| Recently the outbreaks of the small brown planthopper Laodelphax striatellus (Fallen) had occurred frequently, caused serious damage to rice plants when feeding and transferring viruses. The Jianghuai region, as an important major place of production of wheat and rice, was responsible for the base of agricultural production of China, as well as large strategic significance. Thus, it is extremely necessary to study the occurrence of SBPH. Although it had been regarded to be local pests by domestic scholars, there were indications that they might have migration characteristics and was assured to be migration insects by Japanese researchers. Therefore, the dispersal and migration of SBPH in Jianghuai region was studied in this paper, and it has important practical significance for further improving the disaster warning capabilities.The spring dispersal and migration of SBPH, the source region and destination of migration, the meteorological background was analyzed in four stations located in Jianghuai region of Anhui and Jiangsu province. Meanwhile, the flight capacity and the influencing factors were studied by indoor hanging-wing-beating experiment. The individuals were divided into resistance, migratory and strong migratory type by the accumulated wing beating durations. All above related to flight capacity could provide the foundation for migration.1. Case studies in Fengtai, Anhui province in spring of2009and2010The spring population properties of the1st generation of small brown planthopper (SBPH), Laodelphax striatellus (Fallen), were studied in Jianghuai region of Anhui province through field survey in wheat and rice seedling fields, light-trap catches and ovarian dissection of macropterous females, in order to clarify whether the1st generation of SBPH could take long distance migration in eastern China. The migration pathways of SBPH were simulated and analyzed by HYSPLIT, a NOAA trajectory analysis platform. The results were showed as follows:(1) the population displacements of SBPH in wheat fields during the end of spring included long distance migration between different regions and local dispersal in Jianghuai Region.(2) SBPH dispersed to rice seedling plots from wheat fields just before wheat harvest, or happened as the macropterous adults take-off for migration were arrested by the weather conditions such as precipitation and strong winds.(3) It was revealed by the field surveys and light-trap catches that there were two migratory peaks in spring of2010,5th June and12th June, respectively. The trajectory analysis showed that the population source areas of the former immigration event were from Yangzhou, central of Jiangsu Province and the latter one came from Jining, south of Shandong Province.2. Case studies in Jianghuai region of Jiangsu province,2006-2009The dispersal and migration in2006to2009was studied by means of analyzing the daily light-trap catches and systematic rice seedling fields surveys data, as well as figuring out the long distance migration in Zhangjiagang, Wujin and Yizheng stations of Jiangsu province, part of Jianghuai region. The meteorological backgrounds of migration and landing were displayed by the software GrADS and ArcGIS. Meanwhile, the source regions and destinations of migrations were studied by numerical simulation and trajectories analysis with HYSPLIT simulation platform. The results were as follows:the SBPH transferred to rice seedling fields massively from wheat fields during wheat harvest period in Jianghuai region of Jiangsu province. There were differences among the three stations in light-trap catches in years. Moreover, the year2007turned out to be the maximum occurrence in both light-trap catches and rice seedling fields’surveys extremely in Wujin station.12emigrations or immigrations were figured out by light-trap catches and rice seedling fields’surveys. The backward and forward trajectories were analyzed and we finally got the following conclusions. The emigrations from Zhangjiagang on May282006arrived in Kyushu region in Japan30hours after taking-off, and it was proved by the local light-trap catches peek notes. Emigrations from Zhangjiagang and Wujin on June82006arrived in the border of the North and South Korea. The source region of large immigrations to Wujin on May232007was analyzed, and migrations last within10hours began at the border of Jiangsu, Anhui and Zhejiang province, and that last for24to34hours located in the line of southern Jiangxi to central Fujian. The major factors affecting the landing were the wind shear and precipitation. Emigrations from Zhangjiagang on May252007arrived in Japan and the one on May27arrived in the middle border of Jiangsu and Anhui. Emigrations from Yizheng on June82007arrived in the border of Jiangsu, Anhui and Shandong province. Immigration occurred in Yizheng station on May16to202008due to wind shear, and the source region located in the junction district of southern Jiangsu and southern Anhui. The unknown peaks in light-trap catches were studied by backward and forward trajectories analysis. The results showed that the long distance migration in Jianghuai region of Jiangsu province during wheat harvest period mainly destined to the sea, northern Anhui, northern Jiangsu and Eastern Zhejiang, partially to Korea, southern Anhui, Zhejiang, Shandong and part of Jiangxi, and originated from northern Jiangsu and northern Anhui province. Migration populations taking off in the dusk probably be greater tended to flight oversea.3. Flight capacity of Laodelphax striatellus (Fallen)Flight behavior of Laodelphax striatellus (Fallen) was observed by infrared camera records to study the relationship between sexes, ages, mate status and adults flight capacity. The results indicated that flight duration of2,3and6-day-old adults lasted for long and reduced with the increase of day age, and so it was with the ratio of migration type. Sex had no significant impact on the wing-beat performance of the insect and mate status had impact on the accumulated wing-beat duration of4and5-day-old females. This stage of unmated female adults showed significant shorter wing-beat duration than that of mated ones. There were more differences among individuals above5day age. The strongest individual wing-beated totally for1246minutes and thus can take long distance migration. Based on the accumulated wing beat duration (AWBD) of the macropterous individuals treated, Laodelphax striatellus (Fallen) could be divided into three types:the resistance type (AWBD<25min), the migratory type (25min<AWBD<93min) and the strong migratory type (AWBD>93min). The time scale distribution of wing-beat behavior could be continuous or interrupted, and it performed more frequently wing-beating at dusk, accumulated wing beating duration last for longer, indicated more migration desire. |
PDF Full Text Request