Bumble Bees and Odor Pollution

Bumble bee and lawnmower

This morning they were mowing the lawn in my condominium. Wanting to leave the nerve racking noise behind, I headed for my favorite wildflower garden at Pennypack Ecological Restoration Trust. Instead of escaping the roar, I was treated to another dose of lawn mowing there. The weather was perfect for observing pollinators, so I stayed despite my discomfort.

Bumble bees were going about their business, gathering supplies for their brood, apparently unconcerned by the cacophony. I would like to think that they are equally immune to the fumes of gasoline, but suspect that it isn't so. When the noise stopped, I wondered: how long do the fumes remain? How far do they reach? How do they affect pollinators?

Pollinators need odor cues to find their food. Flowers emit scents to entice their favorite pollinators. These aromas are carried by the breeze, creating trails that bumble bees pick up in their wanderings. Studies show that it takes them longer to find these trails when gasoline fumes are present. It may not be apparent to observers, but lawn mowing impairs the productivity of bumble bees and other pollen seekers. Needless to say, car traffic has the same effect.

Now, you can hear the sounds of nature

References

Air Pollution: Floral Scents Going Off the Air?

Air pollution modifies floral scent trails. Sciencenews.

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2017

Monarch Butterfly, a Case of Mistaken Identity

Male monarch butterfly

© Beatriz Moisset

 A few days ago, I arrived at my favorite native flower garden at Churchville Nature Center with my camera, looking for pollinators as usual. A mother, also with a camera hanging from her neck, was visiting the garden with two children.

Black swallowtail caterpillar on fennel

© Beatriz Moisset

Milkweed tussock moth caterpillar

on common milkweed

© Beatriz Moisset

She pointed at a fuzzy, hairy, colorful caterpillar eating milkweed leaves. "Look at the monarch butterfly caterpillar," she said to the kids.

I couldn't stay quiet, "It is a tussock moth caterpillar," I explained.

"Oh, yes," she saved face by adding, "it will turn into a large moth, the tussock moth."

Later, she moved to a fennel plant and announced: "this is the plant that monarch caterpillars need for food."

The real thing, monarch caterpillar on common milkweed

© Beatriz Moisset

Should I have corrected her again? I would have to explain that monarchs feed only on milkweeds. Black swallowtails are the ones that need fennel. I simply walked away shaking my head.

Monarchs, monarchs, monarchs! I thought. How often people mistake anything else for monarchs?

Tiger swallowtail

© Beatriz Moisset

Just a few days earlier, a gentleman photographer at Pennypack Nature Center was busy snapping shots of something I couldn't see at the time. "There is a monarch right there." He pointed at a gorgeous large black-and-yellow striped butterfly with trailing tails on its wings, nothing like the orange and black monarch.

"It is a tiger swallowtail," I told him.

Fritillary butterfly on butterfly weed

© Beatriz Moisset

Then, I remembered all the times when people look at my framed photo of a fritillary butterfly and ask me if, or even tell me that, it is a monarch. All this sounds like Elvis Presley's sightings.

From pandas to dolphins to monarch butterflies: some animals become iconic. The monarch butterfly is, perhaps, the most iconic of all insects. Entomologist Marlin Rice (Iowa State University) referred to the monarch as the "Bambi of the insect world." This spectacular butterfly acquired its fame, in part due to a movement devoted to preserve the monarch and its remarkable migration. The movement is sponsored by websites such as Monarch Watch, the Monarch MonitoringProject, and a few others listed in the Walter H. Sakai's website. They are all worthy causes that engage the public; these projects can use the income generated by all the publicity.

I applaud the efforts of these organizations. At the same time, I wonder: A poster child is valuable if it raises awareness of a broader issue. The ecological importance of the monarch butterfly is that it is one of many species at risk because of human-caused habitat degradation. Other species may not be as appealing as the poster child, but they deserve our attention, too.

Red admiral, sometimes mistaken for a monarch

© Beatriz Moisset

The real thing, monarch butterfly on common milkweed

© Beatriz Moisset

Milkweeds, Monarchs and More: The Milkweed Community 
List of articles
Beginners Guide to Pollinators and Other Flower Visitor

© Beatriz Moisset. 2013

Lady Beetles. Not all are Welcome in the Garden

Asiatic Lady Beetle (Harmonia axyridis).

