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Title: Effects of relay-intercropping sorghum with winter wheat, alfalfa, and cotton on lady beetle (Coleoptera: Coccinellidae) abundance and species composition

Author
item PHOOFOLO, MPHO - National University Of Lesotho
item GILES, KRISTOPHER - Oklahoma State University
item Elliott, Norman - Norm

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2010
Publication Date: 7/15/2010
Citation: Phoofolo, M.W., Giles, K.L., Elliott, N.C. 2010. Effects of relay-intercropping sorghum with winter wheat, alfalfa, and cotton on lady beetle (Coleoptera: Coccinellidae) abundance and species composition. Environmental Entomology. 39(3):763-774.

Interpretive Summary: Creating conditions that enhance the abundance of resident populations of natural enemies in agroecosystems is considered critical to the efficiency of biological control of insect pests. We conducted a study to determine the potential of relay intercropping for enhancing the abundance of aphidophagous lady beetles in sorghum. The purpose of relay intercropping is to provide a sequence of crops in close proximity throughout the year so that natural enemies can move from crop to crop and remain in the field to combat pests. A relay intercropping system consisting of alfalfa, winter wheat, and cotton as intercrops and sorghum as a main crop was compared with sorghum monoculture plots at two study sites in Oklahoma from 2003-2006. There were no differences in the number of lady beetles or aphids between soghum grown in relay a relay intercropping system or a monoculture. Our results provide no evidence to suggest that relay intercropping provides any advantage over sorghum monoculture for pest management of greenbugs in grain sorghum.

Technical Abstract: Creating conditions that enhance the abundance of resident populations of natural enemies in agroecosystems is considered critical to the efficiency of biological control of insect pests. We conducted a study to determine the potential of relay intercropping for enhancing the abundance of aphidophagous lady beetles in sorghum. A relay-intercropping system consisting of alfalfa, winter wheat, and cotton as intercrops and sorghum as a main crop was compared with sorghum monoculture plots at two study sites in Oklahoma from 2003-2006. Lady beetles and aphids were sampled throughout the season using sticky traps and field counts on individual sorghum plants. Results from sticky traps and field counts show that differences in abundance and species composition of lady beetles between intercropped and monoculture sorghum were not statistically different during each year of study. Also, the lady beetle-greenbug ratios in relay intercropped and monoculture plots were not significantly different. Lack of significant effects of relay-intercropping in our study may have been attributable to the confounding effects of spatial and temporal scale as well as low number of aphids and other alternative prey in the intercrops compared to high incidence of corn leaf aphids in sorghum early in the season.