Keep an eye out on your soybeans for soy bean aphid as they have been
found in MI See following message from Dr. Chris DeFonzo.

Here is a photo of one



-----Original Message-----
From: Field Crops AOE [mailto:[log in to unmask]] On Behalf Of
Chris DiFonzo
Sent: Friday, June 01, 2007 7:57 AM
To: [log in to unmask]
Subject: SBA found in Michigan


Soybean aphids were found on soybean in Michigan yesterday in Berrien 

County (Mike Staton wins the box of freezie-pops), on the MSU campus, 

and at the Bean/ Beet Farm in Saginaw.  Infestation is less than 1% 

at each location. Ants on plants really help to key in on colonies.


Here is an excerpt from Kathleen Delate's research from Iowa State Univ
of an overview of the insect pest.

The soybean aphid (Aphis glycines Matsumura)

is native to China and Japan, and was a new pest

in Iowa in 2000. Aphid numbers were high in

the 2001, but in 2002 and 2003, aphids appeared

to be less of a problem. This small, yellow aphid

has distinct black cornicles ("tailpipes") on the

tip of the abdomen and develops colonies on

soybean plants as winged and wingless forms.

Aphids feed through piercing-sucking

mouthparts. The winged form has a shiny black

head and thorax with a dark green abdomen and

black cornicles. The soybean aphid is the only

aphid in North America that will reproduce on

soybeans. Therefore, any small colony of aphids

found on soybeans must be soybean aphids. The

aphid may have up to 18 generations a year,

beginning with overwintering eggs on the

alternate host of buckthorn trees. These eggs

hatch into nymphs and two generations of

wingless females develop on buckthorn, before

the winged generation flies to soybean fields in

the spring. Winged generations appear on

soybean plants in the case of crowding from

wingless colonies, and in the fall, a winged

generation migrates back to buckthorn. These

females produce a wingless generation that

mates with winged males and lay eggs on the

buckthorn trees. Soybean aphid populations

build and peak during the period between late

seedling stage to blooming stage. Usually in late

July, the aphids move from the terminal area of

the plant to the undersides, making control more

difficult. Honeydew and sooty mold (the

excrement of the aphid and the resulting black

fungus that grows on it) are apparent in August

and September. Stunted plants, reduced pods

and seeds may result from aphid feeding. Also,

soybean aphids can transmit viruses that cause

mottling and distortion of the leaves and a

reduced seed set. Discolored seeds may also

result from this infection.

An economic threshold of 250 aphids per plant

if the population is increasing and plants are in

the late vegetative or early (R1-R4)

reproduction stages has been established (ISU,

2004). This incorporates a seven-day lead-time

before the aphid population would be expected

to increase to 1,000 aphids per plant, which is

the economic injury level and the population

size that would be expected to cause economic

damage (i.e., yield loss that exceeds the cost of

control). There are several natural enemies that

help manage the aphid, including lacewings,

Asian lady beetles, and entomopathogens (fungi

that infect insects, causing a reddish-brown

appearance and death).



The Leopold Center offers some good biological approaches that can
compliment your treatments. Keep in mind when spraying any pesticide
(even if organic) it may impact beneficial insects as well as the
targeted pest.


Dr. Christina DiFonzo

Field Crops Entomology Program

Michigan State University

East Lansing, MI   48824


Mailing Address: 243 Natural Science Building

Office Address:  331 Natural Science Building


tel:  517-353-5328    fax:  517-353-4354


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