THE ROLE OF PHEROMONES, KAIROMONES, AND ALLOMONES IN THE HOST SELECTION AND COLONIZATION BEHAVIOR OF BARK BEETLES

Bark beetles use a complex chemical communication system to locate a new host, upon which they can feed, mate, and reproduce. Because the food resource may be either ephemeral (7) or not available until the tree dies, these beetles have evolved a pheromone that elicits behavior resulting in aggregation of the population on the new host. This population aggregation must be both timely and, with tree-killing species, of a sufficient magnitude to exploit the new resource. Because of their capacity to kill living trees, often over very large areas, bark beetles influence age, size, and species distributions, and thus are a significant factor in forest succession. Scolytidae is one of very few insect families in which the adult can penetrate the protective outer bark of woody plants. This behavior facilitates the introduction of pathogenic and decay-causing fungi, which are essential to recycling nutrients from these longest-lived plants.