Both Nilaparvata lugens Stål and Laodelphax striatellus Fallén has been known as the major rice pests which were irregularly migrated into Korea by wind current from China. We re-arranged and compared the resistance profiles to detect the existence convergent adaptation by using the previously published dataset (N. lugens at 2014, 17:711-716 and L. Striatellus at 2016, 19:247-252 in J. Asia Pac. Entomol., respectively). Both species commonly exhibited the high level of resistance to imidacloprids. Especially, the immigrant populations of L. Striatellus exhibited higher resistance level to indigenous populations, suggesting that they would settle down in Korea with insecticide resistance traits being predisposed. To detect the convergent adaptation to insecticide, pearson correlation analysis were employed by comparing mean dosage of LD50 and resistance ratio to nine insecticides. Strikingly, high and similar dosage responses were observed between the two species with high correlation coefficients of 0.928 (df=7, P <0.001) and 0.950 (df=7, P <0.001), respectively, in the comparison of LD50 vs. resistance ratio. This finding indicates that convergent adaption has occurred in both species through consistent selection by insecticides with similar usage patterns.

The brown planthopper (BPH), Nilaparvata lugens (Stål), is an important pest in rice paddies. Because BPH cannot survive under low temperature conditions (<12℃), its outbreak in temperature areas depends on migration from overwintering areas of BPH. Geospatial distribution of BPH overwinterng area would be changed under future climate. The objective of the present study was to assess potential areas for BPH overwintering in Asia under current and future climate conditions. To reduce model uncertainty, we explored an ensemble modeling approach using five species distribution models (SDMs) and climate data from five general circulation models (GCMs). For future projections, outputs from an SDM with five sets of GCM data were averaged into a single map. Then, five maps from individual SDMs were summarized to assess the potential overwintering areas of BPH. Overall, the BPH overwintering areas expanded northward under future climate conditions. The degree of expansion in overwintering areas differed by region. For example, the uppermost boundary of BPH overwintering areas shifted north about 150 Km in southern China by 2050s. In Japan, small areas in the southern Kyushu were projected as potential areas of BPH overwintering. These results indicated that migration of BPH into East Asia including northern China, Korea, as well as Japan would occur early in the growing season, which could result in considerable damages in rice production.