False indigo (Amorpha fruticosa L.) is a native North American leguminous shrub frequently found on shores of lakes and banks of rivers and streams in eastern and central United States and is present in 46 of the 48 contiguous states. It is planted for wildlife habitat, streambank erosion control, and ornamental purposes. Over several years, 16 collections of mature pods of false indigo were obtained from shorelines of four lakes and one cultivated planting in the northern Great Plains to determine frequency of pod predation by bruchid beetles. Frequency of pod predation by Acanthoscelides submuticus (Sharp) varied significantly among locations, among years, and among plants within locations. Out of a total of 5,000 pods examined from 15 different collections, 41% were infested by A. submuticus. Acanthoscelides pallidipennis (Motschoulsky) occurred in only one of the 16 collections, but it infested 60% of those pods. The range in pod predation frequencies for A. submuticus ranged from 70% for a collection at Oakwood Lake, South Dakota, to 7% for a collection from a cultivated planting at Bismarck, North Dakota. The parasitoids Dinarmus acutus Thomson and Lyrcus incertus (Ashmead) were reared from pods infested with A. submuticus. Acanthoscelides submuticus is a new host record for D. acutus. Although pod predation by A. submuticus showed considerable spatial and temporal variation, it ultimately resulted in a significant loss of viable seed production in three natural populations of false indigo along shorelines of lakes in the northern Great Plains.
Proceedings of the South Dakota Academy of Science
Boe, Arvid and Johnson, Paul J., "Seed Predation by Acanthoscelides Submuticus and A. Pallidipennis (Coleoptera: Bruchidae) in False Indigo in the Northern Great Plains" (2008). Native Plant Focused Publications. 24.