SPATIAL DISTRIBUTION OF TEFLUBENZURON RESISTANCE BY PEAR PSYLLA IN WESTERN SWITZERLAND

摘要

In recent years, pear producers in the region of Lake Leman observed an efficacy reduction of teflubenzuron against pear psylla (CacopsyllapyriL.). Thus, in 1994 and 1995, we conducted experiments in the laboratory to confirm the efficacy reduction and to study the spatial distribution of the resistance in western Switzerland. After application of a registered dose of teflubenzuron, all eight samples from orchards of the region of Lake Leman showed low mortality rates whereas the nine samples from the Valais showed normally high mortality rates. The dose-mortality response of psylla from one orchard of each region is currently being estimated. We conclude that the psylla of the Lake Leman region were resistant to teflubenzuron, Also, psylla from anorganic orchard without any teflubenzuron treatment were resistant. This indicates that movement played an important role in psylla resistance development.