Apr 212016
 

The lovely spring weather we’ve enjoyed this past week has caused an explosion of plant growth. Buds are swelling, grass is turning green, and a half-dozen species of wildflowers are in bloom. The blossoms are already attracting the first bees. Although I’ve witnessed this rebirth of nature over too many springs to count, the wonder of flowers and their pollinators never ceases to amaze. What better way to celebrate Earth Day than to take some time to understand and appreciate the extraordinary story of pollination and to think about what you can do to welcome pollinators to your garden or balcony.

A Monarch butterfly drinks nectar from a New England Aster - Tim Dyson

A Monarch butterfly drinks nectar from a New England Aster – Tim Dyson

To human eyes, flowers embody beauty and vitality. We rave about the colours, the shapes, the symmetry and, of course, the intoxicating scents. It’s therefore tend to forget that human beings are not the target audience for these alluring plant structures. Flowers have evolved for one thing only: to produce seeds and thereby assure another generation. The mechanism by which this occurs – pollination – is one of nature’s most fascinating phenomena and a crowning achievement of evolution. Yet, the beauty, intricacy and importance of pollination is often taken for granted, as is the role played by a host of pollinator species, many of which are in serious decline.

What is pollination?

To understand pollination, we need to reacquaint ourselves with the parts of a flower (see diagram). As with human beings, some flowers are either male or female. Separate male and female blossoms can be on the same plant – most often a tree or shrub – or on separate plants. A willow tree, for example, is either male or female, with only the female trees producing seed. Other flowers , known as “perfect” (like the one in the illustration), have both female and male structures. The latter produce pollen, which is the source of male sex cells and analogous to sperm in animals. Pollen production takes place in the anther at the top of the male flower part known as the stamen. The eggs (ovules), or female sex cells, are located in the ovary at the bottom of the pistil, the flower’s female part. At the top of the pistil, there is a sticky surface called the stigma – think of “stickma”. Pollination occurs when pollen grains are transported by the wind or on the body of an animal from the anther of one flower to the stigma of another flower of the same species.

The parts of a flower (Drawing by Judy Hyland)

The parts of a flower (Drawing by Judy Hyland)

The second step in the pollination process is fertilization. A flower becomes fertilized when a pollen grain on the stigma grows a pollen tube, which makes its way down through the style and into the ovary. Inside the pollen grain, male sex cells are then produced. These cells travel down the tube and fertilize the ovules. The fertilized ovules grow into seeds, and the ovary wall becomes the encasing fruit around the seeds. The next time you bite into an apple, take a moment to reflect that you are actually eating an apple flower’s ovary! Similarly, a milkweed pod is simply a ripened ovary containing seeds.

An analogous process occurs in conifers. Male cones – the small, delicate ones that litter the ground in late spring – produce pollen. They are yellowish when ripe, because of the pollen dust they contain. The pollen grains are carried by the wind and, by dint of their astronomic numbers, some come into contact with female cones. These are the familiar woody “pine cones” and contain ovules. The ovules are located under plate-like scales. The scales open temporarily in the spring to receive the pollen. They then close during fertilization and maturation. The scales re-open again at maturity to allow the seed to escape. Depending on the species, seed maturation takes 6–8 months in conifers such as spruce but from 18 – 24 months in most pines. Female cones are quite different in size and shape from one kind of conifer to the next.

Pollinators

Plants that rely on wind to move their male sex cells have light and dusty pollen. The male flowers often hang loosely and sway back in forth in the wind, which helps to release the pollen. Some, like those of poplars, oaks and birches, look like soft caterpillars hanging down from the stems. In most cases, these flowers lack petals, are dull in colour, and have no fragrance. There’s no need for the plant to invest in petals, bright colours and alluring scents since there’s no need to attract pollinators. Wind-pollinated flowers usually appear before the leaves come out, since evolution has “learned” that leaves would get in the way of effective pollen transfer.

