Can Insects Adapt to Non-Native Plants?

 

This is a question often posed to native plant enthusiasts: is it possible that over time Lepidoptera (butterflies and moths) will come to use imported plants as their host plants? It’s a hopeful question for gardeners who like non-native plants, but it’s also a question that scientists are interested in answering in case native host plants decline or disappear.

It’s the subject of a paper just recently published [Specialist Herbivore Performance on Introduced Plants During Native Host Decline] that examined ash (Fraxinus) relatives in the olive family (Oleaceae) that are already here as ornamentals: privet (Ligustrum), Forsythia, and lilac (Syringa). With the decline of ash species due to the emerald ash borer (EAB), it’s a very real possibility that moths and butterflies that use it as a host plant may need to find an alternative host. There is some usage of these plants already by specific insects. The question the paper posed to answer was how productive of a host plant could they be (would the larvae survive to adulthood on these plants or would the plants be ecological traps?).  

Green ash (Fraxinus pennsylvanica)

I appreciate that such research is available to the public. Also included are all of their references, of course, and those are interesting as well. I had no idea, for example, that 5 species of Lepidoptera are considered extinct because of the dramatic decline in American chestnut trees (Castanea dentata) (reference: Wagner, D. L., and R. G. van Driesche.2010. Threats posed to rare or endangered insects by invasions of nonnative species. Annu. Rev. Entomol. 55: 547–568.) Certainly that makes sense and it could foretell the fate of some ash-dependent insects.

The results of this study were mixed. Yes, the studied moths did lay eggs on the non-native plants to some degree Yes, some insects did develop into caterpillars and lived to pupate (form a cocoon). A quote from the paper:

“We found the nonnative host plants provided varied support for larval survival to pupation, with biomass and growth rate affected differently by both plant and insect identity. Nearly all caterpillars reared on one alternative host, European privet, exhibited distinct malformations of the wing buds at pupation. Given caterpillar presence on privet in the field, privet may constitute an ecological trap (i.e., when female moths select a sub-optimal host, offspring survival and fitness are reduced).”

The article is a fascinating read and it contains many interesting references to other studies (like the note about chestnut-dependent insects) as well as mentioning that they were able to use some iNaturalist observations in their research (go, citizen scientists!).

What can we do about EAB? Learn to recognize the emerald ash borer and signs of affected trees so that you can recognize if you have it (and report it to iNaturalist). It is in Georgia. Look for D-shaped beetle exit holes in ash trees and wilting foliage. Don't move firewood as that can contribute to the spread.

Photo: https://www.newhopemn.gov/city_hall/public_works/forestry/emerald_ash_borer

If you want to take a chance on native members of the olive family, plant ash tree species native to your area. In Georgia, that is primarily green ash (Fraxinus pennsylvanica) and white ash (Fraxinus americana). Other members include fringetree (Chionanthus virginicus) and American olive (Cartrema americana).

Native Edible Plants in Georgia

 

Chickasaw plum fruit (Prunus angustifolia)

The interest in growing native plants and growing edible plants has a happy intersection point when you can grow both at the same time. I think the poster plant for this movement is blueberry (Vaccinium), a sun-loving native shrub that is widely cultivated for its fruit. With an open, sunny area that gets 5-6 hours of sun and has room for two bushes, almost anyone can grow this delicious fruit.

Blueberry fruit in my yard

I’ve written several blog posts about native edibles but they were not comprehensive. Someone suggested a straight list of plants to consider so here goes:

Fruits

• Blueberries (Vaccinium sp.) – full sun shrub, need two or more that are not identical. Read more here.
• Huckleberries (Gaylussacia) – part sun shrub, better fruit set with two or more.
• Raspberries and blackberries (Rubus) – full sun prickly shrub that suckers, better fruit set with two or more. Watch out for non-native species.
• Strawberry (Fragaria virginiana) – groundcover plant in full sun to part shade.
• Elderberry (Sambucus canadensis) – full sun large shrub that prefers good moisture.
• Plums (Prunus) – full to part sun large shrub or small tree.
• Paw Paw (Asimina triloba) – part sun tree that suckers, need two more that are not identical.
• Hawthorn, especially mayhaw (Crataegus aestivalis) – full to part sun tree.
• Serviceberry (Amelanchier) – full sun tree.
• Persimmon (Diospyros virginiana) – part sun tree.
• Crabapple (Malus angustifolia) – full sun tree.
• Red mulberry (Morus rubra) – full to part sun tree.
• Grapes (Vitis sp. and Muscadinia rotundifolia) – vines that may need to be managed to stay compact or on specific structures.
• Viburnum – native shrub species in full or part shade, research carefully which ones are best.
• Beautyberry (Callicarpa americana) – full sun shrub with fruits that can be used for jams/jellies.
• Black chokeberry (Aronia melanocarpa) – large full to part sun shrub with edible fruits.
• Prickly pear cactus (Opuntia humifusa) – prickly perennial with edible fruits.

