the importance of pollinators
When we think of pollinators and pollinator decline, we generally think of honeybees. The plight of the honeybee due to Colony Collapse Disorder (CCD) and the impact that has on our agricultural industry has been well documented and rightly so. Nearly one in every three bites of food is directly or indirectly pollinated by honeybees - almost $15 billion worth of US crops annually. As new beekeepers ourselves here at Sparrow Gardens we are on the front lines when it comes to managing the many threats honeybees face, and we work hard to keep our hives alive and thriving in spite of the manmade and natural hazards which are working against them. The three main reasons for global honeybee decline are industrial agricultural practices, parasites and pathogens, and climate change. Within these three causes industrial agriculture has had the greatest impact due to its destruction of habitat, loss of biodiversity, and use of herbicides and pesticides. During the 2017/18 winter beekeepers in Massachusetts lost nearly 60% of their hives (https://bip2.beeinformed.org/loss-map/). This level of hive loss is unsustainable and scientists are scrambling to figure out how to head off a crisis in our food security if honeybees continue to face such heavy losses.
A second pollinator we may also be familiar with is the Monarch butterfly. The decline of the Monarch due to loss of habitat - specifically the eradication of milkweed, their host plant, and the loss of their overwintering sites in California and Mexico, along with higher spring and summer temperatures forcing them further north - has also been in the news. The US Fish and Wildlife service (https://www.fws.gov/savethemonarch/ssa.html) was petitioned in 2014 to add the Monarch to its Endangered Species list. This listing is currently under review and a final finding is due in June of this year, however, the Western Monarch Thanksgiving Count of 2018 found that the number of Western monarchs overwintering in California had dropped by 86% and the number of Eastern monarchs wintering in Mexico had dropped 15%. Both of these drops were just from the prior year, over the past 20 years the numbers have dropped more than 80 percent. And this drop is occurring despite the extensive press coverage regarding monarchs, milkweed, and the importance of pollinators.
Both the honeybee and the monarch butterfly are what’s called “indicator species” in that they are the most visible of the pollinators and therefore act as the proverbial “canary in the coal mine” for the rest of the pollinators which do not garner such extensive coverage. It is these unsung pollinators, however, that we should be most concerned about. They are also in rapid decline and are responsible for the majority of the pollination which occurs in the wild. They include over 4,000 species of native bees (honeybees are not native to our region, they were imported from Europe in 1622), butterflies, moths, beetles, flies, birds, and bats. These native pollinators are part of an intricate web which supports the biological diversity of the natural world around us and consequently sustains our quality of life.
Within the native bees, bumblebees are especially important pollinators due to their size and ability to transfer large amounts of pollen. The rusty patched bumblebee, Bombus affinis, is on the US Fish and Wildlife Service’s endangered species list - the first bee in the U.S. to be given such protection. Many pollinators develop a mutually beneficial relationship with the plants they pollinate, with the plant providing the nectar and pollen and the insect or animal adapting its physical characteristics or behavior to access the pollen from that particular plant. The bumblebee and the tomato have such a relationship, with the bumblebee practicing buzz pollination - biting and shaking the pollen from the flower - enabled by its size and extra fuzzy body to capture the loosened pollen. Here on the Cape we have the Common Eastern bumblebee (Bombus impatiens), the Confusing Bumblebee (Bombus perplexus), and the Brown-Belted Bumblebee (Bombus griseocollis). Other important native bees include sweat bees, leafcutter bees, and mason bees.
There are 110 species of butterfly in Massachusetts, with 71 residing on Cape Cod. Of the 110, seven are currently listed on the Endangered Species list: Mustard White, Bog Elfin, Frosted Elfin, Hessel’s Hairstreak, Early Hairstreak, Persius Duskywing, and Dion Skipper. Though their numbers are low compared with bees, they are important pollinators nonetheless. Familiar species are the Viceroy, Painted Lady, American Copper, Mourning Cloak, Black Swallowtail, and Baltimore Checkerspot. Butterflies prefer a sunny spot sheltered from the wind, with some open areas for basking and wet areas to gather moisture and soil minerals. A wildflower meadow is the ideal butterfly habitat, and should be maintained by mowing once per year in the late fall to a height of six inches. Host and favored plants of butterflies include milkweed, joe-pye weed, blueberry, aster, monarda, sedum, willow, poplar, aspen, thistle, goldenrod, lavender, and the evergreen violet.
