The pilot system for forecasting insect migrations to next two days will be operated during May and June 2008. Forecasts are concentrating on two major pests; namely diamond-back moth and bird cherry aphid. Five to ten pilot users will get automatic SMS warning messages and are able to study the situation more thoroughly via specific web pages. The pilot users report to the study team about their findings and the usefulness of the service. The validity of the service will be tested using field traps

Koistinen, Jarmo

Leskinen, Matti

Markkula, Irmeli

Ojanen, Hannu

Ooperi, Sini

Pylkkö, Pirkko

Raiskio, Sakari

Tiilikkala, Kari

English

Jukuri

Alarm System for Insect Migration using Weather Radars

Warning system for insect migration using weather radars

 110ISSN 1392-3196 Zemdirbyste-Agriculture, vol. 95, No. 3 (2008), p. 110–115  UDK  632.7:314.7 EARLY  WARNING  SYSTEM  FOR  INSECT  MIGRATION  USING WEATHER  RADARS  Irmeli MARKKULA¹, Matti LESKINEN², Pirkko PYLKKÖ³,                      Jarmo KOISTINEN³, Sini OOPERI², Kari TIILIKKALA¹, Hannu OJANEN¹, Sakari RAISKIO¹  ¹MTT Agrifood Research Finland; E-mail: irmeli.markkula@mtt.fi  ²University of Helsinki  ³Finnish Meteorological Institute Abstract Prediction of weather systems has been the principal aim of weather radar since its early history. With polarimetric radar it is however possible to differentiate bird migration, insect migration and drizzle. Migrating insects can cause considerable damage to crops if they are not controlled in time and there is therefore need for pest-insect early warning systems. Rotating tow-nets, yellow sticky traps and suction traps are used for monitoring insects whenever a migration is underway. Our preliminary results suggest that polarimetric Doppler weather radar can be used to detect migrating insects.   Keywords: polarimetric radar, bird-cherry aphid, pest insects, monitoring, rotating tow-net, early warning system. Introduction Large numbers of insects migrate to Finland during the growing season, comprising mostly aphids, butterflies and moths. Pest species migrating in large numbers can cause serious damage to crops. It is therefore essential to be able to inform farmers of the approaching problem as soon as possible. The early warning system consists of three channels: public media, web services and SMS-messages. The aim of the study was to devise an early warning system for impending migration: direction of migration and the quantity of expected insect types. The early warning system was designed by the Finnish Meteorological Institute and the University of Helsinki in co-operation with MTT Agrifood Research Finland.  Materials and Methods The University of Helsinki operates a polarimetric Doppler weather radar at the Kumpula Campus in Helsinki. The radar transmits microwave pulses directed by a scanning antenna in a circular beam one degree wide. The echoes are received and a signal processor calculates various parameters. In addition to reflectivity and radial speed, the radar system also supplies information on polarimetric properties of the  111scatterers. Insects in the atmosphere are an important source of echoes on the radar frequency band employed (C-band, 5.6 GHz). In this study the received echoes were analysed to obtain data on airborne migrating insects. The data produced by several other Doppler radars were also analysed. The radar network consisted of: i) Kumpula radar, ii) an additional Doppler weather radar situated 32 km north of Kumpula, and iii) Doppler weather radars of the Finnish Meteorological Institute network. All the radars used the same frequency band as the polarimetric radar. The migrating insects were monitored with continuous catchment and alarm catchment. From May to the beginning of July airborne insects were collected using six rotating tow-nets and yellow sticky traps. Rotating tow-nets and yellow sticky traps were used at five of the monitoring sites. At one site there was only a tow-net. The monitoring was supplemented with two suction traps, one in Jokioinen (south-western Finland) and the other at Viikki in Helsinki. When favourable weather conditions for insect migrations were estimated, an alarm was given by the Finnish Meteorological Institute and the University of Helsinki and yellow sticky traps were deployed. Selecting the monitoring fields Air flows between the south-east and south-west were most likely to carry migrating insects to Finland and we therefore selected fields that were open towards the south. Our aim was to position the yellow sticky traps in a circle of about 20–60 km from the polarimetric radar in Helsinki (Kumpula) (Figure 1).    