Pollination and Pollinators

With spring time, come allergies for many. The air is full of pollen from various plants, as the process of pollination has begun. People can't escape the pollen; as a result they breathe it in. For some, the pollen causes no issues, for others their body attack the pollen grains, resulting in running nose, itchy eyes and throat, difficult breathing and sneezing. As the summer goes on the allergies begin to taper of. Pollen allergies may be make life miserable for a bit, but life without pollen could be just as miserable. This module is all about flowers, the process of pollination, important of pollination and pollinators. So take some Benadryl and enjoy the beauty pollination add to our lives. 

Lesson 1- The Pollination Process

In order to understand the process of pollination, it is important to be familiar with the parts of a flower, where they are located and the role they play.

Part Role
Stamen (Male reproductive parts) Anther Contains pollen sacs
Filament Stalk of anther
Pollen Fertilizes the ovule

Carpel (Female reproductive parts) 

 -all carpels make up the pistil

Stigma covered in sticky substance that pollen grains adhere to 
Style raises the stigma away from ovary
Ovary protects ovule; becomes fruit after fertilization
Ovule fertilized by pollen to become seed
Petal attract animals to the flower; some have guideline or are scented
Flower Stalk supports and elevates flower
Receptacle flowers attachment to stalk; may become part of the fruit, i.e. strawberries
Nectary were the nectar is found
Sepal offers protection to the flower as it develops from a bud

Diagram of a Flower

During pollination, pollen grains from the anthers are moved to the stigma. Some flowers are able to self-pollinate, where the pollen grain produced in the stamen of the flower can pollinate the ovule in the ovary of the flower. Other flowers have to rely on animals and the wind to help them cross-pollinate or pollinate other flowers of the same species. Once the pollen grains adhere to the stigma they travel down the style and into the ovary. The ovules and pollen grains fuse, fertilization occurs and seeds are the result.

The petals of the flower fall off and only the ovary is left. The ovary develops in to a fruit.  A fruit is any structure that encloses and protects a seed, so not only are apples, plums and oranges fruit but so are acorns, "helicopters," hazelnuts, etc. When you eat a fruit, you are eating the ovary of the flower. 

Angiosperm - flowering plants; seeds or ovule are enclosed during fertilization

Gymnosperm -mean "naked seeds"; conifers, cycads, ginkgo, gnetales

Lesson 2 - Pollinators

Bees - there are over 1000 native species to Canada

Honeybees are non-native to Canada. They were brought to the country from Eurasia for domestication for honey production. All the "wild" honeybees in Canada are from hives that they escaped from over the years. Bees in the wild build their hives in forests or wooded shelters. During the winter the bees generate heat to keep it warm.

There are three classes of honeybees; workers, queens and drones. Workers are females that are not sexually developed. There are roughly 80000 worker bees per hive. The queen bee is the only reproductively mature female in the hive. Drones are the male bees. There are several hundred drones in the hive during the spring and summer.

The worker bees are the bees we always see. They forage for food, which is nectar and pollen. They are responsible for building and protecting the hive, cleaning and circulating air by beating their wings and performing other societal functions. 

The queen regulates the hives activity by producing chemicals that  guide behaviour of the other bees. She lays roughly 2000 eggs per day. The eggs are fertilized by the drones. Unfertilized eggs develop into male bees. If the queen dies the workers create a new queen by feeding one worker a special diet referred to as "royal jelly." The worker develops into a fertile queen.

When winter comes the drones are expelled from the hive. The hive goes into survival mode. The workers and queen feed on stored honey and pollen. They all cluster into a ball to conserve heat. The workers are responsible for feeding the larvae and a new generation emerges in the spring.

In Eastern Canada, wild honeybees have almost been exterminated as a result of two types of parasitic mites that infest hives. The mites are spreading to domestic hives. Along with the parasite invasion, bee populations are affected by habitat loss, pesticide use and bacterial diseases that are moved from hive to hive.  

Bumblebees are larger, fatter and have a furry look when compared to honeybees,. There are approximately 24 species of bumblebees that are native to Canada. They nest underground and the queen is the only one to overwinter. In the spring the queen lays her eggs inside her nest. The males will fertilize the eggs and leave to forage on their own. The eggs left unfertilized develop into male bumblebees.  The queen will forage nectar and pollen to feed the larvae. The first worker bees to develop will take over the duty of feeding the larvae.

