Content Background
Parts of a Flower
Figure 1: Parts of a Flower |
Students need to understand the parts of a flower before they can understand pollination and the problems facing bees. Flowers are made up of many different parts (see figure 1) with distinct functions. The sepal is a green, leaf-like structure that envelopes a bud. Once the flower emerges, the petals are bright, colorful, and designed to attract pollinators. The receptacle is the part of the stem where the flower attaches and is thicker near the joint. The male part is called the stamen and it is composed of a filament, a stem-like appendage to which the anther is connected. The anther holds the pollen. The pistil is the female structure that consists of the stigma, the style, and the ovary. The stigma is the tip of the pistil and is sticky, so pollen will adhere to it. The style is a slim stalk that connects the stigma to the ovary. At the base of the pistil is the ovary, which contains ovules. Seeds form in the ovules upon fertilization. |
Flowers come in many shapes and sizes. As a result the flowers’ structures do not all look the same. Some flowers are incomplete, with only male or female parts, and others are complete, with both male and female parts.
Pollination
Once students understand the parts of a flower, they can explore pollination and how it occurs in flowering plants. Pollination is a process of transferring pollen grains from the anther to the stigma. Pollination is the way that flowering plants reproduce. Flowering plants can self-pollinate or use cross-pollination. Self-pollination occurs only in complete flowers, but cross-pollination can take place in complete or incomplete flowers. Flowering plants that use cross-pollination rely on outside entities to carry out pollination. Various insects, animals, water, and wind are some of the vectors that move pollen grains from one flower to another. Once pollen grains are moved to the sticky stigma of another flower the pollen grain may or may not germinate. If the grain germinates, it forms a pollen tube that descends the style to the ovary. Fertilization occurs when the sperm cell fuses with the egg inside an ovule. Following fertilization, a seed forms inside each ovule.
Why We Need Pollination
As stated in the introduction, about 70 percent of our food comes from animal pollinators. When one considers, “One bite out of every three we take is thanks to pollinators,” it is worrisome, “but every bite isn’t created equal either from a taste point of view or a nutritional one.”3 Upon further examination, 65% of global food production does not rely on animal pollination, as rice, wheat, and corn depend on wind pollination. That leaves 35%, which are dependent on pollinating animals.4 Paige Embry further explains how many of our essential nutrients come from animal-pollinated plants, “Ninety-eight percent of the vitamin C, seventy percent of the vitamin A, fifty-five percent of the folic acid, and seventy-four percent of the lipids come from animal pollinated plants.”5 Realizing this, the disappearing pollinators are cause for much concern. According to Claire Kremen, a scientist as the University of California Berkeley, “If all the pollinators went extinct, we probably wouldn't starve,” Kremen says. “But we'd all have scurvy or some other vitamin-deficiency disorder.”6
Bees Adaptations
Bees and flowers have coevolved over millions of years. They have a mutual relationship where flowers provide food (nectar and pollen) and bees help plants to reproduce by dispersing their pollen. Bees have developed different adaptations, both structural and behavioral, to gather and transport pollen more efficiently. Honey bees and bumblebees have a structure called corbiculae on their legs. The corbiculae act like a pollen basket. Bees wet the pollen with saliva and nectar to form a more compact package.7 These “pollen pellets” are primarily used to feed developing bees. Other species of bees have a structure called scopa. This structure features elongated hairs on the hind legs. Still other bees have Megachilidae, which is essentially scopa on the underside of their abdomen. When bees fly a slightly positive static electric charge builds up that attracts the slightly negatively-charged pollen grains. Bees also use behavioral and structural adaptations within the hive. Bees create bee bread through a fermentation process. Bee bread is made by filling a honey comb cell about three-quarters full with pollen, then adding honey before capping the cell with wax. This process preserves the pollen for the future (see figure 2).