Figure 1. Circles indicate the sites of yellow sticky traps and triangles the sites of rotating tow-nets. Suction traps were located in Helsinki and Jokioinen   112Traps Tow-nets were attached to a vertical bar, and they rotated freely on tripods such that their inlets were always directed against the wind. Horizontal cloth bags caught the insects that fell into a sample bottle filled with 70% alcohol (Figure 2). Sites for tow-nets were chosen between Jokioinen and Helsinki such that they were evenly located and easy to reach by monitoring personnel. The traps were set about 2 m from the ground on the fields. The Kumpula Campus tow-net was located on the roof of the building about 25 m above the ground. The site is surrounded by parks and water areas at the edge of the city centre.    Figure 2. Rotating tow-net being prepared  The tow-net traps were set up on 8th May 2007 and removed on 2nd July 2007. Sample bottles were changed twice a week, usually on Mondays and Thursdays. There were 16 samples from each site except Kumpula, from which there were 20. All the samples were taken to MTT Jokioinen where the trapped insects were photographed and identified. Yellow sticky traps (190 x 320 mm) were continuously located at the same sites as the rotating tow-nets during the monitoring period. They were changed at the same time as the sample bottles of the rotating tow-nets. Sticky traps were fastened to a 65 cm metal stick stuck into the ground. The traps were fastened level with the vegetation. Traps were placed around field edges so that they would not hinder regular field work done by farmers. Yellow sticky traps for alarm catching were set evenly in the Uusimaa area. During the alarm catching period the traps were replaced every second day, enabling frequent assessment of trapped insects. Sticky traps were photographed after removal  113and placed in a freezer to kill the insects. After freezing, traps were covered with transparent plastic for examination and storage. After the freezing phase, sticky traps were examined under the microscope. The most important agricultural insect pests, such as bird-cherry aphids (Rhopalosiphum padi), flea beetles (Phyllotreta spp.) and diamond-back moths (Plutella xylostella) were sorted and identified to species level, but most of the insects were simply identified to family level. Insects kept in the sample bottles (catches from rotating tow-nets) were also examined under a microscope. The preservation liquid was decanted into a counting dish (sector dish) to enable easy sorting of insects and species identification. The level of identification was the same as for sticky traps. Results and Discussion Beetles and radar Flea beetles caused considerable damage to oilseed rape in spring 2007. Daily catches of flea beetles in spring 2007 showed no significant peaks during favourable meteorological conditions for wind assisted migration. These observations indicated that a large number of the flea beetles in spring 2007 originated from domestic populations.  Airborne insects in southern Finland were caught by a suction trap during 1988–1989 at 160 m above ground level /Kurppa, 1989 a/ and it was established that beetles accounted for less than one percent of the catches. As the radar levels were usually above 100 m altitude, the abundance of flea beetles in the fields was not necessarily associated with significant radar echoes.  At the radar site and in Viikki near the coastline, flea beetles were not recorded before the migration episode at the end of May, in contrast to observations made in Jokioinen. The large number of beetles in the coastal traps was probably related to near surface winds blowing from mainland Finland. The radar echoes at that time showed a near surface maximum connected with the outflow from land areas and a step-like change to much weaker echoes at this height over the sea. In Sweden flea beetle migration from Finland was recorded on the eastern coastline /Solbreck personal comm./, but the role of forced landing in the water and the subsequent wind-drift should be taken into account regarding such observations on migrating beetles.  Moths and radar Diamond-back moths were observed in June near the radar site in Helsinki, but the first preliminary observations were made already at the end of May at the radar site 32 km north of Helsinki. The moths were caught in sticky traps near the coastline month on May 28th and in the Kumpula tow-net during the first days of June. The number of moths caught in the study area did not however exceed the current alarm limit. Nume-rous diamond-back moths were observed by farmers on May 30th in Haukivuori, southern Savo /Piirainen personal comm./, and moths were also seen in the nearby areas of Joroinen, Juva, Pertunmaa and Mäntyharju in early June. These localities in eastern Finland are 200–300 km NE from our study area, and the warmest air mass from the south or southeast during the migration period was flowing from a little further east.  114The moths that arrived in eastern Finland were able to lay eggs, which were however effectively controlled by a rainy period that caused high mortality among the progeny. The second generation migrated westwards on July 7th. Those insects probably