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Title: The effects of crop intensification on the diversity of native pollinator communities

item Mogren, Christina
item Rand, Tatyana
item FAUSTI, SCOTT - South Dakota State University
item Lundgren, Jonathan

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2016
Publication Date: 6/6/2016
Publication URL:
Citation: Mogren, C.L., Rand, T.A., Lundgren, J.G. 2016. The effects of crop intensification on the diversity of native pollinator communities. Environmental Entomology, 45(4), 865–872. doi: 10.1093/ee/nvw066.

Interpretive Summary: As cropping intensity throughout the U.S. increases, habitat for beneficial species becomes limiting. Pollinator communities face numerous challenges in the U.S., including habitat losses. We examined how landscape changes affect the constituency of native pollinator communities in eastern South Dakota. As cropland increases in the landscape (within a 3 km radius), local pollinator communities become more abundant, but less even; they come to be dominated by a few agriculturally adapted species. Predominant bees in our system were Lasioglossum spp. and Mellisodes spp.; hoverflies and wasps were other abundant pollinator groups. Surprisingly, local vegetation communities had few effects on pollinator community structure. This data illustrates the importance of landscape structure and non-crop habitat in conserving native pollinator communities.

Technical Abstract: Recent increases in agricultural conversion are leading to a decline in native grasslands and natural resources critical for beneficial insects. However, little is known regarding how these regional changes are affecting pollinator diversity. Insect pollinators were collected at 12 locations in Brookings Co., SD. Using the 2013 USDA Cropland Data Layer, land use types were categorized within a 3 km radius around the sampling locations. The proportion of the sampling regions dedicated to crops, managed perennial habitat, and uncropped areas were regressed against pollinator species richness, evenness, and abundance. Corn, soybean, and grass/pasture together accounted for 75% of the landscape. The most abundant pollinator species were Melissodes agilis and M. trinodis (Hymenoptera: Apidae), Lasioglossum pruinosum (Halictidae), and Toxomerus marginatus (Diptera: Syrphidae). As corn increased in the landscape, so did the abundance of Melissodes, halictids, syrphids, and wasps, with an accompanying decrease in species evenness. Alfalfa increased species richness and abundance of bees and wasps, and increased syrphid species evenness. Cumulatively, cropped areas increased the abundance of bees and syrphids, while managed perennial areas decreased evenness and richness. Local vegetation during the sample period had no effect on pollinator diversity. Across pollinator groups in the study region, there was a negative relationship between abundance and evenness, suggesting selection for a few dominant species within this highly developed agricultural landscape. Incorporating more floral resources at the farm level throughout the region is likely to enhance pollinator diversity by providing critical habitat and forage and lessen the negative effects of large monocultures.