2. Methods
2.1. Rearing
Soybean plants var. 92B16 (Pioneer Hi-Bred International Inc., Johnston, IA) were maintained in a green house at 24 °C on a 16:8 h L:D. Soybean aphid was cultured on soybean in a walk in growth chamber (Percival Scientific, Perry, IA) at 24:16 °C on a 16:8 h L:D. The
predatory midge,
A. aphidimyza
, was obtained from IPM
Laboratories (Locke, NY) as pupae. Flies were hatched
by placing the pupae into a dark growth chamber for 48 h
at 24 °C. Adults were released onto soybean aphid-
infested soybean plants and allowed to lay eggs. Larvae
hatched within 3 d and reached their second instar within
5 d. The aphid predator
C. carnea
was obtained from
Koppert Biological Systems (Ann Arbor, MI) as eggs and
W
rst instar larvae. The eggs and larvae were placed in rear-
ing boxes on soybean plants infested with
A. glycines
. A
culture of
H. axyridis
was initiated by
W
eld-collecting
adult beetles from soybean
W
elds at the Michigan State University Beet and Bean Farm (Saginaw, MI); larvae
and adult
H. axyridis
were reared separately on soybean
aphid-infested plants. All predator colonies were main-
tained at 24:16 °C on a 16:8 h L:D.