Situation of Diabrotica virgifera virgifera in the EPPO region
The situation of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) in Europe was reviewed during the 6th Meeting of the EPPO ad hoc Panel on D. virgifera held jointly with the 8th International IWGO Workshop on D. virgifera in Venezia, IT, 2000-10-29/30. In summary, D. virgifera has continued to spread in 2001 (see figure 1) but at a slower pace in some countries in Central Europe, due to the very hot and dry climatic conditions. In 2001, it has been found for the first time in Ukraine, in the Zakarpatya region (part of the country lying west of the Carpathians, near the Romanian and Hungarian borders). The situation in Italy and Switzerland in 2001 has changed considerably. Although eradication is continuing in the Veneto region, it appears that the findings made in 2000 at Lugano/Agno airport (Ticino, Italy) and near Malpensa airport (Lombardia, Italy), which were previously considered as spot introductions, are in fact parts of a rather large outbreak corresponding to an established population. Eradication of this outbreak in Ticino and Lombardia/Piemonte is not considered feasible due to both extent and level of population.
Figure 1. Spread of D. virgifera in Europe from 1992 to 2001
Prepared by FAO Network / J. KISS and C.R. EDWARDS, based on data provided by Bertossa, Boriani, Festic, Furlan, Gogu, Igrc-Barcic, Ivanova, Omelyuta; Princzinger, Rosca, Sivcev and Sivicek.
In 2001 the monitoring of D. virgifera continued near the airport and in several districts. No D. virgifera was caught.
In 2001, monitoring of D. virgifera continued in Austria. Pheromone traps and yellow sticky traps were placed along the borders with Hungary and Slovakia, along the main roads and the Danube, and in Tyrol. In 2001, no D. virgifera was caught.
Bosnia & Herzegovina
In 2001, the insect spread 30 to 35 km towards the west and south. No damage was observed in 2001.
D. virgifera was found for the first time in 1998 in Bulgaria and it then spread towards the northwest near the Serbian and Hungarian borders. In 2001, the pest continued to spread towards the south and east. It was first found near the cities of Kneja and Stara Planina (near Godetch). So far, no larval damage was seen. However, silk clipping was observed near Prevala. Surprisingly, in the area where the pest had first been observed (region of Lom) no adults were caught in 2001.
D. virgifera was first observed in 1995. In 2000, it infested an area of 14,000 km2. In 2001, pheromone and yellow stick traps were placed on 145 sites. It was observed that the front line of the infestation did not move (only 1 new place was found infested). It is estimated that 15,000 ha were infested in 2001. However, population levels increased (approximately 1.4 increase compared to 2000). Plant lodging and root damage were observed in the eastern part of Croatia.
After the Conference, the EPPO Secretariat received the results of the 2001 monitoring done by the French NPPO. Maize is a very important crop in France. In 2000, 1,790,618 ha was cultivated for grain production and 43,033 ha for seed production, and it is expected that maize production will increase. In 2001, pheromone traps were located at 31 different sites, in maize fields or areas considered at risk (e.g. public and military airports). In 2001, no D. virgifera was caught in France. Considering the presence of the pest in Piemonte in Italy, the survey will be intensified in 2002.
Baden-Württemberg is an important maize-growing area in Germany and is therefore considered at risk. In addition, maize monoculture is increasing. In this Land, monitoring started in 1997. Pheromone traps were placed near airports, motorways, railways, warehouses, custom stations, seed-breeding farms and maize fields. In 2001, no D. virgifera was caught. On the whole territory of Germany, 283 pheromone traps were placed on 147 monitoring sites (covering 9 Länder) and no D. virgifera was caught in 2001.
The first adults of D. virgifera were caught in 1995 in Csongrád county, and the pest rapidly spread over the country. In 2001, adults were caught in all Hungarian counties, and it was found for the first time in Vas, Győr-Moson-Sopron and Szabolcs-Szatmár-Bereg. On average, more catches were made in 2001 compared to the previous year. Larval damage was observed in 10311 ha in several counties (Baranya, Bács-Kiskun, Békés, Csongrád and Tolna), but economic damage was seen only in Baranya, Bács-Kiskun, and Tolna (covering 3058 ha).
