A Heavenly Little Moth?

Between the snow and some intractable data analysis, I didn't get out today, so I thought it's about time to put up a reminder of warmer weather to come:

Ailanthus Webworm Moth, (Atteva aurea), Zion, Lake Co, IL 8/19/2013

This is an Ailanthus Webworm Moth (Atteva aurea). (There is a related species in Europe with the same common name -- more on that in a bit.) Figuring out which species was which took some work, with DNA barcoding playing a leading role (1), but that's a tale for another day. Now, I'm more interested in how this little guy got his common name.

Ailanthus is a genus of plants in the family Simaroubaceae. One species, the Tree-of-Heaven (Ailanthus altissima), was introduced to the US from its native China back in the 18th century. The Asian Ailanthus Webworm Moth (A. fabriciella) is at times a notable pest on this and related trees (2). Our species of moth can be a pest on Tree-of-Heaven at times, but the tree is actually considered highly invasive, even as it's sold in nurseries.

The tree is introduced, but the moth is apparently native to south Florida and south Texas south to Costa Rica, where it's original host plants Simarouba glauca and S.amara are found. (A moth's host plants are those plants that the caterpillars are able to eat.) Both of these species are, not surprisingly, in the Simaroubaceae as well. So when Ailanthus reached Texas, it's probably not too much of a surprise that the moths were able to eat it as well. Both Simarouba  sp. are tropical plants, and have never spread north, so the moths never did either. But Ailanthus is from a more temperate climate, and grows well even into southern Canada. The moth follows it, although like many Lepidopterans, it probably doesn't survive northern winters, instead recolonizing areas every summer. Some years it can be quite common in the Chicago area, often active on flowers during the day as well as coming to lights at night.

So is this moth native, or introduced? It's dependent upon an introduced plant, and any impacts it's having on our local ecology are the result of that introduction, but no one, to our knowledge, moved them anywhere at all. For the moment, it appears that if we manage to eliminate the trees, then the moth will again be restricted to the southern edge of the country, but it's already jumped hosts once. Of course, it only jumped between closely related hosts, but other members of the same moth family (Yponomeutidae) are native to this area, feeding on apple trees, so it may not be that much of a stretch to imagine them switching again.

They are a stunning little moth, and they don't seem to cause any problems, so I guess this isn't really much of an issue, but it does illustrate how effects can ripple out from apparently innocent actions, and hints at just how much complexity an ecosystem can really be hiding, waiting for some poor graduate student to jump into.

 

(1) Wilson, J., Landry, J. F., Janzen, D., Hallwachs, W., Nazari, V., Hajibabaei, M., & Hebert, P. (2010). Identity of the ailanthus webworm moth (Lepidoptera, Yponomeutidae), a complex of two species: evidence from DNA barcoding, morphology and ecology. ZooKeys, 46, 41-60.

(2) Mathur, R. N., Chatterjee, P. N., & Sen Sarma, P. K. (1970). Biology, ecology and control of Ailanthus defoliator Atteva fabriciella Swed.(Lepidoptera: Yponomeutidae) in Madhya Pradesh. Indian Forester, 96(7), 538-52.