Autökologische Untersuchungen an Populationen der gemeinen Kiefern‐Buschhornblattwespe Diprion pini (L.) (Hym.: Diprionidae)

Studies on the autecology of the common pine sawfly Diprion pini (L.) V. Investigations on the larvae parasitic Tachinids, particularly Drino gilva Htg. Drino gilva (Htg.) and D. inconspicua (Meig.) (Tachinidae) are important larval parasites of the common pine sawfly Diprion pini (L.) (Diprionidae). Another species, Diplostichus janithrix (Htg.) is constant, but much less abundant, than the two Drino ‐species. A fourth, Blondelia inclusa (Htg.), is rare. The sex ratio of the first two species is 1:1. The biology of D. gilva is described with special reference to egg‐laying behaviour and development periods. It has two generations a year in the lowlands and one in the mountains. Up to 12% of the sawfly larvae succeed in encapsulating the larvae of D. gilva . The first two larval stages develop within the host's head capsule, causing malformations apparent in the adult stage. In three samples, superparasitism ranged between 68% and over 90% with 2.5 to 3.5 parasites per host. Multiparasitism and interspecific competition are pronounced at high rates of parasitism. Twenty eight different combinations of multiparasitism were found by dissection. Two aspects of synchronisation (seasonal‐ and prolonged diapause‐), between Tachinids and the common pine sawfly, are discussed.