Feeding patterns of Scirpophaga incertulas (Lepidoptera: Crambidae) on wild and cultivated rice during the booting stage

Abstract

Rice plants are vulnerable to the yellow stem borer, Scirpophaga incertulas (Walker), during the booting phase, when infestations cause the greatest yield loss. Although the moth is ubiquitous in rice-growing regions, S. incertulas feeding patterns on booting plants have been poorly characterized. We studied the early-instar feeding patterns of S. incertulas on wild and cultivated rice accessions to determine where larvae feed and if feeding route influences larval survival and development. Three cultivated (Taichung Native 1, IR64, and IR72) and three wild rice accessions (two accessions of Oryza nivara and one accession of O. rufipogon) were chosen for the study. Larvae were introduced onto booting plants and sampled after 6 h, 1 d, 2 d, 4 d, and 7 d. Approximately 25% more larvae survived on cultivated accessions than on wild accessions. Larvae were also 15% more likely to feed on the panicle of cultivated accessions than wild accessions, and panicle-feeding improved larval survival and development. Stem borer feeding route depended on plant phenology; larvae were more likely to feed on the panicle than on vegetative structures on booting, heading, and flowering tillers. Because all stems were cut by the seventh day if larvae fed on the panicle, resistance during the booting phase may be effective if it reduces the likelihood of panicle feeding or if strong antibiotic resistance can be found in the panicle. © 2006 Entomological Society of America.