POTENTIAL OF FORFICULA-AURICULARIA L AS P REDATOR OF PEAR-PSYLLA CACOPSYLLA-PYRI (L)

Potential of Forficula auricularia L. as predator of pear psylla Cacop sylla pyri (L.). Forficula auricularia L. is a well known aphid predat or, and is also described as potentially active on Psyllidae. We studi ed the numeric and spatial components of the predation of F. auricular ia on pear psylla, Cacopsylla pyri (L.) under laboratory and semi-fiel d conditions. At low prey density, a young third-instar larvae consume d as many psylla eggs as Ephestia kueheniella Zeller eggs, offered as alternative prey. The functional response to prey density revealed a m aximum daily consumption of 10 mg per larvae, i.e. more than 1000 psyl la eggs. The tests revealed a density-dependent response, which strong ly reduced the size of large prey groups. Third and fourth instar earw igs consumed all preimaginal psylla instars. In the spring, colonisati on of pear trees by the third instar earwigs coincides with the egg-la ying of the 2nd generation of C. pyri. The natural populations in orch ards of this univoltine and polyphagous predator are little dependent of the prey population. Because of E auricularia high predatory capaci ty, its destruction by chemicals should be avoided in pear tree orchar ds.