Moths and Bats
After dark moths and bats take over pollination in the natural world. Nocturnal flowers that are pale or white (think moonflower) with heavy scents and a large amount of nectar attract these pollinators. Not all moths are nocturnal however, and species such as the Hummingbird Hawk moth, the Clearwing moth and the Sphinx moth can be seen hovering above liatris or camassia during the day. Decline in moth counts can be attributed to habitat destruction, overgrazing by deer, climate change, light proliferation, elevated bat predation by night and bird predation by day. The last two causes highlight the importance of moths and their caterpillars as an important food source for a wide variety of wildlife including frogs, lizards, spiders and other insects, in addition to bats and birds. Their loss affects the entire food chain, all the way up to us.
Beetles were one of the first insects to visit flowers, and they remain important pollinators today. In fact they are the largest group of pollinating animals due to their extraordinary variety (over 30,000 species), responsible for pollinating 88% of the flowering plants around the world. They are especially important for ancient species such as magnolias and spicebush. There is no definitive data on beetle decline as targeted studies have not been done, but all evidence points to a similar decline as with other insect pollinators. Beetles are essential food for many birds, reptiles, amphibians and fish and without them these animals will starve.
True flies (order Diptera) may have been the first pollinators, with fossil records dating back to 250 million years ago. They are also the most varied of the insects, with over 150,000 known species. Flies tend to pollinate plants that grow in cool, moist, shaded areas, and their value as a pollinator is second only to the honeybee as far as agricultural crops are considered. In fact, cacao (from which chocolate is made) is pollinated exclusively by flies (tropical midges). Though flies cannot be “kept” like honeybees, they can be used to pollinate crops in greenhouse environments. There have not been any significant studies for the population trends of flies in North America, so whether or not they are in decline cannot be definitely stated. That said, one North American species, the Delhi Sands fly (Rhaphiomidas terminates abdominals) has been placed on the U.S. Endangered Species list.
When we think of pollination by birds we tend to think of hummingbirds, and they are the major contributor in this category. There are 18 species in the United States, 9 in Canada, and 63 in Mexico. With their habit of migrating for the winter months, they have become important pollinators for wildflowers in most of North America. In fact, many species of flower have adapted over time in order to attract hummingbirds. The most popular forms are flowers which are tubular, brightly colored, and relatively odorless - think foxglove, pulmonaria, trumpet vine, and honeysuckle.
In addition to hummingbirds, several other species of bird aid in a minor way in pollinating wildflowers and trees, including white-winged doves (cacti), orioles, wrens, jays, blackbirds, and others.
What can be done?
While the problem of pollinator decline is a daunting one, there are things you can do as an individual to help and collectively these small actions add up. You can plant native flowers in your gardens, create a meadow to provide shelter for insects, use fewer pesticides on your lawn and around your home, and create a water source - small pond, birdbath, etc. - for insects to use. Ultimately it will be policy changes in Washington and around the world that will make the greatest impact. The EU and the UK have made tremendous strides in banning pesticides that have been determined to harm pollinators. While we are not as progressive here in the United States, in 2016 the Obama administration did introduce and pass the “Pollinator Partnership Action Plan” to aid honeybees and monarch butterflies. Its goal was to “restore or enhance 7 million acres of land for pollinators over the next 5 years.” These are the types of policies which can make a huge difference, and as citizens we can urge our representatives to introduce and pass similar measures during their time in office. Change is up to us, in big and small ways we can make a difference.
The Pollinator Partnership (https://www.pollinator.org)
Learn about and purchase native plants on the Native Plant Trust website (http://www.nativeplanttrust.org)
Visit native plant sanctuaries (http://www.nativeplanttrust.org/visit/native-plant-sanctuaries/)
Listen to the NPR program “The Impact of a Global Decline in Pollinators” from April 4, 2019 (https://www.capeandislands.org/post/impact-global-decline-pollinators#stream/0)
Bee and Pollinator Books by Heather Holm (https://www.pollinatorsnativeplants.com)
Native Plants and Native Bee downloadable posters (https://www.pollinatorsnativeplants.com/plant-lists--posters.html)
Monarch citizen scientist page: (https://monarchjointventure.org/get-involved/study-monarchs-citizen-science-opportunities)