A great many plants, however, depend on insects to transport their pollen, although hummingbirds and bats sometimes do the job. Collectively, these animals are known as pollinators. They visit flowers in search of food, which can be nectar or the protein-rich pollen itself. Bees intentionally collect both pollen and nectar. They feed the pollen to their developing offspring. Butterflies, moths and hummingbirds, on the other hand, feed only on the nectar. Markings in the flower sometimes guide the pollinator to the nectaries where the sweet liquid is located. As they feed, the pollinators brush up against the stamens and pollen inadvertently adheres to their body. Then, when they move on to another flower, the pollen is accidentally transferred to the sticky top of the pistil. Animal-pollinated plants produce pollen, which is too heavy to be moved very far by the wind. This is why goldenrod pollen is not the cause of hay fever. Rather, the light, wind-borne pollen of ragweed is the culprit.

Evolution

Flowers have evolved in remarkable ways to attract pollinators, which in turn have evolved in response to changes in the plants. In other words, each organism has developed adaptations, which work to its own benefit. For instance, flower evolution has produced an amazing array of colors, markings, shapes, fragrances and even different flavours of nectar. Some plants like skunk cabbage even go further. Skunk cabbage could almost be described as “warm blooded” because they generate heat. The warmth, along with the plant’s putrid smell, attracts early spring insects, which are looking for food and a spot to warm up. In exchange, the insects end up accidently pollinating the plant.

The flower-pollinator relationship is especially interesting when it comes to bees. Many species are attracted to the colours blue and yellow, to bilateral symmetry (e.g., the shape of a daisy) and to flowers with lines leading to the nectar. Consequently, over millions of years, many plant species have evolved these characteristics in order to attract bees. The bees, in turn, inadvertently distribute the plant’s pollen grains and optimize its reproductive success. It doesn’t stop there, however. Simultaneously, the plants have exerted pressure on the bees by favoring behavioural and structural traits that allow these insects to take advantage of the nutritional rewards offered by the plant. Hairiness is one such trait. Hairs all over the bee’s body actually have a strong positive charge with attract the negatively-charged pollen grains. This kind of relationship is known as co-evolution.

Honey Bee - Wikimedia

Honey Bee – Wikimedia

Richard Feynman, a famous American physicist, had an artist friend who said that a scientist can’t appreciate the beauty of a flower the way an artist can. His artist friend felt that by studying a flower scientifically and ‘taking it all apart’, the flower loses its beauty. Feynman disagreed. He said that, as a scientist, he sees more beauty and wonder in a flower – not less – than even the most sensitive artist sees. Scientists can imagine the cells, the complicated actions going on inside, and the fact that the colors evolved in order to attract insects to pollinate the flower. In other words, scientific knowledge only adds to the excitement, the mystery and the awe of a flower. The more you understand the biology of plants and pollinators, the more your appreciation grows, starting in your own garden.

Peterborough Pollinators

      How do we empower citizens to protect pollinators and, in doing so, create, restore and celebrate natural environments in the Peterborough area? A group of local citizens has set out to answer this question. Peterborough Pollinators is working to encourage the creation of pollinator gardens throughout the city. Not only will these gardens help pollinators, but they will also bring greater food security, sense of place and community development to our neighbourhoods and daily lives.

We’ve all heard about the mysterious decline of honey bees. However, other bee species are also declining, largely because of habitat loss. You can make a big difference just by creating a bee- and butterfly-friendly space in your garden. To learn more about Peterborough Pollinators, take part in upcoming workshops, access resources and sign up for their newsletter, visit peterboroughpollinators.com Resource information is also available at   peterboroughdialogues.media/pollinators/

 

Jul 032014
 

One of the joys of tuning into nature is discovering the many amazing organisms that exist right under our nose and often go unnoticed until someone points them out. When it comes to flying under the radar, there are few better examples than Ontario’s native bees. Susan Chan, a pollination biologist and expert on native bees, lifted the veil on this fascinating world when she spoke recently to the Peterborough Field Naturalists. Susan is the program manager of an organization called “Farms at Work” and is working with regional farmers and landowners to protect and encourage these wild pollinators.
As Chan explains in her informative handbook “A Landowner’s Guide to Conserving Native Pollinators in Ontario” (available at Avant-Garden Shop) bees are keystone species in that they have a disproportionately large effect on the environment relative to their abundance. Thanks to their role as pollinators, bees provide an essential link in the reproductive cycle of plants and therefore help to feed and sustain all living things. Simply put, they allow us to eat. Anything that consumes seeds, fruits or vegetables, depends on pollinators. This includes not only human beings but countless other species as well.
A few words about Honey Bees is a logical starting point to any discussion of pollinators. Native to Europe and Asia, Honey Bees are domesticated insects in much the same way that cattle are domesticated mammals. They have been bred over the centuries to serve humans. However, it now appears that much of the pollination work that is normally attributed to Honey Bees may actually be carried out by native bees and almost go unnoticed. Susan is therefore hoping to give our native bees the recognition, respect and protection that they deserve.