It poses a threat to native ones and it is a nuisance

when it gathers in large numbers

in winter in human habitations

………

 As I discussed in Native Plants and Wildlife Gardens on July 7th, not all ladybugs or lady beetles are beneficial. Some have been introduced from other lands and create trouble for the native species. Moreover, the sale of lady beetles as biological controls deserves thorough examination. You may be spending money for nothing or, worse yet, doing harm rather than good (Ladybugs,Lady Beetles or Ladybird Beetles. How Good are They?)

Mexican bean beetle (Epilachna varivestis). Stephen Ausmus. USDA

 Here are a couple of lady beetles which will surprise you. Not all lady beetles feed on other insects. A few feed on plants and may even be pests. The Mexican bean beetle (Epilachna varivestis) is just as cute as some of the most beloved lady beetles. Sadly it feeds on beans, peas and other plants of the pea family. The only consolation is that it also likes to eat that dreadful Japanese invasive plant, Kudzu.

Alfalfa Lady Beetle (Subcoccinella vigintiquatuorpunctata)

Luis Miguel Bugallo Sánchez/ Wikicommons

………

I also want to mention another pretty one, the Alfalfa Lady Beetle (Subcoccinella vigintiquatuorpunctata). It was introduced from Asia and feeds on alfalfa and an assortment of plants, such as bouncing Bet and campion. 

Another introduced species

 Seven-spotted Lady Beetle (Coccinella septempunctata)

………

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

Rainy Days Pollination Blues!

 Guest post by David L. Green, retired commercial bee keeper, former editor of small newspaper, teacher. You can visit his website and his blog

Partially pollinated cucumbers. © Dave Green, 2013

With seven inches of rain in five days, bees had very little time to work. They delivered enough pollen grains so that the cucumbers did not abort, but not enough to flesh them out.

The one at left is a total lack of fertilization of the seeds at one end - that meant that the flesh did not grow, and the cuke had a "tail." Three more are slightly better. The one at the bottom has few of the incipient seeds fertilized in the middle, giving a waist to the cuke. These poorly pollinated cukes grow slowly and quickly get tough, sometimes bitter, as well.

If bee populations are normal, this problem should straighten out when the weather is more suited to bee flight. If you get very many like this in good pollination weather, you have a shortage of bees, and may need to work on increasing bee populations or hand pollinate.

My garden is pollinated by a mix of bees, with the bulk of the workload carried by bumblebees and honey bees, but we also have green sweat bees, squash bees, digger (Anthophora) bees, tiny Ceratina bees, and leaf cutter bees doing some of that work.

To make a perfect cucumber, you need to get almost all of the incipient seeds fertilized. That requires two grains of pollen - one for the embryo and one for the seed coat, so each perfectly pollinated cuke represents several hundred grains of pollen delivered to the flower.

A lot of folks think that, if they see a bee in a flower, that pollination is accomplished. But it's not an on/off switch. It's a progressive thing. It takes many bee visits to deliver all the pollen needed for multi-seeded fruits.

Every year, more and more gardeners report the symptoms of lack of pollination in their gardens. The problem seems to be accelerating.

It represents one of our most urgent environmental problems - pollinator decline. Our bees are disappearing. Some of that is due to habitat loss; some due to monoculture and its feast or famine pattern of intense bloom, followed by barrenness; some is from new diseases and parasites; but the worst and most difficult problem to solve is the loss caused by pesticides.

When cotton blooms, bees focus on those nectar-rich blossoms, and drop by the millions when the cotton is sprayed. In July clover is in full bloom in the orchard floor, and more millions of bees die when the fruit is sprayed. Community mosquito sprays are supposed to be applied when bees are not working, but this time limit is very poorly observed, and many more bees are dropped from applications done when they are out. And many gardeners plaster Sevin dust all over their gardens without thought of the bees.

All four of these cases I mentioned are illegal applications, because the label directions forbid them, but label enforcement is rare and usually amounts to a slap on the wrist, if anything.

So, if we do not begin to protect our pollinators - we lose much of the vitamin C (fruits) in our diet. Food costs will rise; only the rich will be able to afford many of the most nutrient-rich foods we have. We are left with grains that do not need bees - but remember that "man shall not live by bread alone."

