Dr. Rob Dillon, Coordinator

Friday, June 21, 2002

Freshwater Gastropod Pests, Continued...

My 5/23 message on the subject of pest snails brought an interesting response from David Richards, research ecologist with EcoAnalysts Inc and Ph.D. student at Montana State. He called my attention to a really impressive Potamopyrgus web site being developed at MSU - Bozeman. The site is "70% ready for public use" according to David (as of late May), but many of the resources are already spectacular. Check out the "Mudsnail Maps" at: http://www.esg.montana.edu/aim/mollusca/nzms/

Potamopyrgus antipodarium is not, alas, on the draft list of pest gastropods currently being circulated by Rob Cowie, the AMS Conservation chair. You may recall the allusion I made last month to a collaboration between the USDA and the AMS aimed at identifying "America's Least Wanted Mollusks." Not only is it difficult to document an economic impact for Potamopyrgus, it's also probably too late to do much about it.

But there are certainly many other pest gastropods whose introduction to North America may yet be prevented, including a couple freshwater groups. The message from Rob Cowie appended below is self-explanatory. Please consider responding to him. Or meet him, and the rest of the Pest Mollusk Committee, and David Richards, here at AMS 2002 in August!

--------- [Begin message from cowie@hawaii.edu] ---------

To all Researchers interested in the impacts of alien species:

I am sending this message out in the hope of getting feedback from people not only in the USA, but also from throughout the world.

The United States Department of Agriculture (USDA) has asked me (through the American Malacological Society) to create a list of 15 non-marine molluscan taxa that the USA should consider of paramount quarantine importance. That is, these are taxa either not yet in the USA or if they are in the USA they are confined, as yet, to only a few localities where it may be possible to eradicate them or at least to prevent them from spreading further afield. The list will eventually be accompanied by "factsheets" on each taxon in an American Malacological Society report to the USDA*.

The first step is to create the list. Working together, David Robinson, Rob Dillon and I (with Jim Smith of USDA providing guidance) have come up with the following list. We decided it was not possible to come up with just 15 species (the initial USDA request), so we have come up with groups of species belonging to 15 families. These taxa were selected based on 13 criteria that in general are thought to correlate with potential invasiveness. These criteria include biological features of the taxa (e.g., reproductive rate, body size) as well as features reflecting their interaction with humans (e.g., pest status elsewhere, frequency of interception by quarantine officials). Our method of scoring each taxon against the criteria is as yet very rudimentary.

I would very much welcome comments about this list, especially regarding any glaring omissions of taxa that you know to be serious invasive pests elsewhere in the world? [But remember, there are many pest species that are not on this list because they are already widespread in the USA.] Here's the list, with the most important taxa first:
  • Veronicellidae - especially Sarasinula plebeia and Veronicella cubensis, but also Laevicaulis alte and Diplosolenoides occidentalis. Agricultural pests.
  • Ampullariidae - especially Pomacea species (except Pomacea bridgesii), but also Pila species and Marisa species. Rice (and other aquatic plant) pests, and likely environmental pests damaging native aquatic vegetation.
  • Helicidae - especially Theba pisana and Eobania vermiculata, but also Cantareus apertus, Otala punctata, and perhaps Helix species (remember Helix aspersa - or whatever genus you consider it to be in now - is already widespread in the USA). Agricultural and garden pests.
  • Achatinidae - especially Achatina fulica, but also Archachatina marginata, and perhaps Achatina achatina. Agricultural and garden pests and general nuisances; also, as with many snail species on this list, can vector serious human parasites.
  • Hygromiidae - especially Cernuella species, Cochlicella species, and Xerolenta obvia. Agricultural pests.
  • Planorbidae - especially Indoplanorbis exustus, and to a lesser extent Biomphalaria species. Vectors of animal schistosomes not yet in the USA.
  • Milacidae - Tandonia budapestensis and Tandonia sowerbyi, and to a lesser extent, T. rustica. Crop pests.
  • Enidae - various species. Vectors of livestock diseases.
  • Succineidae - Succinea tenella/horticola, possibly also non-US Calcisuccinea species. Agricultural/horticultural pests. Contaminants of horticultural products.
  • Pleurodontidae - Zachrysia provisoria. Agricultural pest.
  • Helicarionidae - Ovachlamys fulgens and Parmarion martensi. Pest potential not fully appreciated, but contaminants of horticultural products and spreading very rapidly around the world.
  • Arionidae - Arion lusitanicus. Agricultural pest, general nuisance.
  • Urocyclidae - Elisolimax flavescens.
  • Bradybaenidae - Acusta touranensis.
  • Spiraxidae - Euglandina species (except E. rosea, which is native to the south-east USA). Predators of native snails.
Many thanks for any input you care to offer. Your help will be duly acknowledged in the final product.

Robert Cowie
Center for Conservation Research and Training
University of Hawaii
3050 Maile Way,
Gilmore 408
Honolulu, Hawaii 96822 USA

*Historical Note:
The paper for which this survey was compiled in 2002 was ultimately published in 2009:

Cowie, R. H., R. T. Dillon, D. G. Robinson and J. W. Smith (2009) Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment. American Malacological Bulletin. 27: 113-132. [PDF]