This past week was National Pollinator Week, a time set aside to celebrate the amazing, monumental task that pollinators perform each growing season.
Worldwide, animals pollinate about 75 percent of all plant species and about 90 percent of flowering plants. And we all know that it takes a pollinated flower to produce many of the fruits we depend on in our diets, with animal pollination being responsible for about 1 of every 3 bites we take each day.
So, animal pollination is absolutely vital to life on this planet as we know it. However, life on earth was not always like we see it today. I have always been fascinated by the story of how the intricate diversity of interdependent life on our planet developed over the geologic time scale, which is billions of years long.
The story of how the plant-pollinator relationship evolved over the millennia is one we often take for granted in the flower-filled world we live in today. There was actually a time when flowers didn’t exist, and neither did pollinators as we know them.
Recent research has updated the insect tree of life to indicate that they evolved from ocean-
dwelling crustaceans around 480 million years ago. Around the same time, about 450 million years ago, plants first colonized land, also from the oceans.
However, neither early plants nor insects were like what we know today. For the first
300 million years, the plant kingdom was dominated by non-flowering plants, such as ferns, conifers and cycads.
I think the gingko, an interesting deciduous conifer, is one of the most commonly referred to ancient plants that we see today. However, the gingko and its early relation relied entirely on wind pollination to complete their life processes; insects were not part of the equation.
Early insects were actually flightless until about 400 million years ago. However, they get credit as the first life on earth to evolve the ability to fly. Over the ages, this special adaptation has served them well, granting them bragging rights for the most species-rich family tree on earth.
Somewhere around 150 million years ago, flowering plants (called angiosperms) abruptly emerged on the scene and there was an explosion of angiosperms over a relatively short period of time by evolutionary standards. Insects can be credited as fueling this explosion of species.
Early flowering plants did produce pollen, but the insect-attracting nectar we commonly associate with the plant-pollinator relationship today was not part of the equation yet. It was all about the pollen. The angiosperms produced abundant pollen, which is high in nutrition, and insects began to notice.
As insect species began using pollen for food, there was suddenly a perfect avenue for plant pollination to occur. The feeding insects would spread pollen from plant to plant, vastly improving the plant kingdom’s ability to disperse genetic information across the landscape.
Flowering plants that were pollinated by insects had a distinctive advantage over the archaic wind-pollinated species, and their numbers exploded. Competition between plants for attraction of pollinating insects lead to the development of many different sizes, shapes, colors and fragrances of flowers we see today. Eventually, this competition also lead to the addition of nectar as a sweet reward to insect visitors, which further diversified flower structures.
Nowadays, there are around 300,000 to 500,000 species of flowering plants, making up
9 out of 10 plants on earth. The efficiency of insect pollination has proven to be a mainstay of our natural world and vastly influenced the evolution and proliferation of flowering plants around the planet.
Today, insects still stand as the most species-rich group of animals worldwide. It is really shocking to me that a single species, Homo sapiens, has impacted global ecosystems so significantly that we are seeing sharp declines in pollinator populations. If this trend continues, we can expect worldwide crises as the plant world struggles to maintain vitality in both native plant populations and agricultural systems.
However, it’s not all doom and gloom, and there are things you can do to be part of the solution. Take some time during Pollinator Week to learn about and identify pollinators in neighborhood so you can better understand how to support them.
Consider reducing your home pesticide use since they are a major part of the problem. Or, best of all, plant some pollinator habitat on your property to provide resources for these invaluable members of our global ecosystem.
Ryan Pankau is a horticulture educator with the UI Extension, serving Champaign, Ford, Iroquois and Vermilion counties. This column also appears on his ‘Garden Scoop’ blog at go.illinois.edu/GardenScoopBlog.