Bumblebees are effective pollinators in small areas as they tend to by small in numbers. The tongue size varies with different species therefore a variety of flowers may be pollinated.

Wasp

Yellow-jacket wasps are native to Canada. They are very social wasps that are found in colonies. Yellow-jacket wasps are named for their large, shiny black and yellow bodies. Female yellow-jackets are the only ones that can sting. Their stinger is known as an ovipositor, or egg laying structure. Unlike bees that lose their stingers after stinging, wasps can sting multiple times. 

The social structure is similar to the colony of honeybees, with sterile workers, a queen and drones. The fertilized female or queen is the only wasp to overwinter, the rest die-off. Once spring arrives the queen builds a nest using wood fibres and saliva. It is attached to trees, eaves, wall cavities or placed underground. Once the nest is prepared the queen will lay her first set of eggs. The queen will remain in the nest with the larvae and feed them chewed insects. Once the first workers develop they take over caring for the larvae. The queen spends a majority of her life laying eggs. Near the end of the summer males, which develop from unfertilized eggs, will mate with a female. By winter the old queen dies and the mated females leave to hibernate under soil.

Yellow-jacket wasps are not as effective as pollinators as bees because they lack hair, but there are big numbers of them. These wasps are carnivorous; they eat insects and carrion. Although nectar is not a big part of their diet, it is of the insects they eat. Therefore will hunting for prey, which is usually feed on nectar of a flower, pollen is spread from flower to flower.

Paper wasps are named for the paper nests they build. These very common wasps are medium sized; they have a small head and a slender body that is primarily black with a few yellow strips. Paper wasps are social, live in colonies and will sting if their nest is disturbed. 

These wasps build their nests out of wood fibres collected from dead wood, wooden structures or plant stems, mixed with saliva. The nests are cone shaped and hang upside down from tree branches or house eaves. 

The lifecycle of a paper wasp is similar to yellow-jackets. The queen lays eggs for most of her life, and then dies when winter comes. Mated females leave the dying nest and find a site to live. During the larvae form the food of choice is insects. Adults feed on nectar and therefore help with pollination

Bald-faced Hornet is not a true hornet; it is actually a large, black and white wasp. This wasp is only found in North America. It is closely related to the yellow-jacket wasp. These social wasps live in colonies. The queen starts the colony by building a nest and laying eggs; one or more broods of workers are produced. The workers have a large patch of white on their face; bald-spot. Like with the other wasps, only the mated females will survive the winter.

The nests of the bald-faced hornet are large, grey structure with a point end. It is made from paper-like material (wood fibre and saliva) and hangs from trees, bushes, low vegetation or buildings. 

These wasps will sting when disturbed, can sting repeatedly which may be fatal. They feed on nectar and insects that are attracted to flowers, usually the damaging ones. 

Now bees, wasps and hornets get a bad rap because of their sting. Many people take off in the other direction when they encounter one of these stinging insects. There is no problem with that. Getting stung by a wasp, hornet or bee is no fun and in some cases could be fatal. But we must appreciate the work they are doing for us. 

Lesson 3 - More Pollinators

Flies

Hover flies are native to Canada and get their name from their ability to hover and dart to wild flowers. Small to medium sized flies can be black and yellow or black and orange. They have a narrow waist like a wasp and will mimic stinging but they are harmless.

When laying their eggs, hover flies will lay them near aphid colonies. The larvae will feed in insect pests including aphids, which annually damage crops, scales and caterpillars. The long tongue of a hover fly combined with their small size makes them successful pollinators. These flies are most active at the beginning of July. 

Bee flies are native to Canada as well. They resemble bumblebees with their hairy brown, black or yellow bodies. Bee flies are large, have long legs and will spread their wings open when resting. They have long proboscises that are ideal for probing nectar. Bee flies are agile and faster than bees. They emit a high pitch sound when flying. The larval form of bee flies act as parasites; eggs are laid in hosts nest, the larvae with eat eggs, larvae and grub stages of beetles, bees, wasps, butterflies/moth, caterpillars and  grasshoppers.