D. virgifera was first caught in 1998 near Marco Polo International airport near Venezia. The containment and eradication programme continued in 2001, as required by an Italian Ministerial decree of compulsory control against D. virgifera. As in the previous year, an outbreak area of 1200 ha with a surrounding buffer zone of 35,000 ha was monitored. In this area: 1) 159 pheromone traps were monitored, 2) maize cultivation was totally prohibited on 37 ha and maize monoculture was prohibited in the rest of the zone, 3) chemical treatments against the adults were applied twice in July and August in all maize fields; 4) it was prohibited to move fresh maize out of this zone and to harvest maize before the 1st of October. In the buffer zone: 1) 207 pheromone traps (1 x 1 km grid) and later 430 traps (at increasing distance from the focus area) were placed mainly in monoculture maize fields, 2) chemical treatments were applied twice in July and August in maize fields and their surroundings where D. virgifera were caught. In addition, for research purposes, 132 traps of various types were added in both outbreak area and buffer zone. The 2001 results were the following: In the outbreak area: 3 small maize fields in monoculture were discovered (0.4 ha) and according to the prohibition, they were destroyed. 6 adults were caught and all captures were made at the border of the outbreak area, near monoculture maize fields of the buffer zone. In the buffer zone: 108 and later 49 adults were caught in a monoculture maize field (300 m away from the border of the outbreak area), which was then treated. However, new findings were made outside the buffer zone and therefore two new outbreak areas had to be defined (250 ha close to the initial outbreak area, and 27 ha 3 km away from it). Total costs of this programme in 2001 were evaluated at approximately 83,400 euros. Conclusion was that the interruption of maize monoculture is the key element in the programme and that chemical treatments are effective. Eradication is considered still possible and will be continued on a larger area in 2002.
Lombardia and Piemonte
Extensive monitoring of D. virgifera was conducted in different regions of Northern Italy (Friuli-Venezia Giulia, Veneto, Emilia Romagna, Lombardia and Piemonte). Pheromone traps were placed in monoculture maize fields and near potential entry points such as airports, custom stations, etc. During the last 3 years, no D. virgifera were caught in Friuli-Venezia Giulia and Emilia Romagna. In Veneto, the situation has already been presented above. In Lombardia, 3 adults were caught in 2000 in a few traps placed near Malpensa airport (Milano). In 2001, more than 300 traps were placed in Lombardia. As a result numerous specimens were caught in an area of more than 100.000 ha (including the provinces of Varese, Como, Lecco, Bergamo, Sondrio, Milano, Lodi and Cremona). In Piemonte, several specimens were caught in an area covering 17.800 ha in the province of Novara which borders the infested area in Lombardia. Considering the extent of the infestation in Lombardia and Piemonte, eradication is not considered feasible in these regions. Considering levels of populations, it is no longer considered that the airport of Malpensa was the original point of entry of this large focus (but some place near the Italian/Swiss border). However, in order to limit the spread of D. virgifera, maize monoculture will be prohibited in an area of 5 km wide along the border of the infested area. Information on D. virgifera will be provided to growers and the importance of crop rotation will be emphasized.
D. virgifera was first reported in Romania in 1996 at Nadlac (Arad county), near the Hungarian border. In the following years, the pest has spread towards the north-east and the population levels have increased especially in Caras-Severin, Timis, Arad and Mehedinti counties. D. virgifera has continued to spread towards the east and compared to 2000, three more counties are now infested (Sibiu, Mures and Bistrita Nasaud counties). D. virgifera is now present in 15 out of 22 counties, covering nearly half of the Romanian territory (approximately 1.000.000 ha). However, as 2000 and 2001 have been very hot years, populations remained approximately at the same levels. In 2001, larval damage has been observed in Arad, Caras-Severin and Timis counties but it did not reach economic level.
