Behavioral mechanisms involved in reducing competition in bark beetles

Bark beetles feed and reproduce in the phloem/cambium tissue of trees where severe competition between individuals of the same and different species significantly reduces their reproductive success. In this coevolutionary setting, individuals that can avoid competition whenever possible by means of genetically controlled behavioral mechanisms are naturally selected. Avoidance of intraspecific and interspecific competition is accomplished in part even before landing by olfactory perception of specific pheromones and allomones. These olfactory systems may function at least as well after landing. In several species the uniform distribution of attacks on host trees indicates that individuals avoid competition by only attacking if they are at least a minimum distance from other established attacks. Once beetles are under the bark their tunneling patterns indicate that a behavioral mechanism exists to avoid intersecting nearby galleries of competing individuals. Finally, beetles may choose to re‐emerge if the expected chances of successful reproduction by continuing their stay become less than the probabilities of finding another host and successfully reproducing.