Nilaparvata lugens Stål is one of the important migratory pests of rice paddy fields in Korea. Resistance levels to nine insecticides were monitored in 12 local strains and correlation analysis was conducted to determine cross-resistance relationships among the tested insecticides. The local strains revealed 1.3- to 28.0-, 1.6- to 6.0-, 2.8- to 237.0-, 0.6- to 0.9-, and 0.7- to 1.3-fold resistance to carbamates, organophosphates, neonicotinoids, fipronil and etofenprox, respectively. Organophosphates revealed moderate correlations with benzofuranyl methylcarbamate (r = 0.566 - 0.614, p > 0.01). Three neonicotinoids were not correlated each other, but imidacloprid and clothianidin were moderately correlated with several benzofuranyl methylcarbamate and organophosphate insecticides (r = 0.590 - 0.705, p > 0.05), indicating that unknown common factors (such as detoxification enzymes) might contribute to resistance to both insecticides. Fipronil and etofenprox exhibited low levels of resistance and cross-resistance with other insecticides, suggesting their potential as an effective insecticide for field application. Resistance level monitoring and correlation analysis would be valuable for the selection of appropriate insecticides to control insecticide-resistant N. lugenes, a typical migratory pest in Korea.

We developed and characterized five polymorphic microsatellites of Nilaparvata lugens from hybridization method using biotin enrichment strategy and two polymorphic microsatellites from Next Generation Sequencing. Also 11 microsatellites that developed by Sun et al. (2011) are employed to carry out genetic analysis of N. lugens in Southeast Asia. The number of alleles per locus ranged from 2 to 12 with an average of 4.63 alleles per locus. The mean observed heterozygosity of the eleven populations ranged from 0.031 to 0.938 and the expected hetetrozygosity ranged from 0.031 to 0.881. Signifiant genetic differentiation was detected among the three N. lugens populations as the FST ranged from 0.028 (Cheong Do and Ha Long) to 0.161 (CH and BN). The results of microsatellite marker suggested that found N. lugens migrated to Korea at least two times in different period or once. Genetic distance of N. lugens between Korea and Hi Pong were mostly closed and genetic distance of Ha Long and HCM were relatively closed. In this study, development of microsatellites should facilitate the study of future population genetics of N. lugens, and eventually elucidate the route of N. lugens migration to Korea. Thus, combining satisfactory microsatellite markers and intensive surveillance methods in paddy field could be easy to understand to the N. lugens migration mechanism.