Effects of Felling Time and Insecticide Treatment on the Interrelationships of Fungi and Arthropods in Pine Logs

Abstract

Small undamaged logs of Pinus sylvestris L. were felled in Feb, May, Aug and Nov, 1966, and stored on the ground in the forest for 3, 6, 9, and 12 months. Half the logs were dipped in insecticide before storage. The position, activity and identity of all fungi and arthropods were recorded on each log. Basidiomycetes invaded the cross-cut ends from Oct to May, and showed no association with bark beetle activity. Bark beetle attack was prevented by insecticide which also lowered the incidence of Ceratocystis spp. Adults of Myelophiluspiniperda L. carried spores of C. piceae (Miinch) Bakshi but its colonization of the tunnels was reduced by prior colonisation by basidiomycetes. Secondary arthropod invaders and other Ceratocystis species invaded M. piniperda systems only when the larvae were well grown and in the absence of basidiomycetes. Adults of Hylastes ater Paykull were accompanied by predatory and fungivorous arthropods and by three species of Ceratocystis. Sciara sp. (Diptera) fed exclusively on Ceratocystis in beetle tunnels. H. ater, and its associated insects are all vectors of Ceratocystis. The suitability of other bark beetles and insects as vectors of Ceratocystis is discussed with emphasis on the importance of egg tunnel orientation and of the feeding habits of the newly emerged adult be etles