Soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae): A new pest in the Red River Valley of the north

The soybean aphid, Aphis glycines (Matsumura), is an Asian soybean pest that has rapidly invaded the United States. Because A. glycines is a recent pest in the United States, a comprehensive, integrated management approach to control this aphid has yet to be developed.;In an overwintering study conducted in 2005 and 2006, overwintered egg survivorship was nearly 100% in both years. Additionally, successful reproduction on the overwintering host plant, buckthorn (Rhamnus), and migration of A. glycines from Rhamnus in woodlots and shelterbelts to soybean was documented in the spring of both years. The date of first eclosion of soybean aphid in the overwintering study was 10 April in 2005 and 12 April in 2006. The migration of alate females from Rhamnus to soybean beginning on 15 and 17 May, 2005 and 2006, respectively, coincided with leaf development on soybean plants ranging from cotyledon to second trifoliate development stages in nearby soybean production fields.;A second set of experiments was conducted using the electrical penetration graph (EPG) technique to ascertain the effects of 'Dowling' on A. glycines' feeding behavior. The electrical penetration graph (EPG) recordings showed that soybean aphids had difficulty penetrating the sieve tube elements, resulting in the inability of soybean aphid to feed successfully on phloem.;The final component of this dissertation examined the tritrophic effects of 'Dowling' on the parasitoid wasp Aphidius colemani when it fed on the soybean aphid. In a series of choice tests, A. colemani parasitized soybean aphid feeding on 'Dowling' and a susceptible check ('Glenwood') equally, suggesting no effect of resistance on parasitoid oviposition preference. Results from no-choice tests indicated that development time and survival of A. colemani that developed in aphids that fed on 'Dowling' did not differ from those individuals that developed in aphids on 'Glenwood'. However, weights of adult male A. colemani developing in aphids feeding on 'Dowling' were reduced compared to the weights of adult males that developed in aphids which fed on 'Glenwood'. Additionally, the sex ratio of wasps reared in 'Dowling'-fed aphids was strongly biased towards males compared to wasps reared in 'Glenwood'-fed aphids.