Mechanisms of resistance in maize to western corn rootworm
1997
Arnason, J.T. | Larsen, J. | Assabgui, R. | Xie, Y. | Atkinson, J. | Philogene, B.J.R. | Hamilton, R.I.
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is considered a primary pest threatening maize cultivation in North America. Branson et al. (1983) indicated the existence of an unidentified antibiosis factor in resistant germplasm from South Dakota, in addition to the well known tolerance. Our laboratory has identified the hydroxamic acids (Hx): DIMBOA, DIM2BOA, HMBOA and MBOA as antibiosis factors in maize roots. These substances induce larval mortality and delay development of the insect. Behavioral data suggest that Hx also reduce acceptability of maize roots as hosts. Using high pressure liquid chromatography (HPLC), these biochemicals have been located in maize tissue at the rootworm feeding sites. A greenhouse study demonstrated that maize varieties with high Hx content were less damaged than varieties with low Hx content when artificially infested with WCR larvae. This result has been confirmed in the field with 7 inbreds of varying Hx content which were artificially infested with WCR eggs. Pre- screening methods for selection of genotypes based on Hx content are currently being evaluated. Chromosome mapping of resistance and phytochemistry is also being undertaken.
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