Common Eastern Bumble Bee nectaring - by Margot Hughes

Common Eastern Bumble Bee nectaring – by Margot Hughes

Pollination
In order to tell the story our native bees, we need to begin with the story of pollination itself. Its purpose is simple: to allow plants to set seed in their ovaries. First, a little basic botany is in order. The anther, or male part of the flower, produces pollen. Pollen from wind-pollinated species like grasses and many kinds of trees is light and dry and therefore easily dispersed through the air. However, pollen from insect-pollinated plants like fruits and vegetables is oily and heavy, so that it will adhere to the bodies of pollinators. The female part of the flower consists of an ovary, which contains ovules. The ovary is connected by the style to a sticky structure called the stigma. At the base of most flowers there is also a nectar-producing organ called a nectary.
Simply put, pollination is the transfer of pollen from the anther to the stigma, usually between two different plants of the same species. When a pollinator such as a bee brushes up against the stigma, pollen on its body may adhere to the stigma’s sticky surface. The pollen grain will then grow a tube down through the style to the ovary, where it fertilizes an ovule and produces a seed. Not surprisingly, there is a payoff for the insect, too. Nectar and pollen provide food for the bees – both for the adults and the larvae in the nest.
The best insect pollinators are the hairy ones, and the hairiest of the insects are the bees. Their hairs pick up and hold on to pollen. Our native bees go one step further, however. They offer the added benefit of being active when Honey Bees – the “divas” of the bee world – don’t dare set foot outside the hive. Many of our native bees, on the other hand, are out at the crack of dawn, during cool weather and sometimes even in when it is raining. For example, squash bees become active at 4 a.m. when squash flowers open!

Bee-watching
So, who are the native bees? In eastern Canada, they are represented by some 400 species, grouped into five families. Of these, about 300 are important as pollinators. Unfortunately, most do not have common names, although they live and forage in fields and gardens throughout the Kawarthas. The five families are the Halictidae (sweat and pearly-banded bees), the Apidae (squash, carpenter and bumble bees), the Colletidae (cellophane and masked bees), the Andrenidae (miner bees) and the Megachilidae (leafcutter, orchard and mason bees). The majority of these bees are solitary, which means there is only one female per nest. In other words, most do not live in colonies. Nor do they sting, swarm or make honey. Bumble bees are the one exception. Numbering about 15 different species in Ontario, they can deliver a sting and they are colonial. However, the colonies only exist for one breeding season, and the amount of honey the bees make is minimal.

Halictid bee on Sundrop blossom - Drew Monkman

Halictid bee on Sundrop blossom – Drew Monkman

Although native bees can be found most anywhere there are flowers, identification to the species level is challenging. The only identification guide that presently exists is limited to the bumble bees. Entitled “Bumble Bees of the Eastern United States”, you should be able to download the PDF by going to http://bugguide.net/node/view/595902. Alternatively, you can contact Chan at sue@farmsatwork.ca and she will send you the PDF herself. This guide applies equally well to Ontario. Even the bumble bees, however, can be hard to identify. One reason is sexual dimorphism, which means that the male and female are often quite different in size and colouring. Queen bumble bees are large -think thumb-sized – and are the ones you see flying about in the spring. The small bumble bees that are so common in July and August are workers and are much smaller. Probably the most common species in the Kawarthas is the Common Eastern Bumble Bee. The thorax and thorax end of the abdomen are both pale yellow in colour. The rest of the body is black. You should also watch for the beautiful Tri-colored Bumble Bee. Two orange stripes on the abdomen make it quite distinctive.
For the other native bees, Chan suggests learning to identify them to the family or, in some cases, the genus level. Here are three easily recognizable varieties to get started. Most Halictidae bees are very small, often no larger than two grains of rice. Luckily, some are metallic green and therefore quite distinctive. I was able to find these quite easily in my perennial garden. If you grow squash, zucchini or pumpkins, you will likely see squash bees. In the afternoon, when the flowers are wilted, gently open the flower with your fingers. If you find a bee inside, it will be a male squash bee. Chan guarantees that “once you’ve met them, you’ll fall in love!” Approximately the size of Honey Bees, squash bees are grey-striped and have a somewhat flattened abdomen. In late summer and fall, you should be able to see miner bees on sunflowers and goldenrod. They have extremely hairy back legs and therefore end up with “pantaloons” of pollen on their legs. An excellent collection of native bee photos can be found at www.discoverlife.org/ Look under the Apoidea to find bees. BeeSpotter is another useful on-line resource for photographs. Go to http://beespotter.mste.illinois.edu/

