Study On The Occurrence Regularity And Migratory Biology Of White-Baked Planthopper Sogatella Furcifera (Horváth)

The white-backed planthopper Sogatella furcifera (Horvath) (WBPH) is one of the most important pests on rice in Asia. Because of its long-distance migration and disaster by landing, severe losses have been caused by WBPH in southern China, which threaten the increased production of high quality, high income in this area. Huizhou is located in lower reaches of Yangze river, is one of the important transit points of the northward and southward migrations of WBPH, thus, the study on occurrence regularity of WBPH in Huizhou will be helpful for further improving the early-warning function of the disaster.The occurrence regularity, soure areas, landing mechanisms and migratory biology of WBPH were studied in this paper. WBPH was trapped by using ordinary incandescent light from 1977 to 2010 in Huizhou, Anhui Province. Population dynamics and occurrence period of the pest based on the 34 years historic data of this area were analyzed. The spatial distributions of source areas of the immigrants WBPH at different generations were analyzed by trajectory analysis under HYSPLIT platform, a simulation tool of migratory pathways. By using GrADS and ArcGIS, the weather backgrounds during the immigration periods were analyzed. The migratory biology of WBPH was analyzed through monitoring data of WBPH in different monitoring sites.1. The case analysis——2009The population dynamics and generation properties of WBPH in Huizhou, southern Anhui Province were studied through systematic field survey and ovarian dissection of macropterous female. By using GrADS and ArcGIS, the weather backgrounds during the major immigration periods in 2009 were analyzed. The spatial distributions of source areas of the immigrated WBPH at different generations were analyzed by trajectory analysis using HYSPLIT platform, a simulation tool of migratory pathways. The main results were as following:The third generation of WBPH provided most damage to the middle and late rice in Huizhou,2009. From tiller to ripen rice stages, the generations next to the immigrations all exhibited chiefly as the emigration, and there was no obvious local breeding generation, as brown planthopper, and the 3rd generation would emigrate but some immigration peaks could be seen synchronously. The population source areas of each immigrant generations were tracked through the trajectory analysis. It was indicated that most of the immigrants came from the southern Hunan Province, the central and southern Jiangxi Province. The appearance of horizontal wind shear, downdraft and heavy precipitation could be the synoptic backgrounds for prediction of the immigration of WBPH in Huizhou, Anhui Province.2. The occurrence regularity of WBPHThere was no overwintered WBPH in Huizhou, it had 4-5 generations per year, its first occurrence date was in late-May or early-June, the middle and last tendays of June was the major immigration period, population dynamics of WBPH showed as single-peak pattern. In other words, there was a peak of damage from late-June to middle-July, which caused by the 2nd generation.3. The distributions of source regions of immigrant WBPHThe percentages of the effective source regions of WBPH were analyzed through different flight altitudes, flight times, immigrating amounts, as well as each ten days and years. The results showed that the percentages of the effective source were 53%, which were consistent from 1500 to 2000 m above ground. The percentages of the effective source of migration were between 45% and 65% in different years, but the percentages of the effective source of migration were higher than others as flight successively for 15-30h, light-trap catches for more than 350 per a day and the periods from late-June to early-July, and their effective percentages were more than 60%,60%,57%, respectively. The results also indicated that the main source regions of WBPH were located at the centre of Jiangxi Province, the interface areas of Hunan, Guangdong and Jiangxi Province. The source regions appeared to be nearer distribution, while decreasing of the successive flying times and the variable of the main immigrating perods; however, different flight altitudes, immigrant amounts and years, the source regions kept basically similar, the source regions were dominating of the centre of Jiangxi Province, the interface areas of Hunan, Guangdong and Jiangxi Province, this was also the medium and small scale source regions. 4. The landing mechanisms of WBPHThe landing of WBPH was affected by unique topography and meteorological factors in Huizhou. Huizhou is located in Huizhou Basin, the southern region of Huizhou is Baiji mountains and the northern is Huangshan mountains. Huizhou Basin acts just as the unique channel for the northward migration of WBPH, which is in favor of its concentrated landing and always become as a insect pest nest. Moreover, the ridge of west pacific semi-tropical high located between 20°N and 25°N, the southwest warm-wet airflow at its northwest side was favorable to carry mass of WBPH into Huizhou. While the cold trough down south from northward frequently joined up with the southward warm, humid air-flow, heavy precipitation would happen and cause the centralized descenting of WBPH. As a result, the unique topography, shear-line, heavy rain and velocity perturbation were the key powerful force for landing of WBPH.5. The migratory biology of WBPHThe take-off behavior of WBPH and its relationship between different generations, in different years and places were studied by means of field observation data analysis and envelop experiment. The relationships between wing polymorphism, proportion of macropterous adults, and rice growth stages, population density of adults and precipitation were analyzed through systematic field survey and dissection of macropterous female ovarian. The main results were shown as following:The 2nd and 3rd generations of WBPH were the main emigration generations in early-mid plant rice field, but the amounts of emigrant were declined significantly since the waxen maturity stage of rice in 2009. The quantities of WBPH emigrant were correlated with adult density; heavy precipitation effected on the take-off amounts of WBPH. There were mainly the macropterous adults in most of the local generations. The dimorphic wing type in different local generations was different from brown planthopper, and exhibited as 'macropterous-macropterous-macropterous'. The take-off and emigrating of WBPH were not relevant to the rice growth stages. The population migratory characteristics of WBPH local generations might be classified as three different types:immigrating type, emigrating mostly but partially breeding locally or immigrating type, emigrating type.