SYMBIOSIS WITH A FUNGUS PRODUCES THE COLORED STRIPES IN SOCIAL WASPS

Composition of the colored stripes in hornets was investigated. In the Oriental hornet (Vespa orientalis) such stripes occur in pairs on the abdomen and on the head, are of a yellow color and stand out from the adjacent brown integument. The pigments detected so far in sd called yellow cuticle are purines and pterdines, whereas in brown cuticle they are melanin. Between stripes of different color there is an electric potential difference (voltage) with the brown stripe comprising an electron donor and the yellow stripe being the acceptor. Close inspection of the yellow stripe reveals it to be composed of the following layers: starting at the top there is the cuticle itself which is composed of about 30 transparent sub-layers, (as compared to about 50 sub-layers in the brown cuticle) below which is a pocket filled with yellow pigment and this, in turn, overlies a basal membrane. The yellow matter appears granular and is composed of an interweave of fibers (made up of fungal hyphae) and branched buds which dries up with maturation of the homer. The hornet apparently ''utilizes'' the yellow pigment in the fungal mycelium as an electric element. Fungal spores occur both on the surfaces of the combs as well as on the inner surface of silk domes of the pupal cocoons, apart from their presence on the adult hornet, where they locate on the bases of the head setae and serve as statolith spores and occur also on other sites of the body surface. It seems that the different colors which occur in the stripes of various social hornets and wasps originate from pigments that are created by various species of fungi. The present study focuses on the collaboration between fungus and hornet and the benefit which each collaborator derives from this symbiosis.