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United States Department of Agriculture

Agricultural Research Service

Title: Combining Ability of Resistance Leads and Identification of a New Resistance Source for Western Corn Rootworm (Coleoptera: Chrysomelidae) Larvae in Corn

Authors
item HIBBARD, BRUCE
item Darrah, Larry
item Barry, B

Submitted to: Maydica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 1999
Publication Date: N/A

Interpretive Summary: The western corn rootworm is a major insect pest in continuous corn, but no viable alternatives to insecticides are available for its control. From 1994 to 1996, seven germplasm sources of corn with reduced corn rootworm damage were identified. Use of these resistance sources will likely require crossing them into elite, proprietary germplasm. To determine which of our germplasm sources had the best potential for contributing cor rootworm resistance to their progeny, each parental line was crossed with each of the other six lines and two susceptible cultivars and evaluated at three central Missouri locations in 1997. Ten of the best crosses in the diallel from 1997 were self pollinated in a 1997-1998 winter nursery and seed from each cross were evaluated along with checks in 1998. Feeding damage was evaluated using a rating scale (1 = resistant, 6 = susceptible) when approximately half of the larvae had stopped feeding and pupated. One ecross was the best of all entries evaluated in 1997 and 1998, had significantly less damage than the resistant check both years, and represents a new source of native resistance to feeding damage caused by corn rootworm larvae. Three of the parents contributed corn rootworm resistance to their respective progeny as indicated by significant, negative general combining ability effects. The significant general combining ability effects found and lack of significant specific combining ability effects in the crosses suggest that when these three lines are crossed to a series of other parents, the progeny can be expected to have lower levels of corn rootworm damage.

Technical Abstract: The western corn rootworm is a major insect pest in continuous corn, but no viable alternatives to insecticides are available for its control. From 1994 to 1996, seven germplasm sources of corn with reduced corn rootworm damage were identified. Since utilization of these sources would likely require backcrossing into elite germplasm, a diallel including the seven resistance lines and inbred lines B37 and Mo47 was formed to determine which had the best potential for contributing corn rootworm resistance to progeny. Each parental line was crossed reciprocally with each of the other eight. Parental germplasm, available crosses, and resistant and susceptible checks were evaluated at three central-Missouri locations in 1997. Ten of the best crosses in the diallel from 1997 were selfed in a 1997-1998 winter nursery and seed from three ears for each cross (30 ears total) were evaluated along with checks in 1998. Although damage to the susceptible check was less than desired in 1997, 29 of the 34 crosses evaluated (combining reciprocal crosses) were significantly less damaged than the susceptible check and two were significantly less damaged than the resistant check. As indicated by a significantly, negative general combining ability effect, three of the parents contributed corn rootworm resistance to their respective progeny. Specific combining ability effects for these crosses were not significant. In 1998, one entry had significantly less damage than all other entries. The entry TL92A PAR 1779 60-4 NGSDCRW1(S2)C4-15-2S2 was the best of all entries evaluated in 1997 and 1998, had significantly less damage than the resistant check both years, and represents a new source of native resistance to feeding damage caused by corn rootworm larvae.

Last Modified: 8/19/2014
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