What are wild pollinators?
The “pollinator crisis” has received a lot of media attention over the past decade, and most people are aware that "pollinators" are in trouble. Much of this attention has focused on the collapse of non-native, managed honey bee populations due to their tremendous economic importance as crop pollinators for human agriculture.
However, the sharp decline of many of our native pollinator species, though less recognized, is an ecological crisis of similar magnitude that also deserves our attention. These insects, birds, and mammals provide vital ecological services that are imperative for the proper functioning and resilience of our local ecosystems, especially in the face of climate change. By not recognizing the role our actions play in their decline, we ignore the need to protect these diverse and critical species.
Why are Pollinators in Crisis?
Many pollinators around the world, including in Massachusetts, are in crisis. Although the exact mechanisms causing their decline are not fully understood, several factors are thought to play major roles. The good news is that we can mitigate many of these things, especially in our private yards through responsible land stewardship practices, that will have immediate, positive impact.
Milder winters and hotter summers directly impact the survival of both pollinators and native plants. Pollinator systems have co-evolved so that pollinators and the native plants they depend on for food and shelter have become desynchronized, impacting native pollinators and the pollination success of native plants.
Habitat loss contributes to pollinator decline through fragmentation of available nesting sites and food sources. As native vegetation is replaced by roadways, manicured lawns (“green deserts”), crops, and gardens containing ornamental plants, pollinators lose the connectivity of resources that ensure their survival.
Although initially thought to be a “safe” insecticide that only targeted “pests”, recent research suggests that neonicitinoids, or “neonics”, (a class of insecticides that are widely used) may be harmful not only to native insects, including pollinators, but adversely affect human health, as well.
Weakened by pesticide exposure, reduced nutrition, and loss of habitat, pollinators have become more susceptible to new pests and diseases, including those introduced from foreign managed honeybee colonies imported for crop pollination services.
Introduced plant species can destroy delicate ecosystem balances by outcompeting native plants, reducing the diversity, and eliminating food and shelter that native pollinators require for survival. Likewise, invasive insect species can compete with native pollinators for limited resources.
Why Does This Matter?
Massachusetts is home to thousands of native pollinator insect species. Many species are declining or have become extinct, although some have increased in abundance. In Massachusetts alone, 3 of the 9 remaining bumblebee species are at risk of extinction within the next decade.
Wild pollinating species, primarily insects, represent a vast functional diversity. The majority of these animals are "generalists," meaning they depend on a variety of different plant types for pollen and nectar. However, many pollinators are "specialists" relying on a single plant species (or a small number of highly-related plants) for survival.
Meet the Pollinators
What about honey bees?
Although one of the most recognizable pollinators, honey bees are a single introduced species, brought to America by European settlers to provide honey and beeswax
The contributions and challenges of managed honeybees are well documented in an agricultural context
Honey bees are highly social and, unlike native bees, can be very aggressive when protecting their hives
Photo credits: Native bee- Nicole Mordecai; Fly- Sarah Maas Scheuplein; Butterfly- Nicole Mordecai; Moth- Victoria Huber; Beetle- Rbreidbrown, CC BY-SA 4.0, via Wikimedia Commons
Bumblebees, the most recognizable native bee species, are social and live in small hives underground
Bees are extremely efficient pollinators
Other types of native bees include carpenter, sweat, mason, digger, miner, leafcutter
Most native bees (~90%) are solitary and nest in cavities or in the ground
~75% of native bees are generalists, meaning that they visit many types of flowers
Different bees have different tongue lengths (long, medium, or short), so prefer different types and shapes of flowers depending on their anatomy
Incorporating a wide variety of flower shapes, colors, and sizes will attract many different native bee species
Thought to be among the most ancient pollinators, beetles have been pollinating certain plants including magnolias, spicebushes, and water lilies for ~200 million years
Beetles appear to prefer more open flowers with strong, fruity, or rotten scents, usually white or green in color
The Ruby-throated Hummingbird is the only bird pollinator in the eastern US
Ruby-throated hummingbirds overwinter in Central Mexico and return to breeding grounds in the eastern US and Canada every spring
Hummingbirds are drawn to red tubular shaped flowers that match the shape of their bill (for example, Cardinal Flower, Wild Red Columbine, and Trumpet Vine)
Wasps are mostly "incidental" pollinators, passively carrying pollen from flower to flower as they nectar instead of actively collecting it, like bees. They have less body hairs so are less efficient at pollination since the pollen doesn't stick to them well
Wasps are beneficial insects, performing essential ecosystem services like managing pest insect populations through predation
Social wasps can be aggressive when threatened, but solitary wasps (the large majority of wasp species) rarely sting and should be left in place when possible
Butterflies are some of the showiest garden visitors and rely mostly on nectar-producing flowers
Some butterfly species remain local throughout their entire lifecycle, while many other species migrate, returning to northern breeding grounds in spring or summer
The most famous migratory butterfly species, the Monarch, has declined by more than 80% in the past 20 years
Butterflies prefer brightly colored, open flowers such as Joe-Pye weeds, goldenrod, and milkweed (also the host plant for Monarchs)
Although there are no flowers that rely on bats for pollination in Massachusetts, bats are necessary for pollination of certain flowers such as many fruits, agave, and cacti in the Southwestern U.S.
Much like moths, bats also rely on flowers that are open at night, and color is not as important
Flies are a diverse group of insects and are important pollinators
Flies are often generalists, pollinating many different flower species
Some fly species resemble bees or wasps but only have one pair of wings instead of two
Larvae of many hoverflies are beneficial and prey on aphids
Flies seem to prefer dark brown or purple flowers that smell like rotting flesh (e.g. skunk cabbage)
Closely related to butterflies but mostly active at night (notable exception is the hummingbird moth, shown above)
There are many more native moth species than butterflies
Moths visit many of the same flowers as butterflies, although flower color is less important and flowers need to be open at night