originated from more eastern or southeastern areas, where the migration at the end of May was characterised by more favourable air currents than those present in eastern Finland. Diamond-back moth migration has been studied using entomological radar /Chapman et al., 2002/, and the University of Helsinki weather radar echo monitoring was once used for near real time warning of a huge immigration episode of the species. Both radar systems are able to detect individual moths and consequently the radar observations can be more reliably related to the migration of the moths. In spring 2007 the moths were not very abundant near Helsinki and their significance in radar echoes was further reduced by numerous other insect species in the air during the warm period of southeasterly flows. However, the second generation migration was spotted by the weather radars in July in a warm southeasterly flow between two precipitation areas. Some other larger insects, probably noctuid moths, were seen in this warm air at nearly 4 km altitude, reaching the freezing level.  Aphids and radar The main immigration of bird-cherry aphids occurred in Finland from May 24th to 28th 2007. Hundreds of aphids were trapped in tow-nets during this period. The maxi-mum number was 166 at Oinasjärvi, roughly 80 km northwest of Helsinki (Figure 3). During the same time domestic bird-cherry aphids were still on the overwintering host (Prunus padus). In the Kumpula tow-net the first two aphids appeared already in the sample from May 14th to 16th and were probably extremely long-range migrants. This period had flows from the south and southwest and long range migrant butterflies (Red admiral, Vanessa atalanta) were also observed in Finland. Rhopalosiphum padi in Tow-nets 2007 02040608010012014016021.5. 24.5. 28.5. 30.5. 1.6. 4.6. 5.6.DateAphidsOinasjärviHoviKumpula Figure 3. High numbers of R. padi were caught in tow-nets late May   115Bird-cherry aphids are not necessarily easily detected in the radar echoes because of their small size. They are much weaker scatterers than certain other insects that migrate at the same time /Nieminen et al., 2000/. On the other hand, if the echoes are mainly caused by these aphids, the migration must be considered substantial. Field observations are very important to verify the radar-assisted warnings for this species. The maxima in field observations of bird-cherry aphids at the end of May 2007 seemed to coincide with maxima for radar echoes over the Gulf of Finland. A cloud of echoes could even be followed in time-lapse images crossing the Gulf of Finland in the southeasterly flow. Moreover, the first period in mid-May was related to significant insect migration detected by the radar. The bird-cherry aphid is the most important insect pest of cereals in Finland and thus the effect of the aphids can be disastrous if the numbers of migrating aphids during the beginning of the growing season are high /Kurppa, 1989 b/. Control is needed if aphids are found on every fifth plant at the shoot or sprouting phase. When the plants are already at the straw phase the economic threshold is 5 aphids/plant and when the plant is producing ears it is 10–20 aphids/plant. In Finland chemical control is usually needed only in years when aphid attack is severe. The best time for application of pesticide is shortly after the aphids migrate and land on the cereal crop. Conclusions 1. It is apparent that although bird-cherry aphids are small they can be detected using radar when they occur in large numbers. Diamond-back moths were also detected with radar. Radar and field trap monitoring of pest insects are important after the aerial migration has begun. Since many harmless species also migrate, vigilance and awareness of the incoming insects are important. 2. In order to be prepared and avoid crop losses a functional early warning system for migrating pest insects is needed. This system also helps to reduce chemical control if carried out early enough after migration has begun. This preliminary study concentrated only on a small area and more polarimetric radars are needed to develop a national system. Received 2008-06-06 Accepted 2008-07-11 REFERENCES 1. Ch a p ma n  J. W., R e yn o ld s  D. R., S mi t h  A. D. et al. High-altitude migration of the Diamondback moth Plutella xylostella to the UK: a study using radar, aerial netting, and ground trapping // Ecological Entomology. – 2002, vol. 27, p. 641–650 2. K u r p p a  S. Predicting outbreaks of Rhopalosiphum padi in Finland // Annales Agriculturae Fenniae 28. – 1989 a, vol. 4, p. 333–347 3. K u r p p a  S. Damage and control of Rhopalosiphum padi in Finland during the outbreak of 1988 // Annales Agriculturae Fenniae 28. – 1989 b, vol. 4, p. 349–370 4. N i e mi n e n  M., L e s k in e n  M., H e l e n iu s  J. Doppler radar detection of exceptional mass-migration of aphids into Finland // International Journal of Biometeorology. – 2000, vol. 44, p. 172–181 

