Pollination!

Nature provides ecosystem ser­vices that make life possible here on earth. There are four types of ecosystem services; provision­ing, supporting, cultural and reg­ulating services. In this newsletter issue, we will highlight pollination, one of the regulating ecosystem services essential for food security, food diversity and human nutrition.

What is pollination?

The important priority of every living organism is to creating off­spring for the next generation. Plants need to produce fruits and seeds to make offspring, a new plant. Seeds /fruitscan only be produced when pollen grains are transferred from the anther, which is the male part of the flower, to the stigma, a female part of the same species. This process is called pollination.

How does pollination occur?

We know that plants are not able to move from one place to another, so how does pollen get transferred from anther to the stigma? Flowers rely on agents to move pollen from the anther to the stigma of the same or different plant but of the same species. These agents can include wind, water, birds, insects, butter­flies, bats, and other animals that visit flowers. Living animals that can transfer pollen are called pollinators. The pollinator is often eating or col­lecting pollen for its protein and oth­er nutritional characteristics or it is sipping nectar from the flower when pollen grains attach themselves to the animal’s body. Pollination can there­fore be called a symbiotic relation­ship between a plant and pollinator.

Types of pollination

Two types of pollination exist which are cross-pollination and self-pol­lination. Cross-pollination occurs when pollen grains are transferred from the anther to the stigma of a different plant whereas, in a self-polli­nation, the transfer of pollen grains is from an anther to a stigma of the same flower or plant. Each of the pollination types has advan­tages and disadvantages, which we are not going to look at in this issue. What is important to note is that self-pollination occurs in species with closed flowers, there­fore, limiting access to pollination agents to flower’s sexual structures.

Pollination syndromes

Each plant posses specific floral characteristics that favour a specif­ic or a group of pollination agents. This includes; flower type, shape, color, odor, nectar, and structure. These floral characteristics and their relationships with the favoured pol­linators are called pollination syn­dromes. Pollination syndromes are a symbiotic relationship between the plants and the agents or animals in which both benefit. Animals forage on the flowers for carbohydrates (in nectar) and proteins (in pol­len grains), which are the rewards.  On the other hand, the plant provides animals with nec­tar and pollen to guarantees its pollination and reproduction.

The following pollination syndromes are recognized: cantharophily (bee­tles), melittophily (bees), myoph­ily (by flies), psychophily (butter­flies and moths), chiropterophily (bats), and ornithophily (birds). In these pollination syndromes, the pollen grains are attached to some parts of the animals and become brushed onto the stigma. 

Pollination and food security

Pollination is an important ecosys­tem service for food production therefore, global food security. How­ever, animal pollinators are current­ly threatened by habitat destruction and unsustainable agricultural prac­tices such as intensification and pes­ticide misuse, risking global food security. The current increase in the human population (projected to be 9 – 10 billion by 2050) will put more pressure on the food production sys­tem. This will have a negative effect on future food security, especially in developing countries like Tanzania.

A balance between plants and pol­lination agents in ecosystems was maintained for centuries and has been key to sustainable food pro­duction and a healthy ecosystem. But the current surge in monocul­ture farmland, expanding agricul­tural land wildfires and diseases, the balance is constantly disturbed. The Sustainable Development Goal 2, Zero Hunger is highly dependent on effective pollination and polli­nators’ conservation. According to the United Nations, about 2 billion people in the world did not have regular access to safe, nutritious and sufficient food in 2019. With the ongoing destruction of ecosystems and unsustainable agricultural practices, there is little hope that the world will achieve the Zero Hunger target by 2030. Under the business as usual scenario, the number of people affected by hunger would surpass 840 million by 2030.