 

Prickly pear cactus (Opuntia humifusa)

Nuts

• Hickory (Carya spp. except for bitternut  hickory) – large trees with sweet nuts.
• Pecan (Carya illinoinensis) – large tree with sweet nuts.
• Oaks (Quercus) – large trees with nuts that can be used for flour and other products. More ideas here.
• Walnut and butternut (Juglans) – large trees with edible nuts.
• American hazelnut (Corylus americana) – small tree or large suckering shrub.
• Chestnut (Castanea) – native trees that can produce nuts when not affected by blight.

 

American hazelnut (Corylus americana)

Herbs

• Beebalm and wild bergamot (Monarda) – full sun and part shade herbs with aromatic foliage for herbal tea.
• Onion (Allium canadense and cernuum) – herb used like chives (bulb is not large)
• Mountain mint (Pycnanthemum) – full sun herb with aromatic foliage.
• Violet (Viola sororia) – wildflower with edible flowers.

 

Common violet (Viola sororia)

Assorted edible roots/tubers 

• Groundnut (Apios americana)
• Sunchoke (Helianthus tuberosus)
• Wild sweet potato (Ipomoea pandurata)

Groundnut (Apios americana)

This is by no means a comprehensive list but rather a collection of some of the most common native plants when it comes to human consumption. Be sure to leave some food for the animals! 

Here are a few useful links that I came across while researching this post:

Edible Plants in North Georgia

Stalking the South's Wild Edibles

What to Forage for Food in Georgia

February 2023 Moment in Nature

It's been a busy few months for us and I'm glad it's been winter so that I could focus on my inside tasks. One of them has been moving a parent into assisted living and preparing to sell their home. This week was the last of the furniture leaving the house, and while I was there I spotted this blooming Carolina jessamine (Gelsemium sempervirens) on an arbor that they built about 20 years ago.

As we leave our residences to move onto the next stage of our lives, some of what we did often remains behind. I hope this cheerful (and early blooming) native vine will persist for the next owner. When it comes to plants, let's leave a legacy of some native plants in our landscapes to inspire the next caretakers.

For now, these blooms are a memory of a chapter closing in our lives; this #momentinnature encourages us to take the time to remember it.

Site-Specific Native Plant Ideas

 

The plant shopping season is coming up. While anyone can buy plants at regular big box stores and nurseries, it is during spring (and fall) when numerous seasonal sales happen and small native plant nurseries bust out with fresh plants so the selection is even better (shop small when you can!). 

Sure, we can go out and load up on plants willy-nilly ("Oh, that looks good!"), but many folks have specific plant needs: something for shade, something for privacy, something for that wet spot. It's important to choose plants that will really thrive in those conditions and accomplish the goal. It’s a concept that is often referred to as ‘right plant, right place.’

Here are some of my previous blogs that address specific needs either because of the conditions or because of what you need it to do.

Shady areas are those that get less than 6 hours of sun per day. In my Made in the Shade blog, I talk about how to identify different levels of shade, and I provide ideas for shade perennials, shrubs, and small trees.

For those occasionally soggy spots, consider plants featured in this post: Rain gardens, wet spots and the native plants that love ‘em. Here you’ll find suggestions for perennials (sun and shade), shrubs, and trees that can live with wet feet or occasional standing water.

Perhaps you need something evergreen for privacy or perhaps to provide cover for birds. One of my earliest posts was about Evergreens and it features evergreen trees and shrubs because lots of people want them. I have lists for both sun and shade.

Perhaps you’re interested in adding something unusual to your garden. Take a look at my two posts on Underused Native Shrubs and Underused Native Trees.

My blog post about Native Fruits in Georgia is one of my most popular. Look at it for ideas to add some native edibles into your landscape. I have other posts specifically about serviceberry, blueberries, and paw paw. Want to support birds? Read this post: Why Native Plants Matter for Birds.

Perhaps you were really wanting to do a pollinator garden this year. Take a look at my 3-part series on planning and implementing a pollinator garden. If you go to Part 3, it has links to Parts 1 and 2.

Shrubs are a layer of the landscape that occasionally need revisiting. Perhaps the conditions changed (sunny vs shady), they became too big for the space, or you just want to swap some out for native plants. This post on shrubs gives lots of ideas and links to many, many other posts about shrubs.

If you have another plant situation that needs ideas, drop a note in the comments and I’ll try to help.