Tri-colored Bumble Bee on goldenrod - Drew  Monkman

Tri-colored Bumble Bee on goldenrod – Drew Monkman

Native bees can be found most anywhere there are flowers. This includes perennial gardens and sunny meadows. Raspberry patches can be especially good, as can sunflowers. A great place to see bumble bees is at a blueberry farm in mid-May. Kelly’s Berry Farm north of Bancroft is one such location. The tallgrass prairie and Black Oak savanna at Alderville First Nation also has a great diversity of bumble bees.
Remember, too, that there are many bee look-alikes on flowers. Flower flies, for example, can look surprisingly bee-like. However, they have only two wings and hold them at an angle out from the body. Bees, on the other hand, have four wings. They are folded over each other and fit neatly across the back. Unlike flies, bees are also hairy. As for wasps, their bodies are narrow-waisted, slender and smooth.
Next week, I will look at the life cycle of native bees, why they are vulnerable and how landowners can protect and encourage these wild pollinators.

 

 

Sep 192013
 

Hedgerows  

Living here in the beautiful Kawarthas, we take for granted the familiar charm of rural hedgerows and the trees, shrubs and wildflowers that grow along them. Hedgerows – or fencerows as many people call them – are a common feature of agricultural lands, especially in the southern part of our region.  On an esthetic level, they provide a picturesque border to fields and, in doing so, contribute greatly to our sense of place. Just as importantly, hedgerows also provide important ecological services, including food and nesting sites for pollinating insects such as our native bees. Unfortunately, there is a war of attrition being waged on these important corridors of green in many parts of Ontario and increasingly so in the Kawarthas. Little by little, hedgerows are disappearing as the economics and technologies of farming change.  To see what this destruction  looks like in the extreme, one only has to take a drive through the expansive, hedgerow-less fields of Essex County and Chatham-Kent in southwestern Ontario.

Healthy hedgerow

Healthy hedgerow

Hedgerows and bees

Ontario is home to numerous species of native bees, most of which go overlooked. These insects are not the familiar European Honey Bees, nor are they wasps or other aggressive stinging insects. Native bees come in a wide range of sizes and colors, from tiny sweat bees less than a quarter of an inch long to much larger bumble and carpenter bees. Some aren’t even bee-like in appearance but may be dark brown, black, or metallic green and blue. Many species look like flying ants or flies. Most of our native bees are solitary, with each female creating and provisioning her own nest – often in the ground – without the help of sister worker bees.

                Because healthy hedgerows are home to a rich plant community, they provide crucial bee habitat. For example, hedgerow shrubs such as cherries, sumacs, lilacs, serviceberries, dogwoods, hawthorns and wild apple trees are a reliable and plentiful source of nectar and pollen in May and June, a time of year when many other plants have not yet flowered.   Along the edges of the hedgerow, you can usually find other important bee plants such as raspberries, blackberries, goldenrods, asters, clovers, milkweeds as well as numerous so-called weeds, many of which are bee magnets, too. Dandelion and coltsfoot, for example, are especially important to bees in early spring.

Hedgerows also provide essential nesting habitat. Dead trees, rock piles and Groundhog burrows – all common components of hedgerows – are especially important. Solitary bees, for example, actually nest in wood, while bumble bees often choose rodent burrows or the cavities created by rock piles to set up home. The pithy stems of blackberries and raspberries are a common nesting site for yellow-faced bees and small carpenter bees. A large number of birds also nest in hedgerows. These include Wild Turkeys, Eastern Kingbirds, Brown Thrashers, Gray Catbirds, Song Sparrows and Indigo Buntings – to name a few.  Birds and mammals also use hedgerows as corridors for moving through the countryside between isolated woodlots, since many species hesitate crossing an open field. This is of particular importance in areas where farming is more intensive, such as southern Peterborough County.

