In Defense of Nature

 

Alien Plants Benefit the Environment

A native Eastern Tent Caterpillar feeding upon an alien Multiflora Rose shrub in Albemarle County, Virginia.

ALL TEXT AND PHOTOS © Marlene A. Condon

 Originally published in The News-Virginian (Waynesboro, Virginia daily newspaper) on October 27, 2022

 

https://newsvirginian.com/opinion/columnists/condon-many-alien-plants-benefit-the-environment/article_5d18e73c-557c-11ed-8f02-8375034e2011.html

 

On June 8, 2011, the journal Nature published a commentary by 19 ecologists who urged conservationists to “assess organisms on environmental impact rather than on whether they are natives”.

 

https://www.nature.com/articles/474153a

 

“Classifying biota [the plants and animals of a region] according to their adherence to cultural standards of belonging, citizenship, fair play and morality does not advance our understanding of ecology [the relations of organisms to one another and to their physical surroundings]. Over the past few decades, this perspective has led many conservation and restoration efforts down paths that make little ecological or economic sense”.

 

This other side to the story regarding alien species—in particular, nonnative “invasive” plants—is rarely publicized, yet it needs to be. It’s been eleven years since this essay appeared and was ignored by virtually everyone. As a result, the general public, government at every level, scientists, the media, and especially environmental groups and the people that support them have now instituted a scorched-earth policy that’s bringing about much destruction of viable habitat and the poisoning of our environment via herbicides.

 

Many people fervently believe that so-called invasive alien plants pose a dire threat to native insects, undoubtedly due to the 2007 book, Bringing Nature Home, by entomologist Doug Tallamy. In it, he wrote that “scientists who know what they are talking about” developed “an extensive body of theory” that predicts that native plant-eating insects “should be able to eat only vegetation from plants with which they share an evolutionary history”.

 

This assertion, which holds that herbivorous insects eat only those plants they have co-evolved with under the same environmental circumstances, sounds logical to the uninitiated. However, it disintegrates under scrutiny.

 

Dr. Tallamy tells us that these 6-legged critters that feed upon plant tissues are limited to feeding upon “no more than a few plant lineages [a single line of genetic descent through time]”, thus making them “specialists”. However, each plant lineage can include hundreds, if not thousands, of species around the world—which means an insect is likely to be able to feed upon at least some of the plants that are related genetically, regardless of their country (geopolitical boundary) of origin.

 

In other words, specialist insects aren’t usually limited to just one plant species, contrary to what this University of Delaware professor would have his readers believe. Because we know that countries share plant lineages (and even some species), phytophagous (herbivorous) insects should be able to eat vegetation from other areas on the Earth even though they evolved in concert with only some of the plant species in a lineage—and, indeed, they do.

 

In Bringing Nature Home, Doug Tallamy recounts the plight of native Eastern Tent caterpillars (Malacosoma americanum) that ran out of cherry leaves on a tree too small to feed them adequately. He mentions that leaves were still available to the caterpillars in the form of a Japanese Honeysuckle vine (Lonicera japonica) that had climbed the little tree, but he points out that the caterpillars “had not taken a single bite out of the alien plant…even in the face of starvation”.

 

This tale gives the reader the impression that the caterpillars could have eaten the honeysuckle if only it had been native, thereby having evolved with the insect. He does not point out that the caterpillars would have faced starvation even in the presence of a native vine, tree, or shrub if—like the alien honeysuckle—it wasn’t a member of the Rose Family, as is this caterpillar’s preferred native host plant, the cherry.

 

Several native Eastern Tent caterpillars feeding upon an alien Multiflora Rose shrub in Albemarle County, Virginia.

I have documented myself tent caterpillars feeding on a relative of the cherry—a nonnative, unevolved with, and much despised Multiflora Rose (Rosa multiflora) growing at the base of a leaf-stripped Black Cherry tree (Prunus serotina).  A factuality is that you can find native insects feeding upon nonnative plants, but, of course, you need to look!

 

People have been manipulated into believing alien plants serve no ecological purposes in the environment, when, in fact, they very much do, in very many ways, for innumerable insect (and other) species. As the 19 ecologists wrote in their paper, “[A] valuable step would be for scientists and professionals in conservation to convey to the public that many alien species are useful”, and that “Natural resource agencies and organizations should base their management plans on sound empirical evidence and not on unfounded claims of harm caused by nonnatives.”

 

Amen.

 

 

NATURE ADVICE:

 

Don’t remove alien plants just because they are alien plants. If you see critters using them, ask yourself if putting in new plants will immediately provide as much food and shelter/nesting sites as the nonnative plants presently there, or will it take many years for the new plants to provide habitat. Plant natives where you are increasing the amount of habitat on your property, rather than where you are destroying it.