BENEDEK P.
University of Agricultural Sciences; H-9201 Mosonmayarova, Var 4., Hungary
E-mail: benedek@movar.pate.hu

Sex trapping studies were organized from 1997 to 1999 at four localities in Southern Hungary close to the Yugoslavian and the Croatian border, resp. Studies were made at large maize field of big farms.

The aim of the trapping was to discover how WCR populations grow up during consecutive years and also additional field observations were made to explore the field damage if any.

Sex trap catches increased rapidly in consecutive years. The rate of in crease, however, was different at localities and years. In general WCR populations multiplied 3-6 times between 1997 and 1998 and as much as 5-25 times between 1998 and 1999.

Scattered field damage was observed in 1998 and 1999 but it did not reach economic level so for at any of the localities inspected.

Two peaks were observed in the seasonal flight activity of beetles. The early one appeared in early to mid July and the late one in early to mid August. It is concluded that the early peak was produced by local WCR populations emerging from pupae in the field inspected or in its immediate vicinity. The late peak however, might be the consequence of the increased activity of beetles when leaving their original breeding habitat and invading another areas.

The ratio of the two peaks was different at different occasions. Results indicate that the early peak is the stronger or the two peaks are similar at those instances when the WCR has well established already at the maize field (and/or its immediate vicinity). At those places, however, where the late peak is the stronger new invasion is intensive from outside and the established local population is rather weak. It is concluded therefore, that probably no early but only late peak would appear at newly invaded areas and so the absence of the early peak can show that the area (field) trapped has probably been free of local WCR population.

This research was supported by IKR Rt. Babolna, Hungary.