Posted by: Lisa Mason, Arapahoe County Extension
Last week was National Pollinator Week!
We should celebrate pollinators every week because they provide so many
benefits to humans and ecosystems! Many people are well aware that bees are
declining all over the world for a variety of reasons including habitat loss,
pesticide use, parasites, diseases, climate change, etc.
Pollinators include bees, bats, flies, beetles, wasps, ants,
butterflies, moths and some small mammals. Bees are among the most efficient
pollinators because the pollen sticks to the hairs on the bee.
 |
| Two-tailed swallowtail, Papilio multicaudata. Photo: Lisa Mason |
Why should we care about pollinators?
Pollinators provide valuable ecosystems services. They
transfer pollen grains from one flower to another which enables the plants to
reproduce. Here is a closer look at the value pollinators have to humans and
ecosystems.
- 75% of more than 240,000 plant species rely on pollinators for reproduction.
- The global production of crops that depend on pollinators is an industry worth up to US $577 billion annually.
- Bees help to pollinate 1/3rd of the human diet including the most nutritious part of our diet—fruits, vegetables and nuts.
- In addition to crops, they pollinate the food for livestock that contributes to the meat and dairy industry.
Our planet has an incredible amount of bee diversity! Most of
us are familiar with the honey bee (Apis
mellifera), a non-native bee species to the United States. The honey bee
was brought over from Europe in the 1600’s. In addition to the honey bee, we
have approximately 20,000 species of bees worldwide. We have over 900 species
in Colorado!
 |
| A green metallic sweat bee, Agapostemon sp. Photo: Lisa Mason |
 |
| A leafcutter bee, Megachile sp. Photo: Lisa Mason |
Where you can you find the bees?
Bees come in all sizes, shapes and colors. Take a close look
at the flowers in your garden this summer. You are likely to see bees buzzing
around in pollinator-friendly plants! To get an idea of the bees that are in
your garden, check out the Native
Bee Watch Citizen Science Field Guide.
When the bees aren’t foraging in flowers, the females are
likely at their nesting site. Of all the bees in the world, approximately 90%
are solitary bees which means they mostly do not interact with other bees with
the exception of mating. Of those bees, about
70% live underground and the other 30% are cavity nesters. Solitary bees have a
one-year lifecycle.
Some bees are generalists or polylectic, meaning they
collect pollen and nectar from a variety of flower species. These bees are
opportunistic but still may prefer certain flowers. A specialist or monolectic
bee only feeds on a specific plant species. Monolectic bees have generally
coevolved with a specific plant species meaning the plant and bee depend on
each other for survival.
A squash bee, Peponapis pruinosa. Photo: Lisa Mason
Do you enjoy pumpkins
and squash?
If so, thank a squash bee! They are a great example of a
specialist bee. In Colorado, we have one species, Peponapis pruinosa. Squash and pumpkin plants need these bees to
pollinate the flowers so they can reproduce. They have special pollen
collecting hairs on their hind legs that helps to transport the pollen. One
research study showed that not only were squash bees more efficient at pollinating
squash plants, but they pollinate earlier in the morning when pollen and nectar
is readily available. By the time honey bees start foraging, the squash bees
have already pollinated the flowers. If you look in the early mornings at the
big yellow flowers on your squash or pumpkin plants, you are likely to see
squash bees in the flowers.
Squash bees and other native bees need your help! By
developing habitat in your yard, you can provide food, shelter, water and space
for native bees and other pollinators. Check
out this blog post on creating pollinator habitat. You can also check out
the following fact sheets:
Have fun observing bees in your garden!
 |
| A cactus bee, Lithurgopsis apicalis. Photo: Lisa Mason |
References:
- The Pollinator Partnership
- The Bees of Colorado
- Native Bee Watch Citizen Science Field Guide
- The Forgotten Pollinators
- The Food and Agriculture Organization of the United Nations
- The Pollination Efficiency of the Squash Bee (Peponapis pruinosa) and the Honey Bee (Apis mellifera) on Summer Squash (Cucurbita pepo)
