Radar Observation And Population Analysis Of Migratory Insects In North And Northeast Of China

PurposeThe frequent outbreaks of migratory pests is one of the important factors influencing stablble yield of the agricultural production. Excessive pesticide in controlling the migratory pest outbreaks led to ecological and social problem, such as pollution to environment, threaten to food production safety and so on. Therefore, early forecasting is particularly of importance in controlling migratory pests. This paper reported here using the Vertical-Looking Radar(VLR) system to carry out a long-term monitoring to migratory pests, supplemented with captive balloon traping nest, verticalpointing traping searchlight, ground PS-15 Jiaduo traping light and other equipment to collect information of insects from ground to air, made integrated analysis on migratory pests such as the oriental armyworm moth, Mythimna swparata, meadow moth, Loxostege sticticalis, Clover cutworm, Scotogramma trifolii etc. with the data of wind and temperature fields in the ground, the data of low-altitude air airflow and regional circumfluence, insects information elsewhere, crop distribution and result of trajectory analysis during the peak migration period. Research on their migratory paths and rule can provide new technology to migratory pests forecasting and management.Methods1) The vertical-looking radar used in this research was developed in cooperation by Institute of Plant Protection, Chinese Academy of Agricultural Sciences and Chengdu Jinjiang Electronic and technology Ltd. The system operated automatically by microcomputer in signal acquisition, storage and analyses, real-time detect insects and record the time, height and number as they pass directly overhead. The VLR system placed at Zhenlai(45°51'N, 123°12'E) Jilin province from June to September in 2005 to monitor armyworm seasonal migration in northeast of China and discuss the insect origin of outbreaks in Baicheng region field. The VLR was placed at Jining(41°02'N, 113°06'E) Inner Mongolia in 2006²007, mainly carry out radar observation and population analysis for seasonal migration of meadow moth.2) The VLR can operated automatically real-time monitoring and record the seasonal dynamics of insects as they pass directly overhead, which can get time, height, number of migratory insects. Simultaneity, a verticalpointing searchlight, A network of light-traps, an net carried by aerial kytoon (balloon), field investigation and information gathering of migratory insects occur in elsewhere were integrated used to determine migratory species. Physiological characteristics such ovary development were checked to determine migrant or immigrant population.3) Weather balloons tracked by theodolite were released on 20: 00 every night to get wind speed and direction at low altitude during peak period of insect migration for estimating influence of low-altitude air current to insect migratory behavior. According to the relationship between insect migration and low-altitude air curren, we use ArcGIS 8.3 program to draw vectorgraph of wind and regional Circulation at 925 hPa, the data came from the National Centers for Environmental Prediction, to forecast insect migration sources, migration routes and possible landing zones.4) Migratory Insects vertical distribution, relationship between migration and low-altitude air current and vectorgraph of wind of insect migration related were taken into account to ratiocinate immigrant and migrant event in the air. After input GDAS grid data to software Hysplit₄ systems, we spread a number of points within a radius of 111 km around radar observation site to to making trajectory analysis for insect migration. During this reasoning, 20:00 is beginning time for forward trajectory, and so is 06: 00 for backword trajectory, 400 m is start point and maximum height is 2000 m(Beyond the height software automatically stops analysing), we compared this migration routes with the result form above to make a further conclusion.ResultsThis research confirm that migratory behavior parameters and seasonal migration rule of armyworm in northeast of China. The results showed that there were 3 times significant migration process in 2005. Temperature, wind speed and direction in the atmospheric boundary layer, in which most insects flying, do a greater influence on armyworm migrating. Height they flying at were different either in different seasons or in different time in one evening. In spring, they taken advantage of the wind to transmit a long-distance journey, most of the individuals can complete the whole night flights, formed high-density layer centering at approximately 300⁶00 m height from ground. In summer, flight activities were more complicated, the flight of foraging or courtship or mating response, short-distance dispersal and migration often happened mixed. which result in layer outlooking of radar echoes on PPI. The maximum flight height was up to 1000 m, mainly centered from 500 m to 700 m. In fall, they flied relatively lower, most heitht was less than 300 m or concentrations at 400 500 m.Second , it is the first time in China that we proved that ground beetles and clover cutworm can migrate.The data in 2005 showed that the average ground temperature under 20cm in the middle May was lower than the developmental threshold temperature for eclosion of the hibernated chrysalis;Airflow analysis of the late May in 2005 showed that south and southwest winds were preponderant in those days, which provide advantageous airflow for insect migration; The ovarian development of the migrating moths is of same typical characters with migratory insects. Simultaneous radar observations indicated that the nocturnally migrating clover cutworm generally flew at altitudes of up to 1000 m (agl), with high density concentrations at about 300⁵00 m (agl). there are flying moths in 500m(agl) for a whole night. Carabids density is relative higher from late July to late August, the numbers in trap-light catches increase suddenly and follow sharp drops obviously especially during August. Migration of ground beetles is not a haphazard event, they can take long-distance large-scale seasonal migration under the proper conditions. Flying height of the insect is mainly below 600 m (agl), and most of them fly at the height of 450 m(agl). Thus, the conclusion of several carabids species can migrate nocturnally can provide useful suggestions for further study on the migration of Coleoptera insects.Migration rules and population analysis of meadow moth were deeply studied in north and northeast of China. The data of 2005²007 showed that in spring, meadow moth engaged migration in 300⁶00 m(agl) and concentrated at about 400⁵00 m (agl). there are flying meadow moths for the whole night. Summer flights is mixed with courtship, mating and short-distance dispersal mainly height is below 400 m, flying time concentrated in 20: 00 to 22: 00, there are very few flight individuals in other period. Fall flights concentrated at about 300⁵00 m(agl), most of them can fly all the whole night. Trajectory analysis showed that there were frequent exchanges population of meadow moth between China and abroad, airflow do a great influence to migration of this species , this species took off from large area and landed together due to rainfall which can made great damage to farm and corps. Wu Meng of Inner Mongolia, Yanbei, in Shanxi province, Bashang, in Hebei province are still main region for wintering of meadow moth ,Density of survival individuals after winter has a direct impact on the following year occurrence.Innovation1) It is the first time in China that we used the VLR system to carry out a long-time automatically monitor on seasonal migratory insects in north and northeast of China. which are of great significance in studying other migratory insects in China, especially for quantifying variations of biology mass from year to year. we also provide a set of practical new methods and technology system for insect migration monitoring and forcasting.2) In this research, we applied the VLR technology, GIS software etc statistical analysis to develop real-time, automatically monitoring and trajectory analysis of migratory insects. The results from this research was coincident with insects occurred in field. For migratory insects early warning to explore a new research methods.3) Migration route, migration laws of armyworm and meadow moth were made much more clear in this research.4) We proved that ground beetles and clover cutworm migrated in China for the first time. In this paper, a long-term automatically intensive research on insect migration was carried out with the VLR system in north and northeast in China, moreover quantifying variations of biolgy mass over time. dynamic of migratory insects was record in real time, we will provide a new research methods for insect migration and accumulated a considerable amount of research experience in using the VLR technology to research.