Plant Diversity and Its Effects on Populations of Cucumber Beetles and Their Natural Enemies in a Cucurbit Agroecosystem

• Published in: HortScience Vol. 32; no. 3; p. 511
• Main Authors: Walker, Jason, Caldwell, John S, Jones, Robert H
• Format: Journal Article
• Language: English
• Published: 01.06.1997
• ISSN: 0018-5345; 2327-9834
• DOI: 10.21273/HORTSCI.32.3.511B

To assess the value of uncultivated vegetation for control of cucumber beetles, populations of striped ( Acalymma vittatum Fabr.), spotted ( Diabrotica undecimpunctata howardi Barber), and western cucumber beetles ( Acalymma trivittatum Mann.) (Coleoptera: Chrysomelidae) and natural enemy Diptera flies (as an indicator of Celatoria spp. parasitoids), Pennsylvania leatherwings (Chauliognathus pennsylvanicus DeGeer) (Coleoptera: Cantharidae), lady beetles (Coleoptera: Coccinellidae), Hymenoptera wasps, and spiders were monitored with sticky traps on 50-m transects running through a field of Cucumis sativa L. `Arkansas Littleleaf' into bordering uncultivated vegetation. Plant species composition was determined in square plots around each sticky trap by estimating total plant cover and height distribution of plants from 0 to 1.0 m. In both years, numbers of cucumber beetles increased and numbers of Diptera decreased towards the crop. These trends increased monthly to peaks in Aug. 1995 (0.3 to 6.0 striped cucumber beetles; 40.0 to 15.3 Diptera) and July in 1996 (0.1 to 7.1 striped cucumber beetles; 46.7 to 15.5 Diptera). Abundance of individual plant species contributed more to maximum R 2 regression of insect populations than did measures of plant diversity in sampling squares. Diptera were negatively correlated with sweet-vernal grass (r = –0.65 at 0 m) and wild rose ( r = –0.62 at 0.5 m) in 1995, and goldenrod ( r = –0.31, –0.59, and –0.53 at 0.5, 0.75, and 1.0 m, respectively) in 1996, but positively correlated with wild violets ( Viola spp.) ( r = +0.38 at 0 m) in 1996. Cucumber beetles were negatively correlated with wild violets ( r = –0.30 at 0 m) and white clover ( Trifolium repens ) ( r = –0.37 at 0 m) in 1996. These results suggest that increasing or decreasing specific plants in uncultivated vegetation might be useful for influencing pest and beneficial insect populations in cucurbit production.