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Aphid
Flight Activity during week ending 29 June
Aphid numbers were low at all locations reported. Potato aphid were
captured at several locations. Potato aphid overwinters in the
Northern Great Plains and generally is the most common potato colonizing
aphid and virus vector found in potato during the early growing season.
Some cereal aphids, e.g., bird cherry-oat aphid and corn leaf aphid were
found. No green peach aphid were captured.
Trap locations for which data were not available when this page was
created will be updated as results are received.
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Status of soybean aphid
by
David Ragsdale, Professor of Entomology, University of Minnesota
An exotic aphid, the Asian soybean aphid, Aphis
glycines Matsumura, has been found in six counties in Minnesota this
spring (Houston, Ohlmsted, Wabasha, Goodhue, Winona, and Dakota). This
aphid was first reported in North America last summer. However, the
aphid appears to have been here for a few years as it was found in 10 North
Central states last year. In 2001 the aphid has been found in
Minnesota, Wisconsin, Iowa, Michigan, and Illinois. In Minnesota, the
counties listed above defines the eastern edge of the aphid infestation and
represents areas of the state where the soybean aphid likely overwintered.
As with most aphids, the overwintering host is a shrub or tree species.
The soybean aphid has been confirmed overwintering on buckthorn, Rhamnus
cathartica, in Illinois. Although we searched buckthorn in
Minnesota, we were unable to find this aphid on buckthorn, but the pattern
of aphids colonizing soybean this spring suggests local movement rather than
long distance movement. For example, field edges near woodlots
containing buckthorn is where soybean aphids could be found, while open
fields without wooded edges were lacking aphids.
Soybean aphid is colonizing very young plants in the two leaf stage.
We did observe field where heavy thunderstorms occurred when soybeans were
in the two leaf stage and where aphids were found on 20% of the plants, have
aphids almost wiped out following a 1.5" rain storm. Soybean
aphids colonize the growing point of the plant and are somewhat exposed to
the elements.
We are continuing to survey for soybean aphids and in collaboration with the
MDA pest survey crew we will be sampling soybean fields in counties west of
the Mississippi river this next week. We hope to devine the western
edge of the soybean aphid distribution.
I think within a week or so aphids on some of the most heavily infested
fields may begin to form winged individuals which may migrate out from these
early colonized fields. Winged aphids (summer migrants) have been
observed in Michigan this week with one field reported to have 22% of aphids
developing wing pads.
Three entomologists (Dr. David Ragsdale, Dr. George Heimpel and Dr. Zhishan
Wu) will be traveling to China, the native home of the soybean aphid, to
search for parasites of the soybean aphid. Their goal is to release
parasites of the soybean aphid that can control this exotic aphid
alleviating the need for soybean producers to control aphids on soybean.
Visit the following web sites to view up to date distribution maps.
http://www.mda.state.mn.us/pestsurvey/PestReports/PestReport.html
http://www.pmcenters.org/Northcentral/Saphid/aphidindex.htm
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