|El Khishen, Ahmed|
|French, Bryan - Wade|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2009
Publication Date: 12/1/2009
Citation: El Khisen, A.A., M.O. Bohn, D.A. Prischmann-Voldseth, K.E. Dashiell, B.W. French and B.E. Hibbard. 2009. Native Resistance to Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Feeding: Characterization and Mechanisms. Journal of Economic Entomology. 102(6): 2350-2359. Interpretive Summary: The western corn rootworm (WCR) is a major insect pest in continuous corn production. By feeding on corn roots, WCR causes economic losses due to plant lodging and decreased nutrient uptake. Currently, insecticides and transgenic corn are the only available options for its control under continuous corn production. Seven maize genotypes previously known for native resistance to WCR larval feeding were evaluated along with two susceptible lines and transgenic resistant control in the field for plant damage, WCR recovery, and root characteristics. WCR larvae recovered were further analyzed for size. In general, the genotypes selected for evaluation because of their previously documented resistance to WCR larval feeding had less damage, fewer WCR recovered, smaller WCR recovered, and fewer adults recovered than the susceptible controls. One of these genotypes, SUM2162, was significantly less damaged than all other native sources of resistance. WCR recovered from SUM2162 and SUM2068 were significantly smaller than larvae recovered from all other maize lines, indicating a specific mechanism of resistance. The seven genogypes offers sources of native resistance to WCR larval feeding for transfer of desired resistance genes into high yielding commercial varieties.
Technical Abstract: Seven maize, Zea mays L., genotypes previously known for native resistance to western corn rootworm, Diabrotica virgifera virgifera LeConte, larval feeding (SUM2068, SUM2162, CRW3(S1)C6, NSS1×CRW3(S1)C6, PI583927, CRW2(C5), and AR17056_16) were evaluated along with three control maize genotypes in the field for plant damage, larval recovery, adult emergence, root size, and root regrowth. Larvae recovered were further analyzed for head capsule width and dry weight and adults for dry weight. All factors evaluated with the exception of adult dry weight varied significantly among maize genotypes. Control genotypes included a highly susceptible hybrid, B37×H84, a transgenic rootworm-resistant hybrid expressing the modified Cry3A protein (MIR604), and the untransformed modern hybrid with the same genetic background as the MIR604 we used (isoline) as a second susceptible control. In general, the genotypes selected for evaluation because of their previously documented resistance to western corn rootworm larval feeding had less damage, fewer larvae recovered, smaller larvae recovered, and fewer adults recovered than the susceptible controls. SUM2162 was significantly less damaged than all other native sources of resistance. Western corn rootworm larvae recovered from SUM2162 and SUM2068 were significantly smaller in terms of head capsule width and average weight than larvae recovered from all other maize genotypes, indicating that antibiosis is a mechanism of resistance for these two hybrids.