Situation of Diabrotica virgifera in Serbia (YU)
During the International Workshop "Western Corn Rootworm in Europe 95", which took place in Gödöllö (HU), 1995-11-08, the present situation of Diabrotica virgifera (EPPO A2 quarantine pest) in Serbia was presented. It can be recalled that D. virgifera was observed for the first time in the vicinity of Surcin airport, near Belgrade, on a small maize plot (0,5 ha) in July 1992. It is thought that it may have been introduced in 1990, by air transport, from North America. The pest multiplied and spread during 1993 and 1994. The main direction for spread was towards the north-west; in general, the main movement of the populations followed the prevailing winds (see EPPO RS 95/116). Monitoring of the pest populations has continued in 1995, by visual inspections and use of cucurbitacin traps. During this year, spread of D. virgifera was observed towards the north (40-50 km compared to 1994), towards the west (10 km) and the east (10 km). The density of the pest, as well as the intensity of attack, diminished with the distance from the first focus near Surcin airport. Damage observed in Serbia is still not very significant. In 1992, only 0,5 ha was concerned, with a medium attack; in 1993 D. virgifera occupied a much larger area (110.000 ha) but damage was seen only on 6 ha. As 1993 was a very dry and warm year more than 80 % of the plants in these 6 ha were severely damaged and no harvest was obtained. In 1994, the infested area reached 200.000 ha, and approximately 70 ha were damaged. The intensity of the damage was moderate, as a harvest could be obtained. In 1995, 275 ha of maize were damaged, and the intensity of damage can be considered as low to medium. In Serbia, 50 to 70 % of maize is grown in monoculture which is a favourable factor for the development of D. virgifera. For the moment, the only control method applied in practice is crop rotation, essentially with wheat and sunflower. D. virgifera has not been observed on these crops. However, as chemical control would be needed in the future, several trials on insecticide efficacy have been carried out in 1994-1995. Trials are made on plots of 100 m2 with 4 replicates, in fields where more than 20 beetles per plant can be found. The economic threshold is approximately of 1 adult per plant. Treatments were made before sowing, at sowing or during the growing season. The best results were obtained respectively, before sowing with terbufos, lindane and bifenthrin; at sowing with terbufos, chlormephos, lindane and bifenthrin; during growing season with carbosulfan, terbufos and phorate. The best protection is obtained with a treatment at sowing.
Sources
International Workshop "Western Corn Rootworm in Europe 95", Gödöllö (HU), 1995-11-08.