Cool-season cover crops relay intercropped with cantaloupe: Influence on a generalist predator Geocoris punctipes (Hemiptera: Lygaeidae).
Bugg, Robert L., Felix L. Wackers, Kathryn E. Brunson, James D. Dutcher and Sharad C. Phatak

J. Economic Entomology 84:408-416. 1991

Reviewer's Note: Several species of bigeyed bugs (Geocoris spp.) are important generalist predators in California field and row crops; these bugs attack a wide array of pests and are believed important in preventing outbreaks of aphids and various species of Lepidoptera. Geocoris punctipes, the subject of this paper, is abundant in much of California, Arizona, and the southeastern U.S. If, as this study suggests, cover crops can be used to improve performance of these and other generalist predators, this could have important implications for pest management.

In southern Georgia, fall-seeded cool-season cover crops were used in efforts to enhance densities of entomophagous insects on relay-intercropped spring plantings of cantaloupe. Eight cover-cropping regimes, including 'Mt. Barker' subterranean clover (Trifolium subterraneum) 'Vantage' vetch (Vicia sativa X Vicia cordata), 'Chilean 78' common lentil (Lens culinaris), 'Dixie' crimson clover (Trifolium incarnatum), 'Wrens Abruzzi' cereal rye (Secale cereale), 'Florida Broadleaf' mustard (Brassica hirta), a six-way polyculture of the crops just mentioned (which was dominated by cereal rye), and a weedy fallow control, were tested in a replicated trial. Cover crop significantly affected densities of the predominant predator, a bigeyed bug, Geocoris punctipes, amid cover crops (P=0.000l); on or near cantaloupe plants (P= 0.0001); and on or near sentinel egg masses of fall armyworm, Spodoptera frugiperda pinned to cantaloupe leaves (P=0.0487). Thirteen types of predatory arthropod were found feeding on these egg masses. No significant difference was found for proportions of egg masses occupied or damaged by predators, but this non-significance was marginal (P = 0.0637). For all measurements of predator abundance and efficiency, absolute responses were highest for the plots of subterranean clover. Numbers of bigeyed bugs per sentinel egg mass were significantly greater for the subterranean clover regime than for cereal rye, crimson clover, and a polyculture of six cover crops, but were not significantly greater than for 'Vantage' vetch or the weedy fallow control plots. Rye showed particularly low densities of bigeyed bugs. Cover crops had no apparent effect on densities of aphids or whiteflies on cantaloupe leaves, but densities of these pests were uniformly low through-out the study.

For more information write to: Information Group, UC Sustainable Agriculture Research and Education Program, University of California, Davis, CA 95616.

(DEC.331) Contributed by Robert Bugg