Destructive human driven changes to the environment have adversely affected biodiversity on our planet. Pollinators in particular face many challenges associated with habitat destruction due to human activities. Especially in North America and Europe, studies have shown that the abundance and diversity of many wild pollinators has been in decline over the past decades. Agriculture and industrial development in general have reduced the amount of suitable habitats available to wild pollinators by reducing floral abundance and diversity across the landscape. This has a detrimental effect on pollinators as many of these insects need to feed on nectar and pollen from multiple species of plants to reach optimal fitness. A pollinator that has access to only one or a few types of flowers may be deprived of essential nutrients. This compounds the difficulty they face from a loss of habitats. Modern farming practices that use insecticides have further impacted insect pollinator populations which may be exposed to adverse and potentially fatal effects from these treatments. These chemicals can be found in the pollen and nectar of plants exposed to systemic pesticides. For many pollinators, these toxic chemicals can be deadly upon contact or ingestion. Neonicotinoids are a class of insecticides that have come under increased scrutiny for the detrimental effects they have on pollinator populations. Neonicotinoids make up about a quarter of worldwide pesticide use because they are considered safe for vertebrates yet deadly to insect nervous systems. Many are also applied to the seed of the crop plant and are taken up by the plant through the roots. The chemicals are then transported to various plant tissues which can include the nectar and pollen on which pollinators feed. While neonicotinoids have fewer detrimental effects on some non-target organisms compared to older generations of insecticides. These chemicals still substantially impact the viability of pollinator populations. The levels of neonicotinoids in agricultural settings are typically not enough to kill pollinators like honey bees but they can produce subtle effects that we may not instantly recognize. Neonicotinoids may disrupt an insect's behaviors and ability to learn which in turn impairs their ability to return to their nest site or find mates. At high concentrations like those applied to ornamental plants, neonicotinoids can easily kill pollinators. Pollinators have an important role in crop production. About 10 percent of crop species would not be able to produce fruit without animal pollination. In fact, animal pollination alone contributes anywhere from 230 to 570 billion US dollars to global crop production markets every year. Global food production would be substantially decreased without the pollination services provided by animals especially insects. Both wild and managed pollinators contribute to global crop production. Wild pollinators occur naturally in an ecosystem while managed pollinators are controlled in some way by humans. The activity of wild pollinators alone would likely not be sufficient to sustain modern agricultural yield. The most recognizable managed pollinators are bees. Bees have abandoned the predatory lifestyle of their wasp ancestors in favor of foraging on pollen and nectar. Humans have managed bees for millennia. Honeybees are generalist pollinators and were the first insect pollinators to be domesticated as depicted in 4,500 year old ancient Egyptian art. Though there's evidence they may have been domesticated as early as seven thousand years ago. Honeybees are a good example of managed pollinators that are essential to the widespread cultivation of a variety of important crops such as almonds, apples and even canola which is a key part of the agricultural landscape in the Prairie provinces of Canada. Although honeybees are important pollinators. They were originally reared for the nutritious carbohydrate they produce for their colonies honey. We will expand on beekeeping for honey production in the next lesson and even see some local beekeepers in action. Honeybees are not the only species of bee that had been domesticated by humans. Bees in the genus Bombus commonly called the bumblebees were first domesticated in the 1970s to pollinate greenhouse crops. Today several species of bumblebees are reared commercially. Bumblebees live in small colonies that produce little honey, so they're kept only for pollination. Bumblebees have a unique foraging behavior called buzz pollination in which the bees rapidly contract their flight muscles to vibrate pollen loose from the flowers they visit. Some plants like tomatoes and sweet peppers have pollen that can only be shaken loose by these vibrations or a very strong breeze. In greenhouse production, these plants rely solely on buzz pollinators as wind pollination is not available. Although they are sometimes used for outdoor crops, bumblebees are primarily used in greenhouses where they're small colony sizes better match the space available than honeybee colonies which would be cramped. Another type of bee domesticated by humans is the Alfalfa Leafcutter Bee, Megachile rotundata, a type of solitary bee which does not live in colonies. Leafcutter bees are used in the alfalfa industry because they nest gregariously and pollinate alfalfa flowers more efficiently than honey bees. This is because when an insect pollinates an alfalfa flower, the plants reproductive organs are tripped and hit the insect in the face. While honeybees learn to avoid this, leaf cutter bees don't seem to mind. A species of Mason Bee, Osmia lignaria is also a solitary leaf cutter bee the nest gregariously and has no issues exploiting man-made nesting sites. Mason bees are superior pollinators of fruit trees compared to other bees because they tend to visit flowers only a short distance from their nesting site which makes it easy for us to direct them to flowers we want them to target. They have also been shown to have a preference for the flowers of tree Fruits. So we're not likely to explore other plants and ignore the fruit trees. Additionally, mason bees have high levels of activity during the flowering period and a short flight season. Meaning the application of insecticides can easily be timed to minimize the bee's exposure to harmful chemicals. These factors combined make mason bees excellent pollinators for tree fruit production. In this lesson, we examined some challenges that pollinators face as a result of human activities. We learned about the economic significance of pollination and the impacts it has on modern agriculture. Finally we looked at some of the most important managed pollinators, the bees. With this knowledge about the process of pollination, you'll be prepared for a next lesson as we dive into the topic of epi culture, the human maintenance of honeybee colonies.