Figure 2: A frame of honey bees with bee bread
A Brief History
Pesticides and Herbicides
Humans have been innovating as long as they have existed. Through the many iterations and “improvements,” the effects seem to be more detrimental to our world. Humans have used pesticides to protect their crops from insects since ancient times. Sumerians and Egyptians used compounds and created pesticides. The Romans invented the first chemical weed killer.8 The use of chemicals has only expanded as the world became more industrialized. In 1880, the first sprayer was invented and in 1921, the first aerial spraying dropped creosote over Ohio.9 In 1935, DDT was invented to fight malaria-carrying mosquitos. DDT had a low toxicity to bees, but when it was banned, it was soon replaced with fenitrothion which was more harmful to bees.10 More recently, neonicotinoids, a systemic insecticide, is the pesticide of choice, which seems to have debilitating effects on bees over multiple generations. These are all human-developed technologies invented with one goal in mind: extermination of a pest. Without the consideration of unexpected uses and consequences of these technologies, we find ourselves on the verge of real ecosystem modifications and extinction.
Beekeeping
Beekeeping has also changed over time. There are about 4,000 native species of bees in the United States and Canada.11 Honey bees are not native to North America and were brought here by the colonists, first in 1622 to Virginia, then in 1639 to Massachusetts.12 Soon honey bees were kept throughout the entire east coast. In the 1800’s, Lorenzo Lorrain Langstroth, a Yale alumnus known as the Father of Beekeeping, invented the movable frame hive that is still used throughout the world today. The Langstroth hive makes it possible to pull out a frame (see figure 3) without destroying the hive, thus eliminating the need for swarming bees. Apiculture, or beekeeping, has evolved over time and like everything else is driven by the almighty dollar.
Figure 3: A movable frame with a nice brood of honey bees
The Ancient Egyptians moved bees up and down the Nile River to pollinate various crops. The first record of renting bees for pollination in the United States was in 1910. The Honeybee Act of 1922 was passed to ban the importation of honeybees to prevent the spread of disease.
Bees
Native Bees (Wild Bees)
Native bees are a keystone species, meaning that they are critical to the food web. The survival of many other species depends on their survival. Of the 4,000 species of bees that are native to the United States and Canada, there are 456 native species in Virginia. None of the native species in North America or Canada are as organized and sophisticated as the honey bee.13 However, native bees should not be overlooked! According to United States Geological Survey, “Native bees are estimated to pollinate 80 percent of the world’s flowering plants.”14 Native bees fly at different times of day and some fly in bad weather. They carry pollen and touch the stigmas of flowers in different ways. Research suggests that small bees pollinate basal stigmas and larger bees pollinate apical stigmas. Pollination is more successful in strawberry flowers when both groups pollinate the flower.15
The book Our Native Bees mentions a large, worldwide study that categorized bees by size, sociality, and nest site. It compared pollination with a variety of species to a variety of types. The study concluded that a variety of types was more important than the variety of species. When the number of types of bees that visited an orchard increased from 1 to 4, the seed set (the number of seeds per pollinated flower) nearly tripled.16 The use of native bees provides a variety of types and enhance pollination. Thus, it is beneficial to attract native bees to farms and orchards.
Bumblebees and other native bees use buzz pollination, a technique where the flower is vibrated to shake the pollen out of the flower. Honey bees do not know how to do it. Tomato, eggplant, blueberry and kiwi plants require buzz pollination. There are roughly 50 species of bumblebees in the United States, and they live in every terrestrial ecosystem in the nation.17 There are 14 species of bumblebees in Virginia.18 Many are in decline and the rust-patched bumblebee, native to Virginia, is considered endangered.
Blue orchard bees (Osmia lignaria or BOBs) are hard-working pollinators, who are not afraid to work in the rain unlike honey bees. Blue orchard bees are a type of mason bee and are more efficient pollinators than honey bees. “Six mason bees can pollinate an entire fruit tree; it would take 360 honey bees to pollinate the same tree.”19 The blue orchard bees are one type of mason bee. They nest in abandoned beetle tunnels, hollow stems, or holes in wood. They are called masons because they use mud to create separate cells in a tunnel for their young. Mason bees carry pollen on their bellies. Mason bees are not aggressive and do not sting!
