The Storage of Ambrosia Fungus Spores by the Pitted Ambrosia Beetle, Corthylus punctatissimus Zimm. (Coleoptera: Scolytidae)

Extract

During the course of a study of the bionomics of the pitted ambrosia beetle, Corthylus punctatissimus Zimm., in southern Ontario in 1959, the method of overwintering fungal spores and their transmission from brood galleries to healthy plants by the beetles was determined. This process was not clearly understood with respect to any of the ambrosia beetles until recently when Francke-Grosmann (1956) described in detail the different structures, present in several species of Platypodidae and Scolytidae, used in storing fungal spores. In Scolytidae she found that the females of some Trypodendron species store spores in tube-like structures within the prothorax (invaginations of the prothoracic wall); that females of Xylosandrus germanus Bldf. and Anisandrus dispar Fabr. keep spores overwinter in shallow pouches in the intersegmental membrane between the pronotum and mesonotum; that females of Xyleborinus saxeseni Ratz. store them in a small cavity at the anterior edge of the elytra; and that females of Xyleborus pfeili Ratz. store the spores in a receptacle on the “posterior” abdominal tergite. In some species of Platypodidae she found somewhat similar structures in both males and females. In 1959 Fernando (1959) described spore storage by the shot-hole borer, Xyleborus fornicatus Eichh. He found that females store spores in sacs on either side of the head, situated anterior to the brain, and that the sacs open by ducts into the upper part of the oral cavity.