Early warning system for insect migration using weather radars

Organic Eprints

ERAD 2008 ­ THE FIFTH EUROPEAN CONFERENCE ON RADAR IN METEOROLOGY AND HYDROLOGY1. IntroductionThe   Finnish   Meteorological   Institute  (FMI),   MTT Agrifood Research Finland and University of Helsinki (UH) are jointly studying the meteorological circumstances which are a precursor to insect migrations to Finland. The main focus is in the harmful insects such as diamond­back moth (Plutella xylostella) and bird­cherry aphid (Rhopalosiphum padi). The impact of these insects can be drastic if farmers are not able to protect their crops in time. In order to take control measures well in time it is not only essential to forecast the timing and amount of local pests but also of air­borne migrants. In an optimal case farmers can save their crop, money, and environment due to the proper timing.Weather radars are used to monitor insect migrations in progress.   The   radars   used   in   this   project   include  FMI Doppler weather radar network, UH Doppler weather radar 32 km north of Helsinki, and the polarimetric weather radar in Helsinki. These radars all operate on C­band, and most of the clear air echoes that they detect are related to insects in the air. Weather radar information has been used in Finland in studies of insect migrations since the middle of 1980's (e.g. Nieminen et al. 2000). Doppler radars give the average direction and speed, and the polarimetric radar makes the identification of scatterers more accurate.The summer 2008 experiment will be conducted to further confirm presumptions based on earlier 2007 results and to test a pilot alarm­service for selected farmers who will evaluate the usefulness of it. The system will also be verified against the field data on migrating insects. After the summer the results will be analyzed and required enhancements made in order to take a test mode in operation in summer 2009.Fig 1. Insect migration from Estonia to Southern Finland Alarm System for Insect Migration using Weather RadarsAuthors: Pirkko Pylkkö1, Jarmo Koistinen1, Irmeli Markkula2, Hannu Ojanen2, Kari Tiilikkala2, Sakari Raiskio2, Matti Leskinen3, Sini Ooperi3(1) Finnish Meteorological Institute, (2 )MTT Agrifood Research Finland, (3) University of HelsinkiERAD 2008 ­ THE FIFTH EUROPEAN CONFERENCE ON RADAR IN METEOROLOGY AND HYDROLOGYmorning of 29 May 2007. Images from above: dispersion from Baltic states, AVHRR composite of clouds (orange arrows show the insect flow), C­band radar and polarimetric radar2Summer 2007 experiment summer After   the   literature   survey   and   previous   subjective experience it was possible to set up some presumptions of meteorological circumstances connected to insect migration to Southern Finland. These presumptions were tested during May and June 2007 by an experiment. Numerous insect traps   were   distributed   to   the   polarimetric   radar   range. Weather radar data from all sites in the study area, and weather satellite imagery processed in FMI was collected to the   project   archive   during   the   experiment.   Numerical weather  prediction   model,   and   pollen   dispersion   model (Sofiev et al. 2006) information from the period was stored as well. The material collected was analyzed during autumn 2007 and findings were classified to conceptual set of rules for insect migration. These rules form the basis for the warning system.  Fig 1 on right hand side shows a migration case. First image shows the dispersion from the Baltic countries towards southern Finland on the morning of 29th of May 2007. Second image is a satellite image composite showing fog and low stratus (yellow) in central Finland leaving southern coast cloud free. This cloudiness forms a barrier to the insect migration together with the airflow. Orange arrows show the direction of migration. The last two images are from FMI radar network and Helsinki polarimetric radar frpm the same time respectively. Green areas in FMI echo intensity image are related to insect migration. This is verified by the polarimetric radar differential reflectivity image showing mostly more than +7 dB values, especially over the sea.3. Pilot warning service for insect migration 3.1Warning system flowThe warning system consists of automatic calculation of insect   migration   probability,   subjective   control   and correction   tools   of   the   probabilities   and     finally   the dissemination to the users via   web interface and SMS messages.Fig 2. Process flow for the insect warning system3.2 Data sources for the system Basically the same data sources will be used for the insect migration   analysis   and   forecast   as   was   used   for   the experiment on summer 2007.  