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Battle Renewed in South Dakota Soybean Fields
By Don Comis
August 12, 2003
The first aphid to colonize U.S.
soybean plants has now spread as far west as South Dakota. Originating in Asia,
the Chinese soybean aphid, Aphis glycines, was first detected in U.S.
soybean fields in Wisconsin in 2000. Now the aphid is in 16 states, the latest
being South Dakota, where it arrived in 2001.
Agricultural Research Service plant physiologist Walter Riedell and
entomologist Louis Hesler have joined forces with South Dakota State University
(SDSU) graduate student Eric Beckendorf and
with Michael Catangui, of the SDSU Cooperative State Extension Service. Their
goal: to protect American soybeans against a foe the plants' ancestors have
faced in Asia for thousands of years. Riedell and Hesler are with the ARS'
Northern Grain Insects Laboratory
in Brookings, S.D. This research, partly funded by the South Dakota Research
and Promotion Council, is in cooperation with other ARS locations and
universities throughout America's soybean belt.
Riedell and Beckendorf are placing aphid-filled cages over soybean plants to
determine how many aphids it takes to do serious damage at each stage of the
plants' growth. From this, they will determine when farmers should spray to
Chinese soybean aphids are particularly prolific, with newborns able to bear
young in just one week. This summer, Beckendorf has seen the population in one
cage of aphids explode from 10 insects to 1,000 in two weeks.
One question that's arisen is whether the aphid's ancient enemy, the
ladybug, can keep the aphid in check. Hesler is surveying to see which species
of ladybugs colonize soybeans. So far he's found that the Asian ladybug,
European seven-spotted ladybug and native convergent ladybugs do.
ARS is the USDA's chief scientific