Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2008
Publication Date: June 15, 2008
Citation: Behle, R.W., Hibbard, B.E., Cermak, S.C., Isbell, T.A. 2008. Examining cuphea as a potential host for western corn rootworm (Coleoptera: Chrysomelidae): larval development. Journal of Economic Entomology. 101(3):797-800. Technical Abstract: In previous crop rotation research, adult emergence traps placed in plots planted to Cuphea PSR-23 (a selected cross of C. viscossisma and C. lanceolata) caught high numbers of adult western corn rootworms, Diabrotica virgifera virgifera LeConte, suggesting that larvae may have completed development on this broadleaf plant. Because of this observation, a series of greenhouse and field experiments were conducted to test the hypothesis that Cuphea could serve as a host for larval development. Two experiments that infested greenhouse grown plants with neonates of a colonized non-diapausing strain of the beetle showed no survival of larvae on Cuphea, though larvae did survive on the positive control (corn, Zea maize) and negative control (sorghum, Sorghum bicolor) plants. To evaluate native insects, soil samples were collected from the field used for previous corn: Cuphea rotation research, placed in pots, and planted to corn and Cuphea in the greenhouse. Dissecting the soil for rootworm larvae failed to find larvae in pots planted to Cuphea compared with more than two rootworms per pot for those planted to corn. Also, soil samples collected June 20, July 7, and July 29, 2005, from field plots planted to Cuphea did not contain rootworm larvae compared with means of 1.28, 0.22, and 0.00 rootworms kg-1 soil, respectively, for samples collected from plots planted to corn. Emergence traps captured a peak of 8 beetles trap-1 day-1 from corn plots on July 8 compared with a peak of 0.5 beetles trap-1 day-1 on August 4 from Cuphea plots. Even though a few adult beetles were captured in the emergence traps placed in the Cuphea plots, it is not believed to be the result of successful larval development on Cuphea roots. All the direct evidence reported here supports the conventional belief that rootworm larvae do not survive on broadleaf plants, including Cuphea.