L. WENNEMANN¹, T. TUSKA², I. UJVARY³, E. PETRO⁴, A. PAULIK⁵ & H.E. HUMMEL^1
1 Justus Liebig University Giessen, Institute for Phytopathology and Applied Zoology, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany
² Department of Plant Protection, St. Istvan University, H-2100 Gödöllö, Hungary
³ Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary
⁴ Plant Health/Soil Conservation Station of Budapest, Budaörsi ut 141-145, H-1118 Budapest
⁵ Alkotmany u. 39. sz., H-5820 Mezöhegyes, Hungary

Hummel and Metcalf (l996) and Hummel et al. (1998) (IWGO newsletter 18 (1) 34-35) reported on the ability of the plant kairomone mimic or parakairomone MCA (4-methoxy-cinnamaldehyde) to disrupt orientation of D.v. virgifera in MCA permeated fields for a period of up to 10 days in Illinois (USA). One of the goals of the EU sponsored Diabrotica research project is to evaluate the potential of MCA as an orientation disruption tool in Hungary on a multihectare scale.

First year's studies in Hungary focused on aircraft application technology. Also investigated were formulation techniques of MCA with acetone and corn grit carrier material of uniform particle size, called "granules" for short. Evaluation of distribution patterns of granulates coated with  MCA in the field were additional requirements of the work package. Finally, the impact of MCA on beetle orientation in experimental field sites in Nagylak and Csanadpalota in south-east Hungary was investigated.

For the formulation of MCA disruptant, a novel mixing technique was investigated: A portable cement mixing machine was used to mix MCA dissolved in acetone as a cosolvent with corn granules, a cheap and readily available by-product after corn is harvested and separated from the cob. A 1000 ml plastic hand sprayer served to apply 80 g or 120 g MCA/ha on 18 kg corn granules/ha. The acetonic solution of MCA was sprayed directly into the rotating mixer filled with the granules. The mixture could be stored up to 5 days in closed metal barrels before aerial application.

Several mixing modifications were used in an experimental set up. MCA was dissolved in 300 or 600 ml of acetone and applied with the hand sprayer as a fog or as a liquid jet. The opening of the mixing machine was left open or covered with a plastic sheet with a hole in the centre for spraying a MCA solution into the mixer. Treated granules were afterwards put in plastic dishes and placed outside under field conditions. Subsamples of 5 g each were taken out daily for 10 days. Analyses by gas chromatography and/or spectrometry could estimate the release rate of MCA from the granules. Results, not yet available, will be used for optimising the appropriate mixing techniques.

Field application of granules was accomplished using a Dromader aircraft. Distribution patterns of treated granules were investigated. Plastic dishes (diameter 30 cm) placed in the corn fields collected granules falling to the ground. Additionally, granules settling on leaves and leaf axils were counted. Preliminary results revealed an even distribution pattern of the formulation in the field. Granules could still be found on the plants  after more than 10 days.

The effect of the MCA formulation was evaluated by monitoring beetle counts in pheromone or MCA baited versus control traps in treated and untreated field sections. Traps consisted of inverted plastic cups (500 ml, Polarcup, Hungary) with a pheromone or MCA lure put on filter paper on top of the cups. Unbaited control traps had plain filter paper only. These traps are inexpensive, omnidirectional, quick and easy to prepare and attract beetles very sensitively.

Trap catches were analyzed using Abbott's equation. Preliminary analysis of the field experiments on a 8 ha corn field at Csanadpalota using this particular formulation of 80 to 120g MCA showed some variable orientation disruption of adult western corn rootworm beetles. A reduction of variability is expected from increasing both the size of the treated area and the concentration of the disruptant.

Research in 2001 will focus on intensifying MCA field evaluation by dissecting females and identifying their mating status both in MCA-treated and untreated plots. A suitable 18 ha corn field for next year's experiments has already been identified. Contacts were established to investigate alternatives for aerial application technology. Furthermore, investigations will focus on the minimal distance of pheromone and MCA traps positioned in the field and on flight activities of Diabrotica v.virgifera.