I.H. ZSELLÉR
Plant Health and Soil Conservation Station of Csongrád County, H-6801 Hódmezövásárhely, P.O. Box 99, Hungary
E. SZÉLL
Cereal Research Non-Profit Company, H-6701 Szeged, P.O. Box 391, Hungary

As one of the most infested part in Hungary since 1996 the permanent trapping has been continued in four sites in county Csongrád. Observations took place at the same fields in Csanádpalota, Hódmezövásárhely, Nagylak and Szeged using pheromone (Csalomon) and yellow sticky (Multigard and Pherocon) traps.

Besides trapping of adults determination of larvae development was also carried out by weekly root observations.

On each field 10 emergence cages were set up above one corn plant to measure the number of beetles developed within one root system. In the end of the season the damage on roots were rating by the modified IOWA-scale, the yield of each plant was measured and correlation between adults developed in root system and yield production was measured.

Results of permanent trapping showed significant increase in area of Nagylak and Hódmezövásárhely this year. The population established on the same level in Szeged and less number of beetles was caught by the traps in Csanádpalota. Lodged plants were found only in Szeged experimental field.

Development and seasonal flight of WCR can be compared under rather different weather conditions based on data in 2000 and 2001. The weather in the vegetation season of 2000 can be characterized with extremely high temperature without considerable precipitation for a long period. Season of 2001 was less hot and regular precipitation was measured. In 2000 very early larva hatching was observed: on 25 May both L1and L2 stages were found. This year first L1 larvae were detected on 30 May. First males occurred 15 June in 2000 and ten days later, 25 June in 2001 in pheromone traps.

The number of emerged adults in cages was low in Csanádpalota and Nagylak observation fields in both years. In Szeged the number of beetles varied between 4 and 53 per plant in 2000. In 2001 number of adults collected in cages increased and varied between 28 and 218. Significant correlation was observed concerning the number of adults, the root damage and the weight of yield of plants.