G. RIPKA
Central Service for Plant Protection and
Soil Conservation, H-1519 Budapest, P.O.B.:340., Hungary
G. PRINCZINGER
Ministry of Agriculture and Regional Development,
H-1860 Budapest, 55. P.O.B. 1., Hungary
The Hungarian Plant Protection Organisation has carried out a nation-wide survey of western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) in Hungary since 1996. The Plant Protection and Soil Conservation Services in all counties have participated in the study. Similarly to the previous year, in 2001 too, the WCR monitoring system was based on two examinations:
1. Scout trapping
On 49 locations where the WCR was absent
in 2000, Hungarian sex-pheromone traps (Csalomon®) were
placed out in maize fields. In the non-infested areas of 8 counties, the
traps were monitored from 11 June till the end of September at 10-day intervals.
Within 30 days the traps were replaced by new ones.
2. Permanent Monitoring Network
To determine WCR population build-up Hungarian
pheromone traps (Csalomon®) and Pherocon®
AM yellow sticky traps were placed out in pairs on 35 sites of 16 WCR-infested
counties. The distance between pheromone and Pherocon® AM
traps was 50 m. In maize fields the traps were monitored from 11 June to
early October. From 2 July Multigard® yellow sticky trap
and PALs (flower volatile baited) trap were also used for trapping on 15
and 7 sites, respectively. All traps were changed at intervals of 30 days.
Catches were recorded decadely.
WCR was trapped in all (19) Hungarian counties till late August. Out of 49 scout traps, 17 ones had catches over WCR-infested area. These traps caught a total of 316 beetles. The average number of catches was 6,4 adults/trap.
Out of 35 permanent monitoring pheromone traps, 34 ones had catches. A total of 14500 beetles were caught. The average catch was 229,8 beetles/trap. Out of 35 Pherocon® AM traps catches were observed on 25 traps. 2788 WCR adults were captured. The average catch was 79,6 beetles/trap. Multigard® sticky traps caught more beetles, viz. 4403, on average 293,5 beetles/trap than did Pherocon AM traps and pheromone traps. The two trapping systems caught a total of 22007 WCR adults, much more than in 2000 (16211 beetles). In addition the seven PALs traps caught a total of 4077 adults. The average catch was 582,4 beetles/trap. WCR population considerable increased in counties Fejér, Tolna, Somogy, Baranya, Békés and Hajdú-Bihar. At country level most beetles were caught in August, viz. 13672 adults (52,4%), but the catch in July was also high, with 12073 beetles (46,2%). In June 339 adults were trapped only. It is much less than in 2000 (1945). In southern part of Baranya, Tolna and Bács-Kiskun counties on long-term (lasting 5-7 years) continuous corn fields, the adult density was very high in the last decade of July and first decade of August. In these counties several hundreds hectares corn fields were sprayed with insecticides using aerial application, in the beetle control program.
The invasive species was found in counties Vas, Györ-Moson-Sopron and Szabolcs-Szatmár-Bereg where it was absent in the previous year. The farthest point of the WCR spread to the northwest also northeast is about 40 km.
In 10 WCR-infested counties WCR larval damages were surveyed in 955 maize fields on 44895 ha. It is approximately 5% of total maize fields of these counties. Vast majority of the inspected fields was continuous corn field. The Iowa scale was used for the evaluation of root damage. In counties Baranya, Bács-Kiskun, Békés, Csongrád and Tolna larval damages were observed on 10311 ha. In counties Baranya, Bács-Kiskun and Tolna the root damages reached the economic level (3<Iowa scale) on 3058 ha. Lodging plants were found in several corn fields of these counties.