From "Envirozine: This Week in Canada's Environment"


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Protecting Plant Pollinators

Honeybee on flower. Photo: Maryann 
Frazier
Honeybee on flower. Photo: Maryann Frazier. Click to enlarge.

Threats to honeybees and its wild relatives have sparked Environment Canada and Agriculture and Agri-Food Canada researchers to discuss ways to protect this species and other insect pollinators. Since pollination is essential to crop and plant life, the Convention on Biological Diversity has adopted the International Pollinators Initiative to promote the conservation and sustainable use of pollinator diversity in agriculture and related ecosystems.


The International Pollinators Initiative identifies the need to monitor changes in the diversity and abundance of pollinators and to train specialists to keep inventories. Public awareness is a key focus as gardeners and farmers play a direct role in pollinator conservation.

Insect pollination is required for nearly all fruits and vegetables, including annual crops like tomatoes, peppers and strawberries, and tree fruits like apples and peaches. Crops like melons, pumpkins and cucumbers have separate male and female flowers, and would bear no fruit at all without insect pollinators. The value of pollination services for crops, like mustard, canola, alfalfa and fruits and vegetables has been conservatively estimated at $1.2 billion per year in Canada. Therefore, protecting honeybees and other important pollinators is essential to farmers' livelihood.

Threats to pollination

There are several factors contributing to the decrease in pollination. Habitat destruction, including nesting and mating sites, and alternative forage, is the main issue in the decline of wild pollinators. A diverse floral habitat provides the most abundant alternative forage. Flower-rich field borders, where non-crop forage plants are not treated as weeds, encourage a diversity of pollinators. On the other hand, clearing field borders, fence lines and hedge rows destroys habitat and eliminates alternative food sources. Prairie grasslands and natural pasture can support native pollinators if not over-grazed or brought into annual crop production. Also, cutting hay too early before bloom deprives native pollinators of their feed.

Another serious threat to pollination is pesticide use which has doubled in North America since 1960. Although many insecticides are more effective at killing beneficial insects than pests, a growing number of people spray pesticides on their lawns and gardens. Even at low levels, pesticides affect longevity, memory, navigation, and foraging abilities of the honeybee. The use of herbicides eliminates the natural forage that wild pollinators need before and after crops are in bloom.

Honeybee image with Varroa mite. Photo: 
Scott Camazine, Department of Entomology, Pennsylvania State University. 
http://maarec.cas.psu.edu/pest&disease/pppdIndex.html
Honeybee image with Varroa mite. Photo: Scott Camazine, Department of Entomology, Pennsylvania State University. Click to enlarge.

In addition, there are two predators attacking honeybees. The tracheal mite from South America attacks the bee's windpipe and eventually suffocates its victim. The varroa mite from Asia attaches itself externally and feeds on fluids from the host bee. These small relatives of the spider are responsible for the destruction of 30 to 50 per cent of beehives in Eastern Canada.

About the honeybee

There are 1000 wild species of bees in Canada. The domestic European honeybee remains the most important insect pollinator as it collects both pollen and nectar. A honeybee colony has one queen who produces up to 2000 eggs a day. She lives among hundreds of male bees called drones and more than 80 000 imperfect female bees. Despite its name, the honeybee is much more valuable as a pollinator than a honey producer. It has a long tongue, a hairy pollen-collecting coat and the ability to warm itself. A honeybee will visit many flowers over its lifetime. Despite being too small to trip the pollinating mechanism of some clovers and field beans, it is heavily relied upon because of fluctuating wild bee populations.

The role of farmers

Bee hives.
Bee hives. Click to enlarge.

Farmers can help conserve pollinators and protect their crops in several ways. To begin with, they must appreciate the important role honeybees play in pollination. For example, they should avoid spraying during crop bloom because this is when pollinators are most likely to visit. Farmers should consider planting different crops in smaller fields to promote pollinator abundance and diversity. Also, treating non-crop plants like thistles, milkweed, and chicory along fence rows and field borders as bee forage rather than weeds and setting aside herbicide-free meadows will provide alternate forage for bee populations.

Fast Facts

Pollination, the transfer of pollen from one flower to another, is critical to fruit and seed production in most plants.

Pollen is secondary to nectar as a floral feed reward for most insects. Because it is rich in protein and starch it is a vital food source for pollinators.

Butterfly pollinated flowers are actually the weakest scent, whereas flowers pollinated by nocturnal moths have a heavy sweet scent.

Orchard bees are more effective pollinators for apple blossoms. For lowbush blueberries, bumblebees, digger and mason bees are best. Cucumber, squash and pumpkins are pollinated by squash bees.

Flower-rich field borders, windbreaks and riparian forests encourage a diversity of pollinators.

There are more than 25 000 bee species in the world. The most important insect pollinators are solitary bees, bumblebees and honeybees.

Related Sites

Environment Canada Biodiversity Convention Office

Convention on Biological Diversity

North American Pollinator Protection Campaign

International Network of Expertise for Sustainable Pollination

Seeds of Diversity Canada

In the News

Honeybee hives stung by parasites (CBC May 02 2003)

La reine des abeilles (Radio-Canada - French only)

What home gardeners can do

Homeowners also play an important role in sustaining pollinator populations. Lawn areas offer little forage space for insect pollinators. Planting native flowers and allowing them to grow along borders can help increase the number of pollinators in the area. Most importantly, reducing or eliminating the use of pesticides around the home will help ensure a healthy pollinator population.

Citizens can ask local public officials and conservation authorities to set aside park borders, strips along fence rows and rights of way as protected areas for pollinator habitat. Hedges of natural and diverse vegetation can be planted in these areas to attract beneficial pollinators.

It's important to be aware of the delicate ecosystem of animals and plants that live in backyards, gardens, pastures and fields. Appreciate their roles beyond that of pests and weeds, and recognize that taking the proper measures will ensure healthy pollination.