A Preliminary Study On The Migration Of Moths Using Weather Radar

In recent years,the occurrence and scale of migratory pests are increasing,among which the moths migrating at night are the main one.Therefore,it is particularly important to conduct large-scale monitoring and early warning for their occurrence.Weather radar,as a tool for automatic monitoring atmospheric sounding,has a wide layout covering our country’s main crop production areas,and the many years of accumulated data contains a large amount of biological echoes information.At present,there are few domestic researches on weather radar biological echoes analysis,and there are few attempts to use weather radar to monitor the occurrence of migratory pests.Therefore,based on the CINRAD weather radar data from Beijing in 2013 and two nocturnal moth migration cases with different migration scales,the study was carried out.The results show that:1.Characteristics of Weather radar echo during days of peak migration of moths in Beijing areaIn order to accurately explore the characteristics of clear air echoes caused by the nocturnally migrating moths in Beijing,the dates where the searchlight trap was full of nocturnal migration of moths,such as Loxostege sticticalis,Mythimna separate(Walker),and Xestia cnigrum,were selected in Yanqing in 2013,and based on this,we selected the clear air echoes with no obvious precipitation at night in Beijing area.The results showed that the night echo and the clear air echo were basically similar except for the interference of strong echoes such as ground echoes,and the clear air echo values were mainly distributed in the range of-10 d BZ to 20 d BZ,which was similar to the insect echo on foreign weather radars.At nocturnally migrating moths peak night,there was a clear rhythm in the clear air echo,which dropped rapidly after sunset and then rises to a high position,and then decreases again with the dawn,which was the same as the rhythm of the nocturnally migrating moths.2.The aerial biomass analysis of oriental armyworm based on weather radar dataBased on the volume filling hypothesis,combined with the searchlight trap data from the Yanqing monitoring point in 2013 on the day of the armyworm outbreak and the echo intensity detected by weather radar,the population size of the aerial armyworm under different elevation angles and different sampling methods on 4 peak days was calculated.The results were as follow,because the weather radar covered a wider area and could detect the movement of the aerial insects earlier,the population numbers calculated by the radar tend to rise before the lights.Not only that,the larger sampling space and area also led to the population size estimated by weather radar is much larger than trapped under the light.3.The source analysis of S.frugiperda based on track and weather radarThe Yanqing monitoring site in Beijing was located in the northern part of North China,and was the northernmost point where S.frugiperda moved northward in 2019.In 2019,while using searchlight and pheromone traps to monitor,with the help of meteorological data,weather radar data and insect trajectory simulation methods,we analyzed the weather background field where S.frugiperda migrated in the Yanqing area,and explored the distribution of potential insect sources.The results showed that searchlight trapped moths earlier than pheromone traps,and the searchlight trap moths were mainly concentrated in the latter half of the night,accounting for 75.0%.The weather background field showed that the north-south air currents can attract the grass moths.The southerly wind accounted for 86.1%,which was much larger than the northerly wind.The moth trapped account for 91.7% during the downdraft period,indicating that the downdraft was favorable for its landing.Weather radar images showed that the heavy rain from the night of October 3 to the early morning of the next day was the main reason for the rapid increase in the population of S.frugiperda that night,and it also shows that the fine-scale atmospheric environment can more accurately indicate the mechanism of nocturnally migrating moths migration and landing.The trajectory simulation results showed that the inbound population may come from Shanxi,Hebei,and Henan provinces which were located south of Yanqing District by means of high-altitude carrier airflow.