Biological reaction of migrated the brown planthopper, Nilaparvata lugens Stål, on resistant rice varieties in Korea

The brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae), is a major insect pest of rice in Korea. It has been presumed that BPH migrate annually from the southeastern part of China along the southwesterly airflow into Korea from approximately mid-June to late July, the rice planting season. The migrant BPHs have three or four generations per year and occasionally cause serious damage (hopperburn) to rice plant by direct feeding. Host plant resistance has been emphasized as a major tactic in integrated pest management because of its economic and environment-friendly advantages. Use of resistant varieties can reduce of pest damage, increase in the effect of pesticides, decrease a virus disease mediated by Brown planthopper and eliminate the various side effects from the chemical control.

 This study lays the foundation for future work on rice breeding for BPH resistance and we observed biological reaction such as fecundity, life cycle, growth period and survival rates to investigate correlation between adaptation of BPH populations and BPH-resistant rice varieties according to duration. We used the 6 varieties of rice, susceptible Ilpumbyeo and resistant genes of Samgangbyeo (Bph1), Mudgo (Bph1), M63 (Bph2), ASD7 (Bph2) and Gayabyeo (Bph1+α). Experiments were carried out with 5 BPH groups collected over a period of several years; 1980, 2005, 2007, 2012 and 2013, respectively. The BPHs and rice seedlings were maintained at 25±2°C, 60±5% RH and 15L:9D photoperiod in the insectary.

 By comparison with the number of nymphs hatched among cultivars, the fecundity of 1980s-BPH was markedly less than other BPH groups in BPH-resistant rice cultivar. As time goes by, showed a tendency to increase the more fecundity. Looking at life and growth period, 1980s-BPH populations inoculated with two resistant varieties rice (samgangbyeo and M63) didn’t adapt to rice so that life and nymphs period is a very short, but 2005-BPH, 2007-BPH, 2012-BPH populations showed a normal growth period. In the survey survival rates of BPH populations, survival rates of 1980s-BPH was the lowest but flying recently populations tended to the higher generally. When the population of 1980s-BPH compared with population of 2013-BPH, it was investigated that the survival rates has increased up to minimum 6%(Mudgo) and maximum 70%(Samgangbyeo).

 This study provides a meaningful association with the interaction between rice and the BPH. Because recently collected BPH populations adapted to resistant rice varieties, they caused serious damage to the rice and its resistance-breaking ability were increased. From the above, it is apparent that we should careful about outbreak of BPH in the future.