D. virgifera was found for the first time in Slovakia in 2000 in the south of the country. Monitoring continued in 2001 and showed that the pest has spread towards the north and a little towards the west (approaching Austria). The area infested was respectively, 500 ha in 2000 and 6,300 ha in 2001.
In 2001, 56 trapping points located near the Croatian, Italian and Hungarian borders and in Ljubljana were observed. As D. virgifera is approaching, the number of pheromone traps has increased. D. virgifera was not caught in Slovenia in 2001, but it is feared that it may appear next year.
Four specimens of D. virgifera were caught for the first time in 2000, near the Lugano-Agno airport. As a result, measures were taken to eradicate the infestation and monitoring was intensified. In 2001, a total of 74 traps were placed in 37 sites: 10 in the German-speaking part, 13 in the French-speaking part and 14 in Ticino (including the Lugano-Agno airport). Traps were primarily located along the main transportation routes in the main maize-growing regions. The topography of Ticino shows three different maize-growing regions, each separated by mountains and lakes. In this programme, these topographic zones were called: zone A (border region near Chiasso), zone B (central region including Lugano), zone C (Magadino plain, more to the north). The trapping results were the following. In zone A, a total of 1710 insects were caught (75% of them were caught in a single field which is located near an important railway and road transhipment area). In zone B, a total of 462 insects were caught, equally distributed among the trapping sites. In zone C, only 2 beetles per week were trapped over the monitoring period. In all other regions of Switzerland, no D. virgifera was caught. The numbers of insects caught in 2001 in Ticino indicated that a population is now established near the border area of Chiasso. As the numbers of insects caught near Lugano are less important, it is no longer believed that the airport was the initial focus. The Swiss authorities will prohibit maize monoculture in zone A and B. Transport of silage from zones A and B to C will also be prohibited. Considering the population levels observed in the nearby northwestern Italy, eradication is not considered feasible.
Maize is one of the major crops, covering 1,700,000 ha. During the last few years, a monitoring programme was set up in Ukraine. In 2001, 1200 pheromone and yellow sticky traps were placed over an area of 500,000 ha in 25 geographical regions and 106 administrative units. More attention was given to the regions of Zakarpatya, Chernivtsi and Odessa, which are near Hungary and Romania. In August 2001, D. virgifera was caught for the first time in Zakarpatya region, west of the Carpathians near the Hungarian and Romanian borders (districts of Vynogradiv and Beregove). In total, 50 specimens were caught in 7 locations. Research is being carried out on pheromones and on resistant maize cultivars. An analysis of the geographic and agroclimatic characteristics of Ukraine to predict the spread of D. virgifera in the country was made. Considering the biology of D. virgifera, it is likely to survive on the whole territory of Ukraine. However, maize is usually not grown in monoculture and is not grown everywhere. It was felt that in 2002-2005, D. virgifera will spread actively in the lowland part of the Zakarpatya region and hope that Carpathian mountains will act as a barrier to slow down its spread towards the south (although it is likely that the Danube valley will allow its penetration in this southern region, but hopefully at a later stage). Finally, the risk of spot introduction via road or air transportation to other places in Ukraine has to be considered.
D. virgifera was first found in Europe near Belgrade airport in 1992. Monitoring continued in Serbia. As 2001 was a very hot and dry year, little movement was observed towards the south or west and a decrease in population levels was observed. In 2001, damage was observed on less than 1.000 ha (compared to 50.000 ha in 2000). It was felt that when climatic conditions return to normal, populations might increase again. It was stressed that small farmers in Yugoslavia when faced with the damage caused by D. virgifera have abandoned monoculture and started crop rotation, as a consequence a 30 % reduction of maize cultivation in the last few years was observed. The importance of training farmers on how to assess population levels in their fields and better estimate the need for crop rotation or chemical treatments was emphasized.
Papers presented at the 6th Meeting of the EPPO ad hoc Panel on D. virgifera held jointly with the 8th International IWGO Workshop on D. virgifera in Venezia, IT, 2000-10-29/30.
NPPO of France, 2001-12.