THE GENETIC-BASIS OF HOST-PLANT ADAPTATION IN THE BROWN PLANTHOPPER (NILAPARVATA-LUGENS)

We studied the genetic architecture of host plant adaptation in two po pulations of brown planthopper Nilaparvata lugens (Homoptera: Delphaci dae): one feeding on cultivated rice Oryza sativa and the other feedin g on a weed grass Leersia hexandra. Proportional weight change, surviv al and development time of inbred Leersia- and rice-feeding lines, F-1 , F-2, and backcross classes have been examined. Most of the performan ce differences among populations seem to be controlled by a few genes. Dominance of rice population alleles over Leersia population alleles was quite strong, and there was evidence for epistatic interaction. Ny mph-to-adult survival of the cross classes was found to be highly corr elated with mean weight change of the adults. These results are discus sed in relation to a presumed host shift from Leersia to rice.