© Dave Green, 2013
Retired pollination contractor

List of Articles

Beginners Guide to Pollinators and Other Flower Visitors

Native Bees, Honey Bees and Natural Areas

Spring beauty bee © Beatriz Moisset

It is common practice for nature centers to have a beehive. Often, a glass wall allows observation of the colony's busy life, seldom failing to catch the eye of visitors. This serves an educational purpose by providing a great opportunity for a behind-the-scenes peek at the private lives of honey bees. Thus, visitors learn about these useful insects and their role as crop pollinators.

Honey bee © Beatriz Moisset

Sometimes I wonder if we are delivering the right message. The purpose of nature centers is to protect natural wildlife and to promote conservation of natural resources. This is clearly stated in many of their mission statements. Honey bees and chickens are domestic animals. They are both important to agriculture. However, we don't keep chickens at the bird feeders to teach about birds. Do we need honey bees to teach about insects?

Nowadays, agriculture relies heavily on honey bees; however, we must bear in mind that honey bees were introduced to this continent by Europeans a few hundred years ago. Until then, all pollination was accomplished by native pollinators, more than 4,000 species of bees and many other insects, such as flies, moths, wasps and even beetles, as well as some birds and bats.

Jack-in-the-pulpit © Beatriz Moisset

Fungus gnats © Beatriz Moisset

Native plants didn't need honey bees then, and they don't need them now. A few examples should suffice. In early spring a number of delicate little flowers carpet the forest floor. They are in a rush to take advantage of the sunlight during the absence of foliage and don’t last long. Thus, they are called "spring ephemerals." None of them is visited by honey bees. In fact, many resort to highly specialized pollinators which have been around for as long as the plants themselves. Skunk cabbage and Jack-in-the-pulpit are pollinated by flies. Spring beauties and trout lilies are visited by an assortment of bees and bumble bees; but get help, in particular, from their own specialized pollinators, the so called spring beauty bee and the trout lily bee respectively.

Azalea bee © Beatriz Moisset

Shortly after, when azaleas bloom another set of specialists comes into service, the buzz pollinators. These are experts at shaking the pollen out of the flower stamens. One of these experts is the azalea Andrena bee. Its name needs no explanation.

So, what are honey bees doing in the meantime? They devote their time to the nectar and pollen of willows and maples. Thus, honey bees make use of these trees, but the trees themselves benefit from an abundance of native pollinators and don't need the extra help. Honey bees also gather pollen from hazelnuts. This is good for the bees but doesn't help the trees in the slightest because they are wind-pollinated.

Magnolia and mordellid beetles © Beatriz Moisset

Honey bees don't pollinate azaleas or rhododendrons. They also ignore dogwoods. As for magnolias and their close relatives, tulip trees, these plants are primarily pollinated by beetles and flies, all of them native. Honey bees are more inclined to visit generalist flowers, the ones receptive to a wide range of pollinators. Therefore, native pollinators are all that the flowers need.

Another problem with honey bees in natural areas is that they may contribute to the spread of non-native plants by pollinating them preferentially. They also may compete with native pollinators for floral resources.

Tricolored bumble bee © Beatriz Moisset

In summary, native plants and native pollinators are members of a complex community. They have adapted to each other and work well together. Honey bees, while important to agriculture, are not needed in natural areas. The only justification for keeping beehives at nature centers is to use them as a gate to the understanding and familiarization with insects and their usefulness. If the visitor leaves the nature center as ignorant of native pollinators as he was when he came in, then the center has failed to deliver the most valuable message of the bees.

It is imperative that naturalists and educators at nature centers with beehives devote time to informing the public about native pollinators and their significance to native plants. Posters with this information would also be helpful.

Augochlora pura © Beatriz Moisset

Tom Bain presents some good suggestions in his blog "GeoEcology. Earth and life through time..."

 "There is an essential piece missing from the typical presentation about pollination in many nature centers, that is the discussion of native pollinators and their essential continuing role in native and not so native ecosystems. Each presentation about honey bees should be accompanied by a hands-on activity to plant native plants that are partners to native pollinators, or the construction of simple solitary bee houses from dry bamboo canes or wood blocks. We would make progress if our children earned great take-home's like solitary bee bundles in place of coloring-in honey bee illustrations; and, planting native seeds to grow purple coneflower or other natives in place of marigolds, etc. A little effort and a subtle change in emphasis would shift attention to native pollinators."

List of Articles

Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2013