Aspects of the ecology of siricid woodwasps (Hymenoptera: Siricidae) in Europe, North Africa and Turkey with special reference to the biological control of Sirex noctilio F. in Australia.
Collections of siricid-infested coniferous trees were made in 150 localities in 19 European countries, Turkey and North Africa to obtain parasites and parasitoids of siricids for use in the biological control of Sirex noctilio F. in Australia. During this work, information was obtained on the distribution and biology of 8 siricid species (S. noctilio, S. cyaneus F., S. juvencus L., Urocerus augur (Klug), U. gigas (L.), U. sah (Mocs.), U. fantoma (F.), Xeris spectrum (L.)) and 7 parasitoids (Rhyssa persuasoria (L.), R. amoena Grav., Pseudorhyssa maculicoxis (Krchb.), Megarhyssa emarginatoria (Thnb.), Ibalia leucospoides leucospoides (Hochenw.), I. rufipes drewseni Borries, Odontocolon geniculatum (Krchb.)). Data are presented on distribution, flight periods and sex ratios (determined from emergence records), factors leading to the susceptibility of timber to siricid infestation and the types of timber and host tree species infested. Levels of parasitism by the various parasitoid species, determined from emergence records, are given. Localities are assigned to bioclimatic categories, and their siricid and parasitoid species are classified in relation to the climatic criteria. The ecological status of S. noctilio is discussed in relation to its establishment in Australia.