CONTROL OF CACOPSYLLA-(PSYLLA)-PYRI (L) (STENORHYNCHA, PSYLLIDAE) BY JUVENILE-HORMONE ANALOGS

Juvenoids could be a useful tool for the control of psyllids. The 12 n ew juvenoids synthetized at the Institute of Organic Chemistry and Bio chemistry in Prague were tested by dipping the feeding plants in the j uvenoid solution and by indirect contact application on Cacopsylla (Ps ylla) pyri (L.). The tested compounds were mostly less active than the commercial juvenoid, methoprene. However, even the low doses of activ e juvenoids which evoked only small malformations on wings and externa l genitalia of the treated psyllids disabled them from flying and also from copulation. The most sensitive period for juvenoids in psyllids comprises the first 4 days of the last larval instar. Aside from this period, juvenoids failed to evoke any malformation. The investigated j uvenoids were also tested on the main predator of psyllids, the pirate bug, Anthocoris nemoralis (Fabr.), using the indirect topical applica tion. It was found that the sensitive period of these bugs to the test ed juvenoids is restricted to the first 24 h of the last larval instar . Hence, the pirate bug revealed very low sensitivity to the tested ju venoids.