The Soybean Aphid in North America Background and Biology David Voegtlin Center for Economic Entomology Illinois Natural History Survey Champaign, Illinois Latitude Bridge Program 5 February 2004

Another Exotic Immigrant In late July 2000 large colonies of aphids were being discovered on soybeans in southern Wisconsin and northern Illinois. In early August specimens from both Illinois and Wisconsin were received at the Illinois Natural History Survey for identification. They were compared to slides of Aphis glycines from China in the collection there and determined to be the same species.

The identification of a new exotic, especially one that feeds on a major crop is not a trivial matter. Microscope slide mounted specimens were sent to the USDA lab in Maryland, the CNC in Ottawa, the British Museum in London and the Florida Dept. of Agriculture in Gainesville. Each of these has an aphid specialist. Another Exotic Immigrant

All of the aphid specialists confirmed the determination. Following receipt of these confirmations a news release in both Wisconsin and Illinois alerted the public to the presence of a new soybean pest. By the end of August the aphid had been confirmed in Minnesota, Iowa, Missouri, Indiana and Michigan in addition to Wisconsin and Illinois.

When did the soybean aphid arrive in N.A.? - No evidence of aphid prior to No specimens collected in traps. - No specimens collected from soybeans. - A consultant in Wisconsin noted aphids on soybeans in 1995 but no specimens were collected. - First suction trap catch in central Illinois in late July 2000 Another Exotic Immigrant

Aphis glycines native to China, Korea and Japan now spread to Taiwan, Philippines, Australia, Canada, United States

Potential Importance Previously no aphids in North America that consistently colonized and developed large populations on soybeans. Cause for concern because of the potential impact of direct feeding by large populations and its potential as vector of both persistent and non- persistent viruses.

A fundatrix B aptera (e) C spring migrant D aptera E alata (e) F gynopara (e) G male H ovipara (e) I egg

Summer hosts (secondary hosts) In the field Glycine max, Glycine soja & other Glycine spp. In the lab Trifolium incarnatum - crimson clover Trifoium pratense - red clover Phaseolus coccineus - scarlet runner bean Hill, Hartman, Li in press Winter hosts (primary hosts) Rhamnus cathartica - exotic European Rhamnus davurica - exotic Asian Rhamnus japonica - exotic Asian Rhamnus alnifolia - native mid-western US Voegtlin, O’Neil, Graves in press

Rhamnus catharticaEurope, Asia Rhamnus frangulaEurope, Asia, Africa cultivar: asplenifolia cultivar: columnaris Rhamnus carolinianasoutheastern U.S.A. Rhamnus alnifolianorthern U.S.A. Rhamnus lanceolataeastcentral U.S.A. Rhamnella franguloidesAsia Hovenia dulcisAsia Berchemia scandenssoutheastern U.S.A. Ceanothus americanuseastern U.S.A. Voegtlin, O’Neil, Graves in press Potential Winter Hosts - Tested

Host Tests Autumn 2002, 03

Map by Rob Venette Univ. Minnesota

Suction Traps eight locations operated May - mid October samples collected weekly sent to INHS for sorting counts of soybean aphid placed on web site

Free. DeK. Mon. Urbana Perry Brown. Dixon Spr. 27 July August August August August August Sept Sept Sept Sept Oct Oct Suction Traps

Free. DeK. Mon. Urbana Perry Brown. Dixon Spr. 19 July July August August August August August Sept Sept Sept Sept Oct Oct Suction Traps

Free. DeK. Mon. Eur. Urbana Perry Brown. D. Spr. 4 July July July July August787 6, August1,9124, , August1, ,4031, ,5601, August1, , , , August , Sept Sept Sept Sept Oct Oct Oct.0005n.s.154 Suction Traps

Late Sept. Early Oct. Trap Catches 2002 DeKalbMonmouthUrbanaPerry 20 Sep 017 (17, 0)02 (2, 0) 27 Sep 2 (2, 0)80 (78, 2)71 (70, 1)284 (284, 0) 4 Oct 38 (31, 7)62 (17, 45)13 (9, 4)133 (112, 21) 11 Oct 7 (0, 7)3 (0, 3)4 (1, 3)9 (0, 9) (gynoparae, males)

Timing of spring and fall migrations Observations made of natural populations show the presence of spring migrants on Rhamnus in April- early May (central and northern Illinois). This is often ahead of the planting and emergence of soybeans in the area. Observations made in the autumn show the arrival of gynoparae and males (fall migrants) on Rhamnus in the last part of September and October (central and northern Illinois). This is usually after the majority of the beans has been harvested in the area.

Movement Questions How far will the spring migrants from Rhamnus fly? - No spring infestations in soybeans have been related to a spring population on Rhamnus. - Suction traps have not picked up spring migrants. How far do winged aphids that develop on soybeans in the summer fly? - The rapid spread since its introduction and finding the aphid in West Virginia in 2000, Georgia and Mississippi in 2002 suggest that some individuals are carried great distances.

Distribution at end of 2002/03 reaching limits of soybean growing region in the United States. Not shown is the distribution in Canada but it has been found in Manitoba, Ontario and Quebec Southern spread may be limited by biology, specifically the presence of suitable over-wintering host plants.

General Observations Aphis glycines appears to have many attributes of an excellent pest. - Ability to spread very rapidly - High reproductive capacity - Ability to vector plant diseases - Can tolerate wide range of climatic conditions Weak spots in the armor of A. glycines are: - limited distribution of primary hosts - phenology of migration in relation to planting and harvesting of soybeans - limited secondary host range