Imagine the world without natural fibers, fruits, vegetables or flowers. That's what our world would be like without insects and other animals that pollinate plants. Three-quarters of flowering plants rely on insects, birds or bats to move pollen from the male to the female parts of flowers for reproduction.
Most fruit, vegetable and seed crops, as well as crops that provide fiber, drugs and fuel, are pollinated by animals.
Pollination is critical to successful orchards, field and forage crops, home gardens, endangered species and ecological restoration.
As food producers and consumers, we need to be aware of the importance of pollinators to plants and the environment.
Most plants reproduce through seeds. But many can't do it by themselves. To make seeds, the female part of the plant, called a pistil, needs pollen from the male part of the flower, called a stamen.
Cross-pollination is the rule of thumb in the plant world. This means not only does pollen have to be transported from stamen to pistil but it also must come from separate flowers. Some plants rely on the wind to do this. Many others depend on animals.
Pollinators eat the flowers' nectar, and in the process get sticky pollen grains on their bodies. By moving from one flower to another, they transfer pollen to the pistils.
Bees, wasps, flies, butterflies, moths and beetles are important pollinators. Larger animals, such as birds (especially hummingbirds), bats, opossums and rodents also help to move pollen.
Plants often help their specific pollinators. This co-dependence is exhibited in many ways. Many night-pollinated flowers close during the day, to prevent thieves from getting at their nectar and pollen. Many daytime-pollinated flowers close at night for the same reason.
Flowers pollinated at night are usually white or pale yellow and very fragrant. This helps to announce the flowers' presence. Darker-colored flowers, not as visible at night, are usually pollinated by day-flying insects.
Flowers assist the pollinator in finding where the pollen or nectar is stored. Many have bee lines, dots or color variations that direct the pollinator. Flowers have many shapes: bowl, cup, star or tube. Shapes are specific to pollinators and, in some cases, also keep out unwanted pollen collectors.
Despite their importance to the economy and our lives, many pollinators are in trouble.
The honeybee, Apis mellifera, North America's most important managed pollinator raised specifically to pollinate crops, is in decline. Causes include parasitic mites, disease, pesticide poisoning, encroachment of Africanized honey bees and a phenomenon, Colony Collapse Disorder (CCD), where they leave the hive in search of nectar and do not return.
Many farmers depend on honey bees, leasing them during specific seasons to pollinate targeted crops. Declines in these managed pollinators can affect the availability, price and quality of fruits, vegetables and other products that depend on animal pollination.
The causes of decline in wild pollinators vary by species. Like the honeybee, the bumblebee has been hurt by the introduction of a non-native parasite carried by bumblebees imported from Europe for greenhouse pollination. Other pollinators have been affected by habitat loss or fragmentation, such as the destruction of cave roosts for some bats. A healthy ecosystem provides pollinators with habitat for foraging, nesting, roosting and mating. Homes, businesses and roads are replacing the native fields, wetlands and forests that are home to many pollinators. In addition, many of the wildflowers used by pollinators for food, nesting or egg-laying are rapidly disappearing.
Pesticides are also a threat. Many pesticides used on farms and backyard gardens are broad-spectrum types, meaning they can harm non-target species too. Many insecticides that get rid of plant pests are toxic to bees and other beneficial insects.
Pollinators such as bats, butterflies and hummingbirds face even more problems. They may migrate many miles over the course of a year, requiring nectar-producing flowers all along their journeys. But wildflowers and natural habitats are being replaced by development, which means that less food and habitat are available as they migrate.
There are many things that the public can do to help pollinators.
- Reduce the use of pesticides or, if possible, stop using them altogether. If one must use an insecticide, apply it in the evening, when many pollinators are inactive.
- Plant gardens filled with nectar-producing flowers for one's area. Go to http://pollinator.org/guides.htm and type in one's zip code to get information about pollinators in the area as well as a list of pollinator plants.
- If possible, leave tree stumps, dead branches and rotting trees on one's property. They provide nests or nesting sites for some bees and other insect species, as well as birds, bats and butterflies.
- If a bee's nest too is close to a home, don't destroy it. Contact a local beekeeper or the state cooperative extension service for advice about removing the nest without harming the bees.
Pollinator Week is June 22-28 this year. Go to www.pollinator.org for details on events, activities and resources.
To read or download a copy of the National Academy of Sciences report, Status of Pollinators in North America, go to http://dels.nas.edu/pollinators/.