Monday, December 10, 2007 - 8:17 AM

Are Iowa prairies a source for soybean aphid (Aphis glycines) predators?

Wayne J. Ohnesorg, and Matthew E. O'Neal, Iowa State University, Entomology, 113 Insectary, Iowa State University, Ames, IA

There is growing interest in whether native, perennial habitats can serve as reservoirs and refugia for natural enemies of annual crop pests. In Iowa, prairies once covered the majority of the landscape, and there is a desire to reconstruct these habitats for the improvement of ecosystem services. We investigated the aphidophagous community within prairies if they contained species important for soybean aphid management, such as Coccinellidae. Prairies were selected based on distinct categories of restoration; 10 reconstructed prairies that had been seeded into agricultural fields, 11 native prairies that had not been seeded into, and 10 reconstructed prairies adjacent to native prairies. Prairies were selected by these categories to account for variations in habitat quality and subsequent community associations. During 2006 and 2007 prairies were sampled for aphid predators using sweep nets. Sampling was conducted weekly on 3 sites while the rest were sampled once a month. We found 33 species or families considered predators of soybean aphid, of which, 4.3% were coccinellids. In general we observed a coccinellid community dominated by native species (Brachiacantha decempustulata, Brachiacantha ursina, Colleomegilla maculatta, Cycloneda munda, Diomus sp., Hippodamia convergens, Hippodamia parenthesis, Hyperaspis sp., and Microweisea sp.) with few if any invasives (Coccinella septempunctata and Harmonia axyridis). This is in sharp contrast to Iowa soybean fields were invasive coccinellids dominate. We will discuss the impact of prairie restoration on the aphidophagous community and to what extent these habitats may improve the biological control of soybean aphids.

Species 1: Hemiptera Aphididae Aphis glycines (soybean aphid)
Species 2: Coleoptera Coccinellidae