A NEW STRATEGY FOR THE ECOLOGICAL CONTROL OF THE GYPSY-MOTH (LYMANTRIA-DISPAR, LEPIDOPTERA)

An experimental model and a new strategy of ecological control of the gypsy moth have been developed based on field data taken in 1991-1995, i.e. during population density increase of the pest. The main advanta ge of tile new conception is a minimisation of defoliation caused by t he gypsy moth. The term ''advance control'', or ''control in advance'' was introduced for treatments, made in the beginning phase of an incr ease in the gypsy moth population. The advance control consists of the following-steps: A. Systematic pheromone monitoring in outbreak; focu ses; B. Signalisation of pest abundance changes by pheromone monitorin g (on the average 60 males per 1 trap); C. Confirmation of the populat ion density increase using the modified Turcek method (critical values are range from 0.05-0.20 egg masses per 1 tree); D. Analysis of abund ance increase conditions, i.e. minimum 4 years since last outbreak, an d dry and warm weather during spring; E. Treatment preparation if crit eria from steps C and D are fulfilled; F. Application of biopesticides : either a half dose of Bacillus thuringiensis preparation (20-30 BIU/ 1 lia applied by ULV technology), or a full dose of virus preparation based on Borrelina reprimens (5 x 10(11) - 1 x 10(12) PIBs/ha).