Zur Parasitierung der Puppen von Forleule (Panolis flammea [Schiff.]), Kiefernspanner (Bupalus piniarius [L.]) und Heidel‐beerspanner (Boarmia bistortata [Goeze]) in bayerischen Kiefernwäldern¹

Abstract

Abstract On the pupal parasites of the Pine Beauty (Panolis flammea [Schiff.]), the Pine Looper (Bupalus piniarius [L.]) and of Boarmia bistortata (Goeze) in Bavarian pine forests It was attempted to investigate, if economically indifferent hosts can be important as “reservoirs” of the parasites of dangerous pest insects and to get some insight into the cross‐relations between hosts and parasites in the pine forest. Some theoretical remarks on the biology of insect‐parasites (= parasitoids) are brought forward, especially a division of these into “idiophytic” species (consuming the host as it is when attacked) and “koinophytic” parasites (feeding for considerable time on the host when this itself is feeding). From these aspects the different species of the parasites and the parasite ranges of the hosts are discussed. The most important of the (idiophytic) pupal parasites are common to all three of the investigated hosts, but most of the (koinophytic) larval parasites are peculiar to one of them. ‐ In Panolis several pupal parasites are of approximately equal importance, whereas in the two Geometrids one of their pupal parasites is largely dominating, Rictichneumon pachymerus in the case of Boarmia, Cratichneumon nigritarius in that of Bupalus. ‐ As pupae of Boarmia are available almost throughout the year the idiophytic pupal parasites can follow an outbreak of this species, though their development is not synchronized with that of the host. With Panolis and Bupalus the idiophytic pupal parasites are usually predominating in periods of low host‐density. During outbreaks, however, they are often largely outnumbered by koinophytic parasites of the larvae, whose development is coordinated with that of the hosts. ‐ Boarmia bistortata can serve as a “parasite‐reservoir” of forest pests only in respect to idiophytic parasites. As such it may have some effect in preventing outbreaks of the pest, but can not have great influence on the termination of such an outbreak.