The Soybean Aphid in North AmericaBackground and Biology

David VoegtlinCenter for Economic EntomologyIllinois Natural History SurveyChampaign, Illinois

Latitude Bridge Program5 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

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 2000. - 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 fundatrixB aptera (e)C spring migrantD apteraE alata (e)F gynopara (e)G maleH ovipara (e)I egg

Summer hosts (secondary hosts)In the fieldGlycine max, Glycine soja & other Glycine spp.In the labTrifolium incarnatum - crimson cloverTrifoium pratense - red cloverPhaseolus coccineus - scarlet runner bean

Hill, Hartman, Li in press

Winter hosts (primary hosts)Rhamnus cathartica - exotic EuropeanRhamnus davurica - exotic AsianRhamnus japonica - exotic AsianRhamnus alnifolia - native mid-western US

Voegtlin, O’Neil, Graves in press

Rhamnus cathartica Europe, AsiaRhamnus frangula Europe, Asia, Africa

cultivar: asplenifoliacultivar: columnaris

Rhamnus caroliniana southeastern U.S.A.Rhamnus alnifolia northern U.S.A.Rhamnus lanceolata eastcentral U.S.A.Rhamnella franguloides AsiaHovenia dulcis AsiaBerchemia scandens southeastern U.S.A.Ceanothus americanus eastern U.S.A.

Voegtlin, O’Neil, Graves in press

Potential Winter Hosts - Tested 2002 - 2004

Host Tests Autumn 2002, 03

Map by Rob VenetteUniv. 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 82 5 6 1 2 0 0

3 August 149 55 5 0 5 0 010 August 886 262 2 1 0 1 017 August 32 21 3 0 1 0 124 August 2 0 0 0 0 1 031 August 0 1 0 0 0 0 0

7 Sept. 0 0 0 0 0 0 014 Sept. 0 0 0 0 0 0 021 Sept. 5 0 0 3 0 0 028 Sept. 3 1 4 0 0 0 0

5 Oct. 2 2 0 0 0 3 012 Oct. 0 0 0 0 0 0 1

Suction Traps - 2001

Free. DeK. Mon. Urbana Perry Brown. Dixon Spr.

19 July 3 0 3 0 4 0 026 July 3 3 10 0 0 0 0

2 August 41 5 6 6 0 0 09 August 13 19 8 0 5 0 016 August 22 8 0 2 10 0 023 August 0 4 0 0 2 1 030 August 0 0 0 0 1 0 0

6 Sept. 0 1 0 0 0 0 013 Sept. 0 0 3 0 0 0 020 Sept. 0 0 17 0 2 0 027 Sept. 0 2 80 71 284 1 0

4 Oct. 0 38 62 13 133 1 011 Oct. 0 7 3 4 9 0 0

Suction Traps - 2002

Free. DeK. Mon. Eur. Urbana Perry Brown. D. Spr.

4 July 0 0 0 0 0 0 0 011July 21 1 0 0 0 0 0 018 July 176 131 1 2 0 0 0 025 July 112 940 59 142 2 4 3 1

1 August 787 6,755 71 401 9 8 1 08 August 1,912 4,980 569 4,920 163 232 18 015 August 1,810 286 1,403 1,090 602 1,560 1,535 31 22 August 1,347 264 2,690 921 1,131 620 4,113 229 August 26 29 209 50 215 85 1,060 67

5 Sept. 1 3 8 2 6 3 251

12 Sept. 0 0 0 0 0 0 0 00

19 Sept. 0 0 1 1 0 0 0 00

26 Sept. 0 0 0 0 0 0 0 00

3 Oct. 0 0 0 0 0 0 0 010 Oct. 0 0 0 3 0 2 0

017 Oct. 0 0 0 5 n.s. 1 5

4

Suction Traps - 2003

Late Sept. Early Oct. Trap Catches 2002

DeKalb Monmouth Urbana Perry

20 Sep 0 17 (17, 0) 0 2 (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