BREEDING RESISTANT SUGARCANE FOR MANAGING THE STEM BORER DIATRAEA SACCHARALIS: PROGRESS AND PROSPECTS FOR LOUISIANA

THE STEM borer, Diatraea saccharalis (F.), is an important insect pest of sugarcane in Louisiana. Growing resistant varieties is a component of the Integrated Pest Management Program as practised in Louisiana for managing this insect; however, the release of stem borer resistant varieties has been intermittent. In 1986, researchers at the USDA, Agricultural Research Service (ARS) and LSU Agricultural Center – the two breeding programs in Louisiana – initiated an effort to increase stem borer resistance without encumbering the Louisiana sugarcane variety program (LSVP) with an additional selection trait. In this approach, clones with high levels of stem borer resistance are developed at the USDA, ARS in Houma via a recurrent selection program for borer resistance (RSB) and these resistant clones are used as parents in crossing. Advancement data from the Louisiana State University AgCenter’s sugarcane breeding program were evaluated to determine our success in incorporating the new resistant germplasm into the progeny advancing through this program. A statistical test using the cumulative logit model showed non-significant difference (P > 0.05) in advancement rates of clones between the RSB and non-RSB families. However, because of fewer seedlings derived from crosses with at least one RSB parent, very few clones were given permanent variety assignments from the RSB population; only seven in the 1991 to 2002 series. A simulation study was done to determine the effect of increasing selection rates on recovery of RSB clones at the different stages of the breeding program. The cumulative logit model showed that increasing selection rates from Stage I to Stage II will result in a significant increase in the number of RSB clones assigned a variety designation. From this study we propose that the number of resistant crosses be increased and the selection rate of RSB crosses at Stage I be doubled to 13%.