Pollinators are animals, mostly insects, and primarily bees, but also birds and bats and a few other animals that help plants produce fruit and seed. Pollinators transfer pollen between the male and female parts of flowers more or less accidentally while they are collecting food in the form of pollen and nectar. We say “more or less accidentally” because it turns out that in the long run, doing so is beneficial to both the pollinators and the plants.
Almost three-quarters of all the flowering plants in the world rely, at least to some degree, on pollinators to play this role (CSPNA 2007). In fact, we can call it a “service” because from both the plant’s perspective and ours, that is what it is. And because of this, entire terrestrial ecosystems, within which these flowering plants grow and interact, depend on this service – from Amazon forests (most tropical tree species are insect pollinated (Michener 2007)) to the native grasslands in the North American Great Plains, to the vegetated “green” zones along prairie streams in western Canada. And if that wasn’t enough, pollinators are vital to agriculture (Table 1). Most fruit, vegetable and seed crops (about 70 percent) are pollinated by animals (Klein 2007) as are some fibre crops (e.g., flax and cotton) and major forage-seed crops like alfalfa and clover (Michener 2007). Some crops are entirely dependent on insect pollination for seed and fruit production while others benefit from higher yields, better quality produce, or more uniform maturation (Corbet 1991; Delaplane 2000). In fact, roughly 35 percent of global crop production depends on pollinators (Klein 2007), and even more, these plants tend to be nutritionally very important to our diet – they provide about 90 percent of our vitamin C, all of our lycopene, almost all of the antioxidants b-cryptoxanthin and b-tocopherol, most of the lipid, vitamin A and related carotenoids, calcium and fluoride, and a large amount of the folic acid intake (Eilers 2011). In the case of honey bees, which provide the majority of agricultural pollination done by bees, they also produce useful and economically important products: wax and honey.
Table 1: Major crops grown in Canada that depend on or benefit from insect pollination.
- Legumes and relatives - Bean, Lima Bean, Soybean
- Vegetables - Cucumber, Peppers, Pumpkin, Squash, Tomato
- Vegetables (seed) - Asparagus, Beet, Broccoli, Brussels Sprouts, Carrot, Cauliflower, Celery, Lettuce, Onion, Parsnip, Radish, Rutabaga, Turnip
- Fruits, berries and nuts - Apple, Apricot, Blueberry, Cherry, Cranberry, Melons, Peach, Pear, Plum/ Prune, Raspberry, Strawberry, Watermelon
- Oils, seeds and grains - Alfalfa, Buckwheat, Canola, Flaxseed, Mustard Seed, Sunflower
- Clover and relatives (seed) - Alsike Clover, Red Clover, White Clover, Yellow Sweet Clover, White Sweet Clover
The number of honey bee colonies in Canada has been increasing over the last five years from about 570,000 in 2008 to more than 706,000 in 2012 (Agriculture and Agri-Food Canada 2013) as beekeepers import more and more bees to fulfill increasing demands for pollination services as requested by farmers. For wild bees, there are indications that their abundance and diversity is declining and that some species are already at risk (COSEWIC 2010; CSPNA 2007). For the domesticated and agriculturally-important European honey bee, annual losses in the range of 15-30 percent of colonies in North America, primarily due to over-winter kill, appear to be typical (van der Zee 2012; vanEngelsdorp 2012). However, since 2006, a phenomenon termed Colony Collapse Disorder has been reported in the United States where entire colonies are lost because of what appears to be a combination of factors that are difficult to gauge, thereby adding to the vulnerability of pollination services to agriculture (Dainat 2012).
While the causes of all of these declines (wild and managed bees) can be hard to pin down, the following are among the culprits:
- declines in the diversity of flowering plants (Di Pasquale 2013);
- loss, fragmentation and degradation of habitat due largely to agriculture and urban development (Grixtia 2009; Kremen 2002; Larsen 2005; Richards 2001);
- the introduction of invasive non-native plant species (Potts 2010);
- the toxicity and widespread use of pesticides (Desneux 2007; Kevan 1975; Pettis 2013);
- air pollution (Girling 2013);
- climate change (Potts 2010); and
- diseases and parasites (Potts 2010).
Fortunately, beekeepers have been able to increase the number of honey bees that they import from other countries, not only to compensate for over- winter kill and colony collapse disorder, but to respond to the increase in demand from farmers for pollinators for their crops and from the demand for more honey. Honey production increased from ~29,500,000 kg to over 41,000,000 kg between 2008 and 2012 (Agriculture and Agri-Food Canada 2013). It is also true, however, that for the majority of species, we don’t know very much about the habitats they depend on, their interdependencies with other species, the trends in their populations, or how changes in the environment affect them. This booklet is the story of the pollinators as we know it, what we know about why they are important to agriculture in Canada and some ideas on how we think they can be protected.
Link to entire document: Native Pollinators and Agriculture in Canada (AAFC publication)