Cereal aphids (Hemiptera Aphididae) are important pests of wheat and can cause yield loss through both direct feeding injury and indirectly by transmitting viruses. Previous work has demonstrated that natural enemies are effective in suppressing cereal aphids in wheat fields in Europe and North America; however, no studies have been done in Michigan. The objectives of this thesis research were to characterize the natural enemy community in wheat fields and evaluate the role of different natural enemy groups in regulating cereal aphid population growth. I investigated these objectives in four winter wheat fields on the Michigan State University campus farm in East Lansing, Michigan. I monitored and measured the impact of natural enemies by experimentally excluding or allowing their access to wheat plants infested with cereal aphids. I found that the natural enemy community in the wheat fields consisted mostly of foliar-foraging and ground-dwelling predators with relatively few parasitiods. In combination, these natural enemy groups were very effective at reducing cereal aphid population. I also investigate the role of each natural enemy feeding guild (foliar-foraging versus ground-dwelling predators) independently. The result illustrates that ground-dwelling predators were more effective at suppressing cereal aphid populations than foliar-foraging predators in wheat fields. Overall, my research demonstrates the importance of biological control in in wheat and suggests that effective conservation of natural enemy communities can protect wheat from direct damaged caused by cereal aphids.
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