Bee flies do not eat pollen but are moderately good pollinators when they are adults.

Birds

Ruby-throated hummingbirds are small birds with slender, slightly downward curved bills and short wings. They have bright emerald or golden green on their back and crown with gray-white underparts. Males can be distinguished by their red throat. These birds are quite agile; they can quickly change direction. They have the ability to fly full out and stop in an instant, hang motionless in midair and adjust up, down, sideways and backwards. Hummingbirds have really short legs; too short to walk or leap, instead they shuffle.

Ruby-throated hummingbirds are the only hummingbirds found in PEI. They are important pollinators as they fed on nectar from red and orange tubular flowers. Their long beaks and tongues allow them to feed from many flowers that other pollinators cannot. The pollen grains stick to the side of their beak; when the birds fly to another flower of the same species to feed pollination will occur. Male hummingbirds will aggressively protect this flowers it feeds from. They also fed on mosquitoes, gnats, fruit flies, small bees and spiders.  

Nests of hummingbirds are the size of a large thimble. They build them directly on top of a branch; not in a fork. The nests are usually made of thistle or dandelion down that is held together with strands of spider silk or sometime pine resin. The outside of the nest is covered in lichen and moss. It will take 6 to 10 days to make the nest. It usually measures 2 inches across and 1 inch deep.  

A female hummingbird will lay 1 to 3 eggs per clutch. They will brood once or twice during the mating season. Their white eggs are tiny, weighing about half a gram.

Lesson 4 - Flowers

Plant structures are designed to attract pollinators. The petals of a flower act as a landing platform for the pollinator. The lines or markings on the petals help guide the animal to the nectar, making them rub up against pollen grains. The aroma given of by flowers attracts pollinators. Most often the odour is a sweet and pleasant one, but there are some exceptions...for example the Rafflesia flower, found in Indonesia, gives of the scent of "rotten meat', which attracts its pollinator; the fly. During the day, flowers that are pollinated at night will close so unwanted animals can not steal the nectar; day pollinated flower close during the night. 

Hummingbirds appear to be most attracted to flower with red petals. Most red petaled flowers are loaded with carbohydrate-rich nectar, providing the pollinator with instant energy.  Insects do not see the colour we see, instead they see UV light. When a flower is looked at under UV light, the reproductive parts are dominant. 

Some plants and pollinators have evolved together, referred to a coevolution, so that they are highly dependent on the other for food, in the pollinator's case, and reproduction, in the plants case. While coevolution may prove to be beneficial, it can be risky; the extinction of one member, may lead to the loss of the other. 

Explore important plant-pollinator relationships, discussing symbiosis. 

Symbiosis is the close, often long term, relationship between different biological species. There are three types of symbiotic relationships:

Parasitism: one organism benefits, while the other is harmed. 

Commensalism: one organism benefits, while the other is not harmed, nor does it benefit.

Mutualism: both organisms benefit. Pollination is an example of a mutual relationship.

Lesson 5 - A World without Pollinators: Importance of Pollination

Pollinators are disappearing for various reasons, with habitat destruction, pesticide use and parasitism/disease being at the top of the list. A world without pollinators would be a world without many of the foods humans rely on. It has been estimated that 1 of every 3 bites is a direct result of pollination. In the United States, bees and other pollinators produce $20 billion worth of product each year. Without pollination a lot of the food we rely on today, would not be available.

We would not starve if pollination was to halt, but many of the essential foods in our diets would disappear, such as fruits and vegetables. These are the foods we rely on for vitamins, fibres and important oils. Instead our diets would consist mainly of grain crops, cereals and rice which rely on self-pollination or wind. 

The honey bee population has suffered a major decline in recent years. Colony Collapse Disorder, a phenomenon where worker bees go out in search of nectar and fail to return, has become a common event. 

How can we protect our pollinators?

  • reduce or stop the use of pesticides
  • plant gardens with NATIVE, nectar-producing flowers
  • leave tree stumps, dead branches and rotting tree that are home for many organisms
  • don't destroy bee hives, instead contact a local beekeeper

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