Hedgerows provide other services to farmers and rural residents, as well. They help to prevent loss of soil from fields, either through reducing wind erosion or through acting as a barrier to water-borne run-off. There is also research to show that removing fencerows and their attendant vegetation allows wind-borne, fertilizer-laden topsoil to blow into water bodies and thereby promote algae growth. Let’s not underestimate the cultural and aesthetic services that hedgerows provide, either. With their cedar-rail fences and frequent rock piles, they tell the story of the countryside and of our farming heritage. They also are an important element of the characteristic structure and pattern of the landscape in much of the Kawarthas and thereby help to root us in this particular part of Ontario. They shield us, too, from unsightly development and protect privacy.

 

Pollination

Although most of the staple grains (e.g., wheat, oats and corn) in human and animal food systems are wind-pollinated, the fruits, nuts, oilseeds, and many of the vegetables require a pollinator other than wind to maximize production and quality. In the past, agriculture has largely ignored wild pollinators and has depended almost entirely upon domesticated, non-native Honey Bees to provide pollination services for the crops grown on farms. However, as we know, Honey Bee populations are declining sharply. It is therefore critical to look to a more diverse population of pollinators to meet the pollination requirements of agricultural crops and especially to the native wild bees.

In a sweeping, 19-country study that came out last February entitled “Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance,” it was shown that wild pollinators are able to provide all of the pollination needed IF farmers cultivate and protect habitat. The authors found that wild insects pollinated crops more effectively; an increase in wild insect visitation enhanced fruit set by twice as much as an equivalent increase in Honey Bee visitation; and that pollination by managed Honey Bees supplemented, rather than substituted for, pollination by wild insects. The results suggest that new practices for integrated management of both Honey Bees and diverse wild pollinators will enhance crop yields. The take-away message from the study is that wild pollinator habitat needs to be conserved, especially at a time when pollinators are already in a downward spiral as a result of other threats such as pesticides. For more information on what landowners can do for pollinators, Google “A Landowner’s Guide to Conserving Native Pollinators in Ontario.”

Field stripped of hedgerows near Keene

Field stripped of hedgerows near Keene

Threats

Unfortunately, there is a growing trend towards removing traditional hedgerows. In Otonabee-South Monaghan Township, for example, some landowners are either removing hedgerows completely or clearing out the shrubs, grasses and wildflowers that grow there.  In the latter cases, they are simply leaving the large trees. According to one area resident, “This past spring, the chainsaws and excavators were going full-time, and it’ll start up again after the harvests. It’s horrifying.” Some local fields, such as many of those along County Road 2, west of Keene, are starting to look like the Canadian prairies.

Why is this happening? Removing hedgerows increases the size of the fields, making the sowing and harvesting of crops easier, faster and cheaper, especially for large, modern machinery. It can therefore increase yield and profits in the risky business of agriculture. However, it’s not just the bottom line that drives modern farming practices.  There are a host of other factors – demographic, social and technological – that compel farmers to make the most effective use of their time and to offset risk.

In the European Union, the Common Agricultural Policy offers greater incentives to farmers to protect and restore natural landscape features such as hedgerows. These incentives are in the form of subsidies for “protecting the environment.” If similar incentives existed in Ontario, maybe we would see less destruction.

Although traditional hedgerows still dominate on most farms in the Kawarthas, this may not be the case within a few years. Hopefully, rural landowners who might otherwise just go along with the trend towards removing hedgerows will have second-thoughts. Given all of the services that hedgerows provide – and even if they present a short-term inconvenience –  protecting them is one do-able step toward long-term agricultural sustainability.

 

Side-bar: Climate change rally

In order to get the attention of our politicians – and our neighbours – to the urgent problem of climate change, a Climate Change Rally will be held on Sunday, September 22,  from 11 a.m. until noon, at Millennium Park (at the corner of Water and King streets) in  Peterborough.  The Rally will feature great local speakers and an information tent.  Washboard Hank will inspire the children. Other musicians, such as Al Black, will join Hank to help all of us sing a global climate change song, The Rally organizer is the Peterborough chapter of For our Grandchildren (4RG).  Please consider giving an hour of your time to come to this important event and show our politicians that we want to see action NOW.