Honey Bees
Honey bees were brought to North America from Europe. Commercial beekeepers raise honey bees for pollination. Today, honey bees are shipped all over the country on flatbed trucks. Commercial beekeepers follow the crops and the money. In February, they travel to California to pollinate almond trees. In March they move to Washington for the apples and in May they arrive in South Dakota for sunflowers and canola. Then they head east and reach Maine in June for blueberries and Pennsylvania for pumpkins in July. [20 As the number of honey bee hives has been declining and the crops requiring bee pollination have increased, it was necessary to waive The Honeybee Act in 2004 on an emergency basis. With the waiver, bees were flown in from Australia to reinforce the American hives.21
Problems the Bees Face
Politics
The problem facing pollinators is as complicated as it is controversial. Colony Collapse Disorder has ravaged the honey bee population and commercial industry. Researchers and beekeepers have proposed countless explanations, including the debunked claim that cell phone towers played a role in colony collapses. While naturally-occurring factors, such as viruses and insects, can cause harm to bees, man-made phenomena (e.g., pesticides, herbicides, transportation, etc.) can also be deadly to bees. This interference of man-made phenomena may be why the strife of honey bees has become political. Putting differing viewpoints aside, the problem facing pollinators must be addressed. Insects and their roles in the biosphere are intricately tied to food production, agricultural security, and human health. President Barack Obama’s administration created the Pollinator Task Force, which issued the 2015 report National Strategy to Promote the Health of Honey Bees and Other Pollinators. The White House called for $82 million in federal funding to support pollinator health. While there are many possible explanations for the collapse, human impact seems to be an underlying cause for most, if not all, of the problems linked to the collapse of bees.
The Elusive Cause
Honey bees face a mountain of problems: varroa mites, hive beetles, Nosema fungus, wax moths, foulbrood, chalkbrood, stonebrood, Israeli acute paralysis virus (IAPV), deformed wing virus, Colony Collapse Disorder (CCD), poor diet, pesticides, stress and overwork, pesticides, and many more viruses. CCD is the greatest problem and mystery currently facing honeybees. CCD has devastated the honeybee industry. The cause of CCD has been elusive. As beekeepers and scientists try to determine the underlying cause of CCD, a variety of theories have been explored. One idea was that the timing of the CCD plague of 2006 – 2007 seemed to coincide with the waiver of the Honeybee Act and the bees that were imported from Australia and sent to pollinate the almonds in California. It appeared that Varroa mites were the culprit, but upon further investigation mite counts were no different in collapsed hives than in healthy hives. Besides, Varroa mites exist all over the globe except in Australia and Hawaii. Compounding the problem was the stigma of hive collapse, known among apiaries as PPB, or piss poor beekeeping, which caused gross underreporting of collapses. Whatever was going on even repelled the usual hive robbers from wax moth to bear.
In the winter of 2007, 30 billon bees died, and no one knew why.22 Dennis vanEngelsdorp, Pennsylvania’s state apiarist, examined some deadouts, or collapsed hives, and the remaining bees under a microscope. He noticed that the organs showed signs of rare fungal infection last reported about 50 years ago. VanEngelsdorp determined that the whole immune system of the bee had collapsed, similar to AIDS.23
VanEngelsdorp and other bee experts formed a group, the Colony Collapse Disorder Working Group at Penn State. The ideas for the cause vacillated from cell phone radiation to GMO food, to global warming. But, as each theory was closely examined, it was eliminated when evidence was contradictory. As the research went on, new theories emerged: Israeli acute paralysis virus (IAPV), fungus Nosema ceranae, and agricultural collapse disorder, and the impact of bee farming. These too were dismissed.
Evolution of Farming Practices
Prior to World War II, the United States had about 4.5 million beehives. In 2007, there were about 2 million beehives.24 Changes to farming practices after World War II have greatly affected bees. Prior to the war, cover crops were used to improve the nutrients in the soil. After the war, farmers started using synthetic fertilizers followed by herbicides to kill the weeds. Many of the weeds that were killed were flowering plants that were needed for the survival of bees.
Monocultures
Farmers started growing monocultures, or fields of one crop, which over the years have become larger and larger. Farmers used to plant multiple crops to diversify their risk of a catastrophic loss. However, the federal government provides a safety net, which essentially encourages farmers to plant one crop. Monocultures are bad for the bees for several reasons. Monocultures provide a large food supply for a particular insect that feeds on the crop, which attracts the pests in large quantities. Thus pesticide use increases. Monocultures also create food deserts for bees since there is only one crop. The almond crop is a prime example. In 2020, it was estimated that 1.2 million acres in California were used to grow almonds.25 The almond crop requires almost the entire bee population of the United States or about 2.4 million bee colonies, to pollinate it.26 The bees are trucked in from across the country and following the almond bloom are trucked out since the area is flowerless. Since World War II, bees have been dying, yet the production of crops that require bee pollination has increased 300%.27 Monoculture farms have been beneficial to farmers, but detrimental to the bees.
