Submitted to: Journal of New York Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2000
Publication Date: 11/15/2000
Citation: Day, W.H., Tilmon, K.M., Romig, R.F., Eaton, A.T., Murray, K.D. 2000. Recent range expansions of Peristenus digoneutis, a parasite of the tarnished plant bug, and high summer temperatures as a factor limiting its geographic distribution in North America.. Journal of New York Entomological Society. 108:326-331. Interpretive Summary: The tarnished plant bug (TPB), Lygus lineolaris, is one of the most injurious insects in the United States. It damages many different vegetable, fruit, and seed crops, cotton, and forestry seedlings. W. H. Day established a small parasitic wasp, Peristenus digoneutis, in NW New Jersey in 1984. As the parasite increased, he subsequently determined (1996) that it sharply reduced TPB numbers in alfalfa, and cooperators hav recently found it attacking the TPB in strawberries, a high-value crop. This paper documents P. digoneutis' spread from 1997 through 1999; we have now found it in 50 counties, in 8 northeastern states. The map shows researchers where the parasite is present (so new research can be started), where the parasite probably is (so field survys can be made, to be certain) and where the parasite has not been found. Our data also show that the present range of the parasite appears to be limited by high summer temperatures; we then determined that it does not occur south of plant hea zone 4 (maximum 30 days of 30 C or more, per year). This information tells us that the parasite will provide biological control of the TPB only north of New York City (latitude 40.5N), and will likely spread to the north and west into important vegetable and fruit-growing areas of the northern U.S., and of Ontario and Quebec.
Technical Abstract: Peristenus digoneutis was discovered in one new state (Maine) and in 14 new counties in ME, NH, NY, PA, and VT during 1997-1999. These new records increased the area where this parasite has been found by 39%, to a total of 50 counties in eight states. No permanent establishments of P. digoneutis have been found south of New York City, which indicates that high summer temperatures are probably limiting its spread southward. A good agreement was found between the parasite's southernmost establishment locations and a maximum summer temperature/duration of 30 C (86 F) for 14 to 30 days. This temperature limit suggests that P. digoneutis can disperse westward both north and south of Lake Erie, across southern Ontario and northern Ohio, to Michigan and Wisconsin. Establishment south of New York City (latitude 40. 5 N) is unlikely, except possibly along the higher/cooler elevations of the Appalachian Mountains.