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Washington Butterfly Association's Official Stand on Btk Spray for Gypsy Moths
March 2005
The Specifics:
The Washington State Department of Agriculture (WSDA) announced it is proposing to treat two locations this spring for the destructive European gypsy moth; a 200-acre site near Keyport in rural Kitsap County (basically the entire Evergreen Ridge housing development and several surrounding properties), and a 12-acre site in the Roanoke neighborhood in Seattle (boundary on the west; Eastlake Ave. E.: one the east, Boylston Ave. E.: on the north, approximately 125 feet north of Edgar St.: and on the south, approximately 290ft. south of E. Roanoke St.).
WSDA is proposing to treat the two sites with Bacillus thuringiensis var. kurstaki (Btk), a biological insecticide used in the past to keep the gypsy moth out of Washington. Btk is registered for use in the U.S. by the Environmental Protection Agency (EPA) and is found naturally in the environment. They plan on both aerial and ground spraying of Btk.
Background:
WSDA found 5 European Gypsy Moth adults each in 2003 and 2004 as well as 3 European Gypsy Moth egg masses and numerous pupal cases in 2004 at the Roanoke neighborhood site. At the Kitsap County site, WSDA found 1 European Gypsy Moth adult in 2003 and 5 adults in 2004. It found no other life stages in either year.
General Statement of Concern:
Although the Washington Butterfly Association (WBA) recognizes that the gypsy moth (Lymantria dispar L.) poses a serious threat to trees and supports the WSDA in its desire to contain the threat, WBA also has serious concerns about the use of Btk and WSDA's lack of thorough evaluation of alternatives. In particular, WSDA refers to a 1995 EIS to justify not using any alternatives.
Specifics of Concern:
Use of Btk:
Btk is lethal to Lepidoptera (butterflies and moths) resulting in an Order of insects being wiped out in the treated areas. Although Lepidoptera is the only order of insects that Btk will impact, this order is one of the most diverse, with numerous species in the proposed areas of Gypsy Moth control.
Jeff Miller, an entomologist at Oregon State University, in a report published in 2000, found a decline in Lepidoptera species abundance of between 80 and 100 percent and a decline in live caterpillar mass of between 84 and 99 percent, following aerial application of Btk. Although there is substantial recovery after three years, there is no evidence to indicate a complete recovery of all species to previous abundance. Or as Bob Pyle put it in a letter to the WBA board: "Areas sprayed by Btk have been shown to become virtual butterfly (and moth) barrens for years, thus affecting songbirds and bats up the food chain. The poor town neighborhoods that get it will likely lose their butterfly garden capacity for some time to come."
Alternatives:
Alternatives to Btk do exist. One of the best is a viral pathogen, known as Gypchek, was developed by the US Forest Service. A USFS web site describes how it works: "This pathogen invades through the gut wall, reproducing rapidly in internal tissue causing the disintegration of internal organs and the death of the host caterpillar. Eventually, the host ruptures, distributing viral oclusion bodies into the environment which serve to
infect other individuals." It has been found to be extremely effective. The one downside is cost, which is appears to be one reason that WSDA does not consider using it. The key benefit of Gypchek versus Btk is that Gypchek targets only gypsy moths. According to the USFS, it is currently used in limited quantities for suppressing gypsy moth outbreaks.
Conclusion:
WSDA appears to be set in its use of Btk without fully considering the alternatives. The justifications for using Btk (which kills all moths and butterflies) instead a more specific remedy (for instance, Gypchek) are unclear. However they appear to include cost. One way to bring the cost down is to start using Gypcheck. In the short term using Gypchek may be more expensive, but if it achieves the same goal, eradication of Gypsy
Moths, without killing so many other beautiful and important butterflies and moths, then it is obvious that the initial cost is worth it. The Washington Butterfly Association urges the WSDA to take the lead in developing better ways to eradicate Gypsy Moths.
More information is available at the WSDA web site about
WSDA Proposed Eradication Efforts.
Comments on this effort may be made to the WSDA by March 31, 2005:
Chad Hurshel Phillips, Eradication Coordinator
Washington State Department of Agriculture
Laboratory Services Division
3939 Cleveland Ave SE
Olympia WA 98501
Desk Phone 360-586-8456
Hot Line 1-800-443-6684
FAX 360-586-8509
CPhillips@agr.wa.gov
Usually agencies will take comments by email.
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