Pesticides
Pesticides are used commercially and residentially to control pests. In 2007, Americans spent $12 billion on pesticides or 850 million pounds! Sixty-six million pounds were used on homes and gardens. About 2/3 was used for agriculture and the rest was used by the government and commercial industry.28
Neonicotinoids is a potent class of pesticides. They are used for crops, turf, ornamentals, and on pets (control fleas). Acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam are the chemicals that are considered neonicotinoids. Farmers coat seeds in neonicotinoids. This class of pesticides is systemic and moves through the entire plant. When an insect takes a bite of a leaf, it gets a lethal dose. If a large amount is applied at the base of a plant, the pesticide can travel through the plant and get in the nectar and pollen. A large dose can cause a bee to twitch and die. The bees also can get a smaller dose when the seeds are coated. With a smaller dose, bees may appear to be intoxicated and disoriented. Bees also carry the pesticide-laden pollen back to the hive where it is used to feed brood (egg, larvae, pupa). The brood only eat in the larvae stage and are fed Royal jelly, which is comprised of pollen and a chemical produced by worker bees.
One theory that is still under consideration is sublethal doses of neonicotinoids, a class of pesticides. What are the long-term systemic effects of small doses over and over? This could be akin to smoking cigarettes every day. Studies from Italy, France, and the UK using an insecticide, imidacloprid, support this premise. The studies show that systemic long-term exposure to neonicotinoids is causing neurological impairments similar to Parkinson’s and Alzheimer disease that cause the honey bees to become disoriented and unable to find their way back to the hive. They die from exposure and seem to disappear. Recently there are reports and class action lawsuits cropping up claiming that Paraquat, an herbicide, is linked to Parkinson’s disease in humans. Honey bees are roughly 700,000 times smaller than the average human, so it is no wonder that these dangerous pesticides and herbicides may be killing massive amounts of honey bees and driving other predators away from the hives.
Human impact, whether from evolving farming practices, beekeeping practices, or loss of habitat, seemingly plays a role in every facet of the crisis. So, it is up to humankind to do what we can to remedy the situation and help the bees.
Possible Ways to Help
Regulation
In January 2020, the EPA came out with an interim decision to provide more guidance on the use of neonicotinoids. The EPA offers management suggestions to keep the pesticides on the intended target and to reduce the use on plants. The guidance also restricts applications when crops are in bloom to protect the bees. Though this will do little to help if the seed has been coated and the pesticide is already within the plant. The guidance suggests language on the packaging label that advises homeowners not to use the product. The last point is that imidacloprid, a widely used insecticide, cannot be sprayed on residential turf due to health concerns. The website also indicates that the EPA will work with the industry to develop management and stewardship practices.29 Clearly neonicotinoids and the health risks to bees, humans, and the environment are on the radar and are beginning to be addressed.
Farming
Farmers use less herbicides and pesticides on their farms and adopt organic farming practices. One farming practice that would help the bees is to plant cover crops. Clover and alfalfa are highly nutritious for bees, but they are also beneficial in other ways. Cover crops reduce run-off, erosion, and the transport of fertilizers and pesticides to waterways. The use of cover crops fixes nitrogen in the soil which increases the natural nutrients and reduces the need for synthetic fertilizers. Cover crops also suppress weeds and may decrease the use of herbicides. Gabe Brown, a farmer in North Dakota, uses four different types of cover plants for the purpose of having live roots in the soil all year round. “Even a modest two or three species cover crop causes a 90 percent reduction in sediment runoff and a 50 percent reduction in fertilizer runoff into the watershed and sequesters a metric ton of carbon dioxide per acre.”30 In addition to helping the bees, cover crops provide other benefits for our environment.
Native Plants
Planting native plants is one of the most important ways to improve pollinator health. Native plants and animals have co-evolved. Therefore, native species of plants work well together and support one another. Native plants are not only important for pollinators, but for the entire ecosystem. Native plants invite plant-eating insects as well as their predators, and other organisms that fill niches in an ecosystem. Dr. Doug Tallamy, author of Bringing Nature Home sums up how native wildlife prefers native plants. He explains how a native oak supports 532 species of native caterpillars and a non-native Butterfly Bush only supports one species. Planting native plants will not only impact the bees, but also help the entire ecosystem!
