Category Archives: Weeds

Atteva aurea

Atteva aurea is a cute little moth that feeds as a larva on the introduced ornamental tree, Ailanthus

Atteva aurea on wall of gas station Martin, TN - 10 July 2013

Atteva aurea on wall of gas station Martin, TN – 10 July 2013

altissima, in the Eastern U.S. and Canada.  Ailanthus altissima is from the orient, so I had always assumed the moth that feeds on it was too. The real story is much better.

As Vitor Becker explains in “A review of New World Atteva Walker moths (Yponomeutidae, Attevinae)”:

The presence of aurea in the eastern United States and Canada and its association with Ailanthus altissima (Mill.) (Simaroubaceae) is an interesting subject to be investigated. This plant is an ornamental introduced from Asia and now considered one of the most serious weeds in the United States. It was first planted near the University of Pennsylvania, Philadelphia, in 1784 (W. Thomas, pers. comm.) and from there it spread over the entire country. Once it reached southern Texas, where presumably aurea was already present, the moth started to move north. By 1856 it had reached Georgia, as indicated by the material described by Fitch (1856: 486). Riley (1869: 151) found it common in Missouri, feeding on ailanthus. These records indicate that this showy and common moth was absent in the region before the introduction of Ailanthus, and the approximately 70-year gap between the introduction of the host, to the first record of the moth by Fitch, is the time it took the plant to move south and the moth to move north.”

Ailanthus altissima is in the plant family Simaroubaceae.  The native hosts that A. aurea is known to use are: Castela peninsularis, C. polyandraC. emory, Simarouba amara and S. glauca – all in the family Simaroubaceae. So an introduced plant from the orient helped a tropical moth to colonize eastern North America. A much different story than I originally thought.

What does Languria mozardi eat anyway?

I know this question is a central issue that keeps most of you up at night, but it was bothering Kelly Tindall, Cory Cross, and myself. We found Languria mozardi tunneling in soybean stems and were curious as to why we found this native insect in a non-native plant. This was especially interesting to us as another stem-boring beetle, Dectes texanus, is also a native beetle that has made a switch from boring native plants in the family Asteraceae to boring stems of non-native plants in the family Fabaceae.

As we read the literature on the plants used by L. mozardi, we found things that just did not seem right. The primary clue was: Languria mozardi was using plants that didn’t exist! We then went back to the source material to try and figure out exactly what was the case for this insect. To make a long story short, by not using consistent criteria and terminology 48 plants were listed as host plants for L. mozardi when only 13 were actual developmental hosts.

So we critically thought about how insects (especially L. mozardi) use plants, then came up with a way of evaluating the source literature, then slugged our way through all the source literature, and finally developed a little paper to report our results:  Fothergill, K., K.V. Tindall, and C.B. Cross. 2013. What is a host plant? Plants used by Languria mozardi Latreille 1807 (Coleoptera: Erotylidae): a review. Pan-Pacific Entomologist 89.1:43-59.

Gardener Beware

Just because it comes in a seed packet doesn’t mean it suitable for your garden. These 050224seedspackets are full of noxious, non-native plants. Mr Fothergill’s Wildlife Mixture Wildflower packet would be fine if I planted it in England – every plant listed on the packet is listed as noxious in one of the 50 contiguous states. The Kudzu vine was packaged out of California. Kudzu is a beautiful, great-smelling plant or is a green hell – it all depends on point of view (and how noxious your state weed board views the plant).

Consider gardening with native plants. You may plant an unruly native, but you won’t plant an ecological disaster. Just something to consider when shopping for plants this spring.

Weed management

Since the last couple of posts have dealt with weed management/ biocontrol weevils, I thought I

Ol' Cirsium vulgare is in for an ass kicking today!

Ol’ Cirsium vulgare is in for an ass kicking today! Idaho July 2012.

might post about some weed control paradigms. The photo at left shows me at work managing weeds at a mine exploration site in a National Forest utilizing perhaps the most expensive weed control methodology known: a trained botanist unleashed on a low density weed. As readers of the blog are aware, Rhinocyllus conica will feed on this noxious weed species, but removal before pollination guarantees that no seed will be set by this individual plant. The intensity of human response to weed threats is correlated to what is being protected and potential for effecting change. This is true whether the weeds are in wildland or agricultural situations. The area in the photo is a zero tolerance zone for weed occurrence due to sensitive nature of native plant populations and the economic activity occurring on site.

Amazingly, I have had people tell me that I shouldn’t kill plants. A blood-(sap)-thirsty approach approach to invasive species shows that I am not in tune with Mother Nature (who sent these species to tell us something) this is a statement I have heard more than a couple times. However, I have seen: wetlands become a monoculture of Lythrium salicaria, sage steppe converted to a sea of Bromus tectorum, and bean fields not harvested due to Amaranthus palmeri; to do nothing and just let these plants have their way with our ecosystems is something I just cannot do. This isn’t to say I don the weed management cape and tights every time I see noxious weeds – if I did they would never come off. So, what can we do?

  1. Learn your plants. Until you know your targets you are just a green murderer.
  2. Learn how to prevent movement of noxious weeds: clean seeds from your socks, vehicle undercarriage, etc.
  3. Clean up your yard, that Lonicera japonica bush isn’t as beautiful as you think…
  4. Be aware that many invasive plants (e.g. Lonicera japonica) will support some native wildlife, try to replace that function with native plants as the invasive is removed.
  5. Report populations of noxious plants to land managers when on public lands. GPS data, photographs, and specimens will all help land managers to act.

Pass me the glyphosate please…

A little more about Rhinocyllus conicus

In the previous post, I mentioned that Rhinocyllus conicus was a bad player as it liked all thistles. I

Rhinocyllus conicus, collected from artichoke, 5 August 2012, Twin Falls, Idaho, USA

Rhinocyllus conicus, collected from artichoke, 5 August 2012, Twin Falls, Idaho, USA

was lurking in our household entomology lab, when I remembered that I had collected weevils off of the two artichoke plants I was trying to grow in our garden last summer – sure enough Rhinocyllus conicus! So, we brought R. conicus to the USA to mess up my artichoke crop?? Being as this weevil and the thistle it is supposed to control can be super common, this species can be put in the not a successful biocontrol introduction.

It is still a pretty cool weevil.

Mecinus janthinus

This week Lance brought some Linaria dalmatica (Dalmatian toadflax) stems into work to check on

Mecinus janthinus

Mecinus janthinus

weed control efforts. By dissecting the stems Lance was able to find 30 – 100 adult weevils, Mecinus janthinus, in each stem! These 3mm long weevils are part of an old and oft-repeated story where an introduced pest species is reunited with the species that control it in its’ homeland – this is one form of what is called biocontrol. In this instance it will be a successful story from the initial release of 200 insects five years ago to the build up of a robust insect population – that actually kept the toadflax plants in the area of interest from flowering!

The toadflax plant population in the area may crash (good riddance to a noxious weed – but the weevils will have to seek new toadflax patches) or weevil and toadflax will persist at some low level. Either way control of an exploding non-native plant was achieved with a little help from the old country. This isn’t to say you should fear no weevil, Rhinocyllus conicus, a weevil introduced to control Carduus nutans is also a weevil with a taste for native thistles also and may have implications in restoration of Calephelis mutica, the swamp metalmark, as it reduces populations of this butterfly’s larval food plant.

In this instance, the weevil is hard working, hasn’t strayed from the task, and is capable of going places difficult to get to with a backpack sprayer of herbicide. It will be interesting to see what the future holds.