stigma in the pistil collects the
pollen grains. Then, pollen are transferred from stigma to ovaries through the
style. Ovaries produce the female gametes called ovules.
2.
What are the forms of pollination?
The pollination is
defined as the transferring the pollen grains from the anther to the stigma of
flowers. When the pollen grains are moved to stigma from anther of the same
flower or stigma of another flower in the same plant is called as “self-pollination”.
If the pollen grain from anther is moved to stigma of flower in another plant
is named as “cross pollination”.
3.
Who are the pollinators?
The flowers cannot
pollinate themselves without a help of external agent. Wind, water, and animals such as insects,
birds and bats act as the pollinating agents of the flowering plants.
Pollinators are the group
of animals that transfer the pollen grains from anther to stigma of flowers. Among
the animals, insects like honey bee, bumble bee, wasp, beetles, ants, flies and
butterflies, birds like Humming birds and mammals like bats involve in the
plant pollination.
Pollination is an
unintended act of these animals. They do pollination because of the reward they
receive from the flowers. The flowers offer food resources like nectar, oil and
mineral rich pollens and non- food sources like floral oil for the pollinators.
Apart from the other
pollinating agent such wind and water, pollinators alone are responsible for
the more than 80% of the pollination of flowering plants in the world.
4.
The role of Honey Bees as the
pollinators
Honey bees are identified
as one of social insect in the world. Their colony is comprised of queen,
female workers and drones. Only the queen has the ability to undergo
reproduction and produce the new generation of bees. The major function of
drones is the mating and fertilizing the eggs of queens. Workers females are
the most important members of the bees’ colony and only they are responsible
for the pollination of plants during their forage.
The honey bees are the
most important group of pollinators as they contribute to pollination of a
third of world’s crop plants. A typical honey bee visits more than 50 flower
within one collection trip. And also, within one trip they feed only one
species of flowering plants until the last crop of the cultivation and then
shift to another flowering species. Thereby, they assist for the cross
pollination among the flowering plants.
The flower offers nectar
and pollens as reward for the honey bees visiting them. Nectar is rich in
carbohydrates and later it is converted into honey by the bees. As a major part
of honey bees’ diet, the pollens offer essential nutrients like carbohydrates,
proteins, oil, and minerals for them.
Not all the honey bees
that visit the flower do not carry the pollens. Only small number of bees
transfer pollen and carry honey in a single trip. They transfer pollen from one
flower to another flower by attaching the pollen into specified hairy organs
called as “corbicula” in their hind legs. One honey bee can carry a
pollen load more than 50% of its body weight.
Farmers are directly
benefited by the action of pollination of bees. As a result of this volunteer
action of honey bees, the cost of the farming is reduced. Because, if the pollination
cannot be performed by the pollinators like bees, farmers have to spend money
on that.
Even though the crops
plant are pollinated by the bees, these types of crops are indirectly
advantaged by the bees as they help to increase the diversity among the crops.
Because, pollination of cover crops and other companion crops are able to
stimulate the growth of crops.
5.
Other functions of honey bees
1) As
biological indicator
The honey bees have been
used as a biological indicators of heavy metal analysis in the environmental
studies since 1972. Honey bees are used as a biological indicator in two ways.
Mortality rate of honey bees is observed after expose them to the toxic
chemicals containing pesticides or availability of less toxic substances
containing pesticides and heavy metals is analyzed in the residue in the
pollen, honey and their larvae.
2) Mitigation of global
Climate change
The pollination acts as
the foremost step of the plants reproduction. This action by honey bees help
the production of thousands of saplings of flowering plants around the world.
By increasing number of trees, bees help to regulate the climate change by enhancing
the carbon sequestration opportunities.
3) As a solution for
Human Elephant Conflict
Colonies of honey bees
can be established in the margin of villages near the forests instead of
electric fences. When elephant come towards the village and touch the honey bee
colonies, bees are disturbed and they start to attack the elephants. It causes
the elephants to go back to their native forests. Meanwhile, nectar from the
honey bee colonies provides an alternative income for the villagers.