This means in practice that weather radar data, satellite data and dispersion data will be used in  the automatic analysis  and  prediction. For  the subjective control also the field measurements, forecast model data will be used in addition.3.3 Insect web servicesThe user will be able to examine the end product as a map with verbal comments on the web (Fig 3.)Fig 3. Example of the warning map. The colours show the severity of the warning. Pale green means no warning. The warning is given for seven counties in Southern Finland. The severity of the warning is given as probability class. because the method is experimental and rather rude at present there are only five classes: red meaning probability of migration above 75%, yellow between 50 and 75%, green between 25 and 50%, blue below 25% and pale green no warnings issued.The  user   can   also   examine   real   time  C­band   radar, satellite and dispersion animations on the web (Fig 4.). Summer 2008 there will be only less than ten pilot users. These   users   have   experience   to   use   also   weather information. Therefore one aim is to get feedback from the users, how much they could improve the simple warning information but analysing the weather situation themselves.ERAD 2008 ­ THE FIFTH EUROPEAN CONFERENCE ON RADAR IN METEOROLOGY AND HYDROLOGYFig 4. C­band radar animation. Green colours show weak echoes from insects and birds. Yellow to dark red colours represent rain.3.4 Insect SMS servicesThe warnings will be sent to the pilot users also as SMS text messages (Fig 5).Fig 5. Example of SMS products for insect warningPilot users get automatically the warning SMS text message to their mobile phone. They can also use already existing services to look at the radar animations using wap services.4. Summary The pilot system for forecasting insect migrations to next two days will be operated during May and June 2008. Forecasts are concentrating on two major pests; namely diamond­back moth and bird cherry aphid (Fig 6). Five to ten pilot users will get automatic SMS warning messages and are able to study the situation more thoroughly via specific web pages. The pilot users report to the study team about their findings and the usefulness of the service. The validity of the service will be tested using field traps. Figure 7 shows the locations of yellow sticky paper traps. There will be also several tow nets in the same area.Fig 6. Diamond­back moth (left) and bird cherry aphid (right) are the target insects of the studyFig 7. Map of yellow sticky paper traps (left) and picture of a tow net (right)5. ConclusionsSummer 2008 will be used to study the impact of the insect warning   system.   The   trial   period   will   give   valuable information on how to use C­band polarimetric and Doppler weather radar data to monitor insect migrations. The aim is also to test, when the warnings should be issued and, which is the feasible lead time for warnings to be useful.  AcknowledgmentThe study is conducted under the Finnish Funding Agency for Technology and Innovation (TEKES) funded project “Polarisaatiotutkan monitieteelliset sovellukset” (POMO).References Nieminen, M., M. Leskinen, J. Helenius, 2000: Doppler radar detection of exceptional mass­migration of aphids into Finland. Int J Biometeorol 44: 172­181.Sofiev, M., P. Siljamo, H. Ranta, A. Rantio­Lehtimäki, 2006: Towards numerical forecasting of long­range air transport of birch pollen: theoretical considerations and a feasibility study. Int J Biometeorol 50: 392­402.Corresponding address: Pirkko Pylkkö, Finnish Meteorological Institute, pirkko.pylkko@fmi.fi 

Alarm system for insect migration using weather radars

Alarm system for insect migration using weather radars

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