Population densities of corn flea beetle (Coleoptera: Chrysomelidae) and incidence of Stewart's wilt in sweet corn.
To quantify populations of the corn flea beetle, Chaetocnema pulicaria Melsheimer (Coleoptera: Chrysomelidae), and refine estimates of a threshold for its control to prevent Stewart's wilt caused by Erwinia stewartii, sequential plantings of 'Jubilee' sweet corn were made at 2-wk intervals from April or May through August or September 2001 and 2002 at four locations from southern to northern Illinois: Simpson, Brownstown, Champaign, and Mendota. Densities of C. pulicaria and incidence of Stewart's wilt were monitored weekly. At Mendota, where C. pulicaria populations were decimated by cold temperatures during winter 2000-2001, densities reached 33.3 beetles per 15-cm yellow sticky trap per day by September 2002, after a mild 2001-2002 winter. Maximum incidence of Stewart's wilt in single plots at Simpson, Brownstown, Champaign, and Mendota was 22, 36, 39, and 2%, respectively, in 2001, and 33, 47, 99, and 87%, respectively, in 2002. In 24 plots where beetle densities were < or =2 per trap per day, Stewart's wilt incidence was <5% in 20 plots. We propose that two corn flea beetles per trap per day be used as a threshold for insecticide application to seedlings to control C. pulicaria and minimize subsequent incidence of Stewart's wilt in processing sweet corn. Enzyme-linked immunosorbent assays indicated that E. stewartii incidence in C. pulicaria peaked at 67, 62, and 54%, respectively, at Simpson, Brownstown, and Champaign, in 2001, and at 71, 76, and 60%, respectively, in 2002. Further studies might allow the use of areawide or field-specific estimates of E. stewartii incidence in corn flea beetles for adjusting management decisions.
Cook
K A
KA
University of Illinois, Department of Crop Sciences, 1102 S. Goodwin Ave., Urbana, IL 61801, USA.
Weinzierl
R A
RA
Pataky
J K
JK
Esker
P D
PD
Nutter
F W
FW
D000818:Animals; D001517:Coleoptera / Q000382:microbiology*; D004885:Erwinia; D007087:Illinois; D007303:Insect Vectors; D007306:Insecticides / Q000008:administration & dosage; D010935:Plant Diseases / Q000382:microbiology*; D011156:Population Density; D012621:Seasons; D003313:Zea mays / Q000382:microbiology* / Q000469:parasitology
D007306:Insecticides