INTERACTIONS BETWEEN THE PHLOEM-FEEDING SPECIES TOMICUS-PINIPERDA (COL, SCOLYTIDAE) AND ACANTHOCINUS-AEDILIS (COL, CERAMBYCIDAE), AND THE PREDATOR THANASIMUS-FORMICARIUS (COL, CLERIDAE) WITH SPECIAL REFERENCE TO BROOD PRODUCTION

Interactions between Tomicus piniperda (L.) (Col.: Scolytidae), Acanth ocinus aedilis (L.) (Col.: Cerambycidae) and Thanasimus formicarius (L .) (Col.: Cleridae) were investigated in caged pine bolts. The treatme nts were T. piniperda alone, A. aedilis alone, T. piniperda together w ith A. aedilis, T. piniperda together with T. formicarius and all thre e species together. T. piniperda offspring production per m(2) was red uced by 92 % when reared with T. formicarius, by 78 % when reared with A. aedilis, and by 94 % when all three species were reared together, compared with T. piniperda reared alone. A. aedilis had a negative inf luence on the offspring production of T. formicarius and vice versa. W hen both species were present in the same bolt (together with T. pinip erda) offspring production was reduced by 74 % for A; aedilis and by 4 2 % for T. formicarius compared with their respective production value s when each species was present alone with the bark beetle. The new ge neration of T. formicarius emerged as larvae from June to August while most of the A. aedilis offspring emerged as adults from September to October, leaving only a few larvae in the bolts to hibernate. A. aedil is only reproduced in a small part of one of the bolts without bark be etles.