4) Honey as an essential
ingredient
Honey extracted from the
honey bee colony has huge demand from the ancient times. Honey is used as the ingredient
in the preparation of foods and drinks. But due to the high amount of sugar
contain, intake of honey in large quantities should be avoided.
Honey is used as remedy
for the treatment in indigenous medicine because it has antibacterial
properties due to its high acidity. So, it has been believed that honey as
ability to cure the sore throats and cough.
Honey acts as good
preservative agent for foods under the right conditions. Its high concentration
of sugar prevent the growth of yeast and bacteria in the foods through the
osmosis. In ancient Sri Lanka, indigenous people used honey as preservative
agent for their meat.
Honey is used as
essential constituent in the manufacturing of cosmetics and personal care
products like facial and eye packs, bathing soaps, perfumes, and sun screen
products in the world.
6.
Threats for honey bees
1) Excessive use of
pesticides
As Farmers have shifted
towards profit oriented farming. So, they are tying maximize the crop yield by
increasing inputs. As a result, the
farmers tend to spray synthesized pesticides in large quantities. Even though these
innocent creatures are not targeted by application of these pesticides, but
this excess use of pesticides negatively effects the honey bees as they are
intolerance organisms to chemicals. As the constituents of the pesticides are
persistent in the environment, they tend to stay for long period of time and
cause death of more and more of honey bees. Thereby, it leads to local
extinction of honey bees. So, farmers have to find alternatives for the
pollination of their crops. They have to hire the bees from the bee keepers or
do the pollination by employing labors.
2) Deforestation and
habitat loss
Major threat for
existence of honey bees is the loss of habitats. Forest provides the habitats
for most of flowering plants as well as nesting sites for the honey bees.
Intensified agriculture, pasture lands, construction of roads, buildings, power
plants, and expanding human settlements acts as drivers of deforestation. Due
to the busy life style and lack of enough space, residents in the urban areas
are not interested in growing flowering plants for the attracting bees.
Moreover, deteriorated environmental conditions like air pollution do
not allow for bees to survive and flourish.
3) Pest attacks
Similar to other
organisms, bees are also subjected to infectious diseases originating from
certain bacteria, viruses, and fungi. But, the risk for the infections in bees
are increased, as their immunity get weaken by the exposure to synthesized
chemicals and unfavorable environmental conditions.
The
viruses transmitted through attack of varroa mite is recognized as a major
thereat for the existence of the honey bees all over the world.
4) Climate change
As a results of adverse
effects of climate change, frequency and intensity of natural disasters have
been increased and seasonality is also altered in the temperate countries.
Consequently, flowering season of some flowering plants has changed. And also,
most of flowering plants are died due to the extreme temperature results from
the prolonged droughts. Thereby, honey bees are unable find their forage on
time before the winter. The insufficient nutrition leads to the decline the bee
population globally.
5) Spread of invasive
plants
Although honey bees
cannot extract nectar and pollen grain from most of invasive plants because
invasive plants are lack of morphological modifications to enable the access of
the honey bee for the extraction. However, bees still can forage on some
invasive plants. Unfortunately, the substances including proteins and in the
pollen and nectar are detrimental to the bees. Furthermore, the invasion of the
invasive plant species causes the decline of the population of flowering plants.
It results in the loss of the forage of the honey bees.
7.
Attraction of honey bee to farm lands
and backyards
Wildflowers with bright colors like sun flowers should
be planted among the crops. Because, honey bees forage naturally on the
wildflowers than introduced ones. So, higher the number of wildflower plants,
higher number of bees can be attracted and beneficiated by the garden.
When selecting the crops species for the cultivation,
vegetables and fruit crops with fragrance and attractive flowers should be
planted. Pumpkins, cucumber, water melons, straw berries and black barriers are
the examples for the crops bearing bright color flowers.
In addition to offering flowers for the bees, shallow
tanks or ponds should be constructed for supplying water for drinking and
bathing and trees should be grown for proving shades for the coming bees.
Furthermore, the use of
synthesized chemicals containing pesticides, herbicides, and fungicides must be
minimized or avoided. Biological pest control methods should be
attempted. Flowering plants like Chrysanthemums were grown in the crops lands
to repel the harmful insects in Sri Lanka.
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