Nocturnal Migration of Coleoptera:Carabidae in North China

Vertical-looking radar （VLR） has allowed long-term automatic monitoring of the altitudinal and temporal dynamics of high- flying insect populations. To investigate whether ground beetle, insect of Coleoptera, was capable of migrating and its migration pattern by taking advantages of capability of the VLR for long-term real-time automatic monitoring, the migration of Coleoptera ground beetle was investigated by setting up radar observation points, making long-term observation using the VLR and related supplementary equipment, and analyzing low altitude air current and large area circulating current in combination with the meteorological data. Information obtained in 2005 and 2006 showed that the seasonal activities of ground beetles traps of trap lamps were mainly from late June to late August, peak period was mainly in August, seasonal traps of high-altitude lamps and ground lamps were featured by sudden increase and sudden decrease; in peak period, the height of radar echo point could be as high as 600 m, while it was mainly below the height of 450 m; night activities mainly occurred from 20：00 to 22：00, in very few nights, radar echo could last until about 04：00, changes in numbers of ground beetles within the searchlights were consistent with radar echo intensity; ground beetle images were successfully trapped in the sweep nets carried by captive balloons at the height of 200 m. Some species of Carabidaes had some degrees of migration, thus providing the foundation for investigating the migration of Coleoptera insects.

INFLUENCE OF THE ASIAN SUMMER MONSOON ON THE MIGRATION PHENOLOGY AND POPULATION DYNAMICS OF NILAPARVATA LUGENS(ST?L) IN CHINA

With the aim to examine variations in the migration phenology and population of N. lugens along with the advance/retreat of the Asian summer monsoon(ASM) and lay the foundation for further study on predicting the timing and location of N. lugens outbreak, correlation analysis and spatial analysis were applied for estimating the impact of the ASM and its related meteorological factors on the migration phenology and population of N. lugens in China in this paper. The ASM had a positive effect on the occurrence and outbreak of N. lugens. First, the first appearance date of N.lugens was consistent with seasonal advances of the northernmost location of the ASM, and the ASM provided the dynamic condition for the northward migration of N. lugens. Second, outbreak of N. lugens occurred in the area under the control of the ASM, and the ASM provided the survival condition for the population of N. lugens. Third, the population was positively related to the northernmost location of the ASM, θ_E(850 hPa) and wind speed(850 hPa).Particularly, the stronger southwest wind caused the date of the first, peak and last catches of N. lugens to turn up earlier than in the extremely years.

Overseas immigration of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), invading Korea and Japan in 2019

The fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith),spread rapidly in Africa and Asia recently,causing huge economic losses in crop production.Fall armyworm caterpillars were first detected in South Korea and Japan in June 2019.Here,the migration timing and path for FAW into the countries were estimated by a trajectory simulation approach implementing the insect's flight behavior.The result showed that FAWs found in both South Korea and Japan were estimated to have come from eastern China by crossing the Yellow Sea or the East China Sea in 10–36 h in three series of migrations.In the first series,FAW moths that arrived on Jeju Island during 22–24 May were estimated to be from Zhejiang,Anhui and Fujian Provinces after 1–2 nights’flights.In the second series,it was estimated that FAW moths landed in southern Korea and Kyushu region of Japan simultaneously or successively during 5–9 June,and these moths mostly came from Guangdong and Fujian Provinces.The FAW moths in the third series were estimated to have immigrated from Taiwan Province onto Okinawa Islands during 19–24 June.During these migrations,southwesterly low-level jets extending from eastern China to southern Korea and/or Japan were observed in the northwestern periphery of the western Pacific Subtropical High.These results,for the first time,suggested that the overseas FAW immigrants invading Korea and Japan came from eastern and southern China.This study is helpful for future monitoring,early warning and the source control of this pest in the two countries.

AUTOMATICALLY OPERATING RADARS FOR MONITORING INSECT PEST MIGRATIONS

Over the last three decades, special purpose “entomological” radars have contributed much to the development of our understanding of insect migration, especially of the nocturnal migrations at altitudes of up to ～1 km that are regularly undertaken by many important pest species. One of the limitations of early radar studies, the difficulty of maintaining observations over long periods, has recently been overcome by the development of automated units that operate autonomously and transmit summaries of their observations to a base laboratory over the public telephone network. These relatively low cost Insect Monitoring Radars (IMRs) employ a novel “ZLC” configuration that allows high quality data on the migrants' flight parameters and identity to be acquired. Two IMRs are currently operating in the semi arid inland of eastern Australia, in a region where populations of migrant moths (Lepidoptera) and Australian plague locusts Chortoicetes terminifera (Orthoptera) commonly originate, and some examples of outputs from one of these units are presented. IMRs are able to provide the data needed to characterize a migration system, i.e. to estimate the probabilities of migration events occurring in particular directions at particular seasons and in response to particular environmental conditions and cues. They also appear capable of fulfilling a “sentinel” role for pest management organisations, alerting forecasters to major migration events and thus to the likely new locations of potential target populations. Finally, they may be suitable for a more general ecological monitoring role, perhaps especially for quantifying year to year variations in biological productivity.