Nesting Places
Native pollinators are attracted to native plants, but they also need a nesting place within their flying range (See Figure 4). Depending on the type of bee, the range can vary from a few hundred feet to a couple of miles. Bare patches of dirt, holes in wood, cracks in stone and concrete, and hollow stems are potential nesting sites. Some bees are ground nesters and others are cavity nesters. Honey bees are the only bees that build hives. It is helpful to the bees if some natural materials are in the yard.
Figure 4: Where do native bees nest? Credit: Gary Bentrup, USDA National Agroforestry Center
Avoid Pesticides
People should avoid pesticides whenever possible. If they cannot be avoided, then people should do their best to choose a pesticide that is less harmful to the environment. The neonicotinoids are more potent and should not be used. Another solution to chemical pesticides is to purchase natural predators such as lady bugs or inspect and remove pests by hand.
Clover
Clover not only provides benefits as a cover crop, but also when it intermingles in lawns. When clover grows among grass, the grass is lusher and greener. This is because clover houses a bacteria in its roots that removes nitrogen from the air and turns it into a form that can be used by plants. A nitrogen-fixing legume, like clover, can provide most of the nitrogen grass needs if it occupies about 30% of the grassy area.31 In addition to its nitrogen-fixing capabilities, clover also provides a food source for pollinators. Maybe a public relations campaign is needed so clover is recognized as a pollinator plant and not as a weed.
Design Thinking
The design process is a structure for problem solving and testing. The goal is to develop a solution that solves a societal problem, which may have multiple solutions. The Science and Engineering Practice in the Virginia Standards of Learning uses a model based on the National Aeronautics and Space Administration (NASA) engineering design model. There are eight steps which are: 1) Define (the problem), 2) Imagine (brainstorm a solution), 3) Research (research the problem and possible solutions), 4) Plan (a device to address the problem), 5) Build (a device to address the problem), 6) Test (to see if the device works), 7) Improve (the device), 8) Share (communicate results to stakeholders and public).
In the Human-Centered Design of Biotechnology seminar, Anjelica Gonzalez shared a five-step iterative process (See Figure 5). Both models are similar and both processes define the problem.
Figure 5: Design Thinking Iterative Steps by Stanford d.school and the updated 8 design abilities
In seminar, the use of a problem statement such as, “How might we help _____ to ______?” is recommended to clearly define the problem. The design thinking model uses Empathize instead of Research step. This is an important distinction as the work of the seminar is focused on human-centered design which takes into consideration the need and the context.
An example from seminar is when incubators for premature babies were brought to Malawi. Upon a subsequent visit the incubators were in a medical equipment graveyard. This was because the incubators broke, the parts were expensive, and people did not know how to fix them. The context of Malawi was not addressed. When the context was considered, the incubators were redesigned and made from car parts that were readily available, and the local mechanics were able to repair the newly designed incubators.
The design thinking process focuses more on interviewing as a method of research. The Imagine step is essentially the same as the Ideate step. The Plan and Build steps in the Virginia Standards are combined into one step, Prototype, in the design thinking model. Both models have Test as a step. The design thinking model fuses Test and Improve into one step. No matter which “steps” are followed, this is where the iterative process of test and improve are repeated until improvement is attained. The last step in the process in the Virginia Standards is Share. There is not a comparable step in the 5-step process, but the product would be shared, otherwise there is no sense in going through the process. The steps elucidated in Anjelica’s seminar are more concise and human-centered, but they are quite comparable.
Computer programming
Four decades ago, Seymour Papert, the Father of the Maker Movement, asked, “Why were computers being used by schools in such unimaginative ways?”32 He also advocated for children to make things using computer programming. Papert and Cynthia Solomon, the co-creator of the Logo coding language, envisioned a school computer with many ports that would control lights, motors, and sensing devices.33 Scratch is a version of Logo. Unfortunately, many schools continue to use computers in such unimaginative ways. A few years ago, I attended a session at a math/science conference about coding. I knew almost nothing about coding at the time. The session sparked my interest and connected me to other educators who were using Scratch, Makey Makey invention kits, and Hummingbird robotics kits. Since attending the conference, I attend regular Scratch Meetup sessions and have been learning and implementing these technologies into my classroom. The students love it!
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