![]() In its place, field crops-mainly corn, soybeans, alfalfa, and small grains such as wheat and oats-have become a major component of the landscape ( Dumke and Dobbs, 1999 Rashford et al., 2011 Wright and Wimberly, 2013).Įach of the field crops in eastern South Dakota is colonized annually by its own complex of arthropod pests that includes aphids, defoliators, and stem borers ( Bing et al., 1999 Hesler et al., 2000, 2005, 2018 Hutchinson et al., 2010 Lundgren et al., 2013 Supplementary Table 1). Less than 14% of tallgrass prairie remains in North America ( Samson et al., 2004). Possible explanations and implications for observed patterns in coccinellid diversity and individual species abundances in field crops and restored prairie of eastern South Dakota are discussed with respect to prey, agronomic trends, and landscape factors.Įastern South Dakota, USA, was historically part of the tallgrass prairie portion of the North American Great Plains before conversion of a large majority of land to agriculture in the mid-1800s ( Maizel et al., 1998). Sample rates of coccinellids in alfalfa, spring grains, and corn in this study were 74, 26, and 6%, respectively, compared to that of a previous study from the region, further indicating substantial decreases in coccinellid abundance. As a group, native adult coccinellids showed a significant declining trend in corn but not in other habitats, whereas trends for non-native adult coccinellids were non-significant in all habitats. Annual abundance of coccinellids varied considerably within habitats, but declining trends were evident from significant negative regressions in annual abundance for adult and immature coccinellids in corn and adults in soybean. ![]() ![]() Coccinellid assemblages were similar for alfalfa and winter wheat, but not for other habitats, which possessed distinct coccinellid assemblages based on rank abundance. However, coccinellid species ranged considerably in their evenness of habitat use, resulting in differences in rank abundance among habitats. The seven most abundant species constituted 99% of all coccinellids sampled and were recorded from all six habitats. axyridis) were the third- and fourth-most abundant species, respectively. In all, 17,338 aphidophagous coccinellids comprising 10 species were sampled. ![]() This paper summarizes long-term results from 14 years (2007–2020) of sampling coccinellids by sweepnet and timed searches in five field crops and restored prairie in eastern South Dakota. Since then, two other non-native coccinellids ( Harmonia axyridis and Hippodamia variegata) have established in eastern South Dakota, but long-term analysis of their impact on the aphidophagous coccinellid guild is lacking. In particular, populations of three native species declined drastically ( Coccinella transversoguttata richardsoni) or effectively disappeared ( Coccinella novemnotata, Adalia bipunctata) from agricultural landscapes in eastern South Dakota, U.S.A., following establishment of an invasive coccinellid ( Coccinella septempunctata) in the 1980s. Several native coccinellids in North America have declined in association with the introduction of invasive species of lady beetles. Lady (= ladybird) beetles (Coleoptera: Coccinellidae) provide agroecosystem services as major predators of aphids and other pests of field crops. Department of Agriculture, Brookings, SD, United States North Central Agricultural Research Laboratory, U.S.
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