Brown planthopper Nilaparvata lugens was concentrated at the rear of the typhoon Soudelor in Eastern China in August 2015

Sometimes, extreme weather is vital for the population survival of migratory insects by causing sudden population collapse or outbreak. Several studies have shown that rice planthopper migration was significantly influenced by typhoons in eastern Asia. Most typhoons occur in the summer, especially in August. In August, brown planthopper Nilaparvata lugens （Stal） migrates northward or southward depending on wind direc- tion, and thus typhoons can potentially influence its migration process and population distribution. However, this has not yet been studied. This paper reported a case study on the effects of Typhoon Soudelor on the summer migration of N. lugens in eastern China in 2015. The migration pathways of N. lugens were reconstructed for the period under the influence of a typhoon by calculating the trajectories and migration events in eight counties of the Yangtze River Valley region with ancillary information. Trajectory mod- elling showed that most migrants took short distance migrations （less than 200 km） under the influence of the Typhoon Soudelor. Numerous N. lugens migrants were concentrated and deposited at the rear of the typhoon during the last 5 days of Typhoon Soudelor on August 9-13 due to horizontal convergence, and this led to an outbreak population. These results indicated that the N. lugens population was redistributed by the typhoon in the sum- mer and that the population dynamics at the rear of a typhoon should be kept under close surveillance. This study provided insight into migratory organisms adapting to atmospheric features.

Male nutritional status does not impact the reproductive potential of female Cnaphalocrocis medinalis moths under conditions of nutrient shortage

In addition to sperm,some accessory substances transferred to females during copulation act as nuptial gifts by passing on valuable nutrients in many insect species.The nutritional status of the males can thus have a great effect on the mating behavior,fecundity and even the longevity of females.However,little is known about the effect of male nutritional status on the female reproductive traits in migratory insect species,particularly when females experience nutrient shortage and have to choose between reproduction and migration.Here,Cnaphalocrocis medinalis,a migratory rice pest in Asia,was studied to explore this issue.Our results showed that in male moths fed with honey solution,their gonads had higher energy content than gonads of starved males,resulting in increased energy content of the bursa copulatrix of females after mating with fed males.Such females showed increased mating frequency,fecundity and longevity compared to females mating with starved males,indicating that male moths deliver nuptial gifts to females and improve their reproductive performance.However,when females were starved,only about 45%mated,with just a single copulation,regardless of male nutritional status.Starved females showed lower fecundity,and a longer pre-oviposition period(indicating a greater propensity to migrate),compared to fed females.However,copulation still significantly extended their longevity.These results suggest that starved females invest in migration to escape deteriorating habitats,rather than investing the nuptial gift to increased fecundity.Our results further our understanding of the reproductive adaptability of migratory insects under conditions of food stress.

Long-term temporal patterns in flight activities of a migrant diurnal butterfly

Recent studies demonstrated that the Painted Lady(Vanessa cardui),a cosmopolitan diurnal butterfly performs long-range migration between subtropical Africa and north-western Europe,covered by individuals belonging to up to six generations.Here we analyze temporal patterns of complete annual migratory activity of the Painted Lady in Hungary,located in its Central European migratory route,almost completely unstudied before.To do so,we used field occurrence data collected between 2000 and 2019 and estimated temporal patterns in migratory activity by fitting kernel density functions on the daily mean number of individuals and observation frequency.The temporal distributions of kernel density estimates were analyzed as a function of time and key climatic predictors of the study area.We found that(i)the timing of spring arrivals has been advancing;(ii)the relative intensity of the first and last migratory peaks of the Painted Lady significantly increased during the past decades;and(iii)intensity of the last migratory peak is related to the mean temperature of the previous month,inferring that the migration is shifting to earlier dates and their volume of the migration has substantially intensified,evoking mutually nonexclusive,competing hypotheses.Our study indicates the strengthening migration activities of a southerly distributed,long-distance migrant diurnal butterfly,most probably linked to the northward shift of wintering areas induced by warming trends of the southern parts of Europe.However,the complexity of the likely processes leading to changing migratory strategies calls up for further research in both breeding and wintering areas.