Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2008
Publication Date: 1/12/2009
Citation: Rajewski, J.A., Ni, X., Wilson, J.P., Dweikat, I., Buntin, G.D. 2009. Evaluation of resistance to chinch bug in pearl millet in temperate and subtropical environments. Online. Plant Health Progress doi:10.1094/PHP-2009-0112-01-RS.
Interpretive Summary: Chinch bug is the most important insect pest for pearl millet forage and grain production in the Southeast, Midwest, and Midsouth regions of the U.S. All resistance evaluations to date have been conducted on a limited, local scale. This is the first evaluation of chinch bug resistance under both temperate and subtropical climate conditions. All pearl millets expressed some damage from chinch bug feeding. Differences in resistance were expressed as a slower rate of the development of plant damage. Repeated assessments of plant damage over time are necessary to identify germplasms with resistance. Expression of resistance in several hybrids tended to be dominant or overdominant in expression. An agronomically desirable but susceptible inbred might be commercially useful if crossed to an inbred that has a dominant expression of resistance. Some region-specific responses to chinch bug feeding were observed, due either to environment or perhaps genetic differences in the insect populations between the two locations. Evaluations at multiple locations are needed to identify widely effective resistance to chinch bug in pearl millet.
Technical Abstract: Pearl millet [Pennisetum glaucum (L.) R. Br.] inbreds and hybrids were evaluated for resistance to chinch bug [Blissus leucopterus leucopterus (Say)] at Lincoln, NE and Tifton, GA in 2003 and 2004. Plant damage from insect feeding was assessed throughout the growing season. Differences plant mortality, stunting, leaf sheath necrosis, and tiller mortality were observed over time. Resistance was expressed quantitatively by a slower rate of plant damage to resistant genotypes compared to susceptible ones. Across trials, inbreds 59464B and 59668M-1 were most frequently identified as resistant. Tift 99B was identified as a susceptible inbred in every trial and by every assessment criterion. Evidence for region-specific resistance caused either by environmental conditions or genetic differences in the insect populations between the two locations was observed. Inbreds 03GH707 and Tift 454, developed at Tifton, were classified as resistant only in some of the assessments at Tifton, but not at Lincoln. 16RmR1, developed at Lincoln, was identified as susceptible in both Lincoln experiments, but not at Tifton. 03GH706 susceptible in some of the Tifton assessments, but was not among the most susceptible inbreds in the Lincoln experiments. When insect damage among the hybrids made with Tift 454 was compared, resistance tended to be dominant or overdominant in expression. Evaluations are needed at multiple locations to more effectively identify resistance to damage caused by chinch bug feeding in pearl millet.