I. UJVÁRY, P. SIPOS, Á. BANDINÉ-BARLAI, K. SZÜCS-TÓTH, L. WENNEMANN, H.E. HUMMEL
A number of field experiments have already been conducted to evaluate the impact of the plant kairomone mimic MCA as an orientation disruptant on field populations of the western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) in corn in Hungary and Yugoslavia. Preliminary studies indicated that the application of the non-toxic MCA in corn fields decreased orientation towards MCA and pheromone baited traps The principle of a permeation of a corn field is that the strong smell of this organic substance causes orientation disruption and might mask the female sex pheromone as well.
For the formulation MCA was dissolved in acetone and blended with corn grits (‘grits’) using a cement mixer. Grits, available in different sizes, are a by-product after corn is harvested and separated from the cob. To identify the optimal formulation technique, mixing experiments in 2000 were conducted with different amounts of acetone, various spraying methods (fog or jet) and in a covered or in an open mixer. Samples were taken directly after formulation and on regular intervals for 10 days after grits were exposed to the atmosphere. In 2001, grit samples were taken directly after the formulation and over several days after application in a corn field. The residual MCA of the grits was determined by extraction with ethanol, and UV spectrometric analysis at 320 nm. Furthermore, additional experiments were carried out to determine MCA in the atmosphere. Aerial MCA was absorbed on a charcoal filter within a glass tube attached to an air pump after field treatment at 80 gr./ha in a 12-m2 plot.
MCA release rates were essentially the same for the different mixing techniques. The results of grit extraction and analysis showed that over 85% of the applied MCA can be recovered from the formulation. The MCA content of the grit formulations was demonstrated to decrease exponentially with a ca. 2.5 days half life for the experiments in 2000 and 2001. The MCA collected in the charcoal filter was below the UV-spectrometric detection limit. The project is supported by EU framework 5 project QLK%-CT-1999-01110.