Plant of the Week: Douglas Aster (Revisited)

Image from: http://www.nwplants.com/

This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University.  It highlights one of the plants that Aaron Anderson is using in his research.

Original “Plant of the Week: Douglas Aster” post available here: http://blogs.oregonstate.edu/gardenecologylab/2017/11/07/plant-week-doulgas-aster/ 

Last November I took a look at a Pacific Northwest favorite, the Douglas aster (Symphyotrichum subspicatum (1)). What I didn’t know then was just how popular this species would be with the bees we had been sampling in the field. It turns out that while surveyed gardeners ranked Douglas aster 14 out of 27 in terms of attractiveness, based on the 2017 data it boasted the third highest number of bees (2). This means that it is the most attractive native perennial species for bees that we sampled, and the 2018 data shows this as well (3). Based on the gardeners’ ranking, however, which placed it in the bottom 50% of all the species we sampled, it also looks as though the Douglas aster is in need of some public relations help. 

It is my personal belief that it isn’t just the showiness of the blooms or the potential benefits to X, Y and Z that brings plants into our gardens, but rather the stories we tell about them. Familiarity after all is more than just recognition; it is also marked by appreciation and understanding. One of the stories we can tell through our work in the Garden Ecology Lab about Douglas aster is of its relationship with our native bees. As gardeners we are uniquely positioned to both benefit from and to be of service to these insects. 

Here are some of their “faces”: 

Long-horned Bees

Melissodes sp. 

The most common genus of bees collected from Douglas aster in the field, Melissodes are true summer and fall flyers, easily recognizable by their long antennae. These bees are solitary ground nesters, although they have been observed forming nesting aggregations in the soil (4). While we collected potentially five species of Melissodes in total, one species in particular, Melissodes microsticta, was especially common. Many Melissodes species are generalists, but can usually be found visiting members of the Asteraceae family (such as sunflowers and our Doulgas aster) because of their late season blooms.

Image from: https://odabeeguide.weebly.com/melissodes.html

Yellow-faced Bumblebee

Bombus vosnesenskii

The second most commonly collected visitor of Douglas aster, the yellow-faced bumblebee is really a remarkable native pollinator. While many native bees are considered solitary, bumble bees are social insects, with a queen and workers (4). Like non-native honeybees, they have been investigated for their potential as commercial pollinators, being used in greenhouse production (5). Isabella Messer wrote a post for the “Pollinator of the Week” series highlighting these ubiquitous bees that can be found here: http://blogs.oregonstate.edu/gardenecologylab/2017/08/29/pollinator-week-yellow-faced-bumble-bee/ 

Image from: https://odabeeguide.weebly.com/bombus-sp.html

Ligated Furrow Bee

Halictus ligatus

The third most commonly collected visitor of Douglas aster is the ligated furrow bee. Found throughout North America, Halictus ligatus is special amongst native pollinators (like the yellow-faced bumblebee) for its social nature (4). Sociality is rare amongst native bees, as it is in nature in general, but amongst the Halictus the situation is even more unique. This is because, unlike other social species, Halictus have been seen to switch back and forth between solitary and social behaviors over time as environmental conditions differ (4). Isabella wrote a post about these bees a while back for the “Pollinator of the Week” series that can be read here: http://blogs.oregonstate.edu/gardenecologylab/2018/04/30/pollinator-week-mining-bee/ 

Image from: https://odabeeguide.weebly.com/halictus.html

Virescent Green Metallic Bee

Agapostemon virescens

The fourth most commonly collected visitor of the Douglas aster is none other than my personal favorite, the virescent green metallic bee. These stunning bees are communal soil nesters and are members of the Halictidae family, cousins of the ligated furrow bee introduced above (4). I wrote a post about them for the “Pollinator of the Week” series last November that can be found here: http://blogs.oregonstate.edu/gardenecologylab/2017/11/13/pollinator-week-virescent-green-metallic-bee/ 

Image from: https://odabeeguide.weebly.com/agapostemon.html

In addition to these bees, we also collected striped-sweat bees (Agapostemon texanus/angelicus), brown-winged furrow bees (Halictus farinosus), metallic sweat bees (Lasioglossum sp.), and common little leaf-cutter bees (Megachile brevis). We also collected with a number of long-horned bees (Melissodes) that have yet to be identified to species. 

Walking the streets of Portland and seeing Douglas aster’s purple flowers still in bloom this late in October brings a smile to my face because it tells me that people are indeed planting this species. If only for its benefit to wildlife and pollinators in particular, that is still good news. As you may be able to tell from the information given above, we are still learning about these bee species while we are simultaneously working to save them — not just for future generations but for ourselves as well. Hopefully, by putting a “face” to the bees that visit and depend on these plants and our gardens, the bond that links us to them can be strengthened and our preference for them in our landscape enhanced. 

Sources: 

1. Geraldine A. Allen 2012, Symphyotrichum subspicatum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=88843, accessed on October 30, 2018.
2. Langellotto, G. (2018, September 12). Do Gardeners Like the Same Flowers as Bees? [Blog post]. Retrieved from http://blogs.oregonstate.edu/gardenecologylab/2018/09/12/do-gardeners-like-the-same-flowers-as-bees/ 
3. Anderson, A. (n.d.). First Look: Research Into Native Plants in the PNW Garden. Webinar. Retrieved from http://blogs.oregonstate.edu/gardenecologylab/2018/10/23/webinar-on-willamette-valley-native-plants-and-pollinators/ 
4. Wilson, J. S., & Messinger Carril, O. (2016). The Bees In Your Backyard. Princeton, NJ: Princeton University Press.
5. Dogterom, M. H., Matteoni, J. A., & Plowright, R. C. (1998). Pollination of Greenhouse Tomatoes by the North American Bombus vosnesenskii. Journal of Economic Entomology, 91(1), 71-75. doi:https://doi.org/10.1093/jee/91.1.71
6. Oregon Department of Agriculture: Bee Pollinators of Oregon. (2016). Retrieved October 30, 2018, from https://odabeeguide.weebly.com