Occurrence and short-distance migration of Nilaparvata lugens (Hemiptera: Delphacidae) in the Vietnamese Mekong Delta

In migration analysis of the brown planthopper, Nilaparvata lugens (Stål), in a tropical region, it is difficult to know the arrival timing of the immigrants because rice plants in different growth stages are simultaneously cultivated, and local insects may already occur in destination areas. Due to this analytical difficulty, additional information is necessary to discriminate between immigrants and locally originated individuals in the light trap catch. This study applied rice phenology maps retrieved from satellite images to analysis of N. lugens’s migration in the Vietnamese Mekong Delta. The analysis also employed occurrence data by dense light traps and trajectory analysis. The result showed that the occurrence of N. lugens peaked periodically at an interval of 27.2–30 days, changing in association with the rice cropping area in the harvesting stage. For an N. lugens occurrence in late July 2009 in the delta, the rice phenology suggested catch increases in light traps in a destination area could likely be attributed to immigrants from outside the area. Therefore, the migration analysis suggested that N. lugens that emigrated from paddy fields in An Giang and Kien Giang provinces possibly moved to east-neighboring provinces. The migration distance was estimated to be about 100 km at a maximum.