Taxonomy and Systematics of Bark and Ambrosia Beetles

Abstract

1. INTRODUCTION Bark beetles in a wide sense include the true bark beetles (many Scolytidae), which breed in and feed on the phloem (phloeophagous species), and the ambrosia beetles (many Scolytidae, and all Platypodidae), which bore into the wood and feed primarily on symbiotic ambrosia fungi living in the tunnels (xylomycetophagousspecies). Some Scolytidae also develop in hard seeds and fruits (spermophagousspecies), in the central pith of twigs and other small stems, or in the petioles of fallenleaves (myelophagous species). We use the term 'bark beetles' to cover all thesecategories, unless otherwise specified. Bark beetles usually live in scattered habitat units, which are suitable for breeding for only a single generation of beetles. Thismeans that the new generation of adults must disperse to find new breeding sites.These two features mean that bark and ambrosia beetle populations are very variable both in space and time, depending on the spatial and temporal availability of suitablebreeding material. The study of their temporal and spatial dynamics is very important both because of their economic immportance in forests, and the ease withwhich these small beetles can be transported to, and become established in, newareas. The majority of species breed in dead or dying tissues, and are not normallyof economic importance. However, such species can become economicallyimportant if their galleries create holes in timber used for furniture or veneer, or if they transport pathogenic fungi to living trees during a period of feeding by young adults to mature the gonads. The relatively small number of species that attack livingtrees, saplings or seedlings, or the seeds off commercial crops (e.g. coffee, palms) aresometimes of major economic importance, causing damage estimated in millions of