Today's topic is how to put up a no vacancy sign for the Douglas-fir beetles. Most people are aware of the destruction to large swaths of forest trees brought about by a tiny insect group called bark beetles.
In addition to damaging timber resources, beetle-killed trees negatively impact campgrounds' residential sites and increase wildfire severity. Research has found that pheromones, which are chemical cues used in communication within a species, are present in bark beetles and produce two types: aggregation and anti-aggregation.
Aggregation pheromones are released by female Douglas-fir beetles to serve the purpose attracting mates and large numbers of beetles to come and help them overwhelm the tree defenses.
Anti-aggregation pheromones are released by the male Douglas-fir beetle after mating to prevent overpopulation of tree and subsequent larval competition for a limited amount of food. This is essentially a no vacancy sign.
Late arriving beetles receive a signal at the colonize tree is full and continue dispersing to other trees.
In the 1980s, a system was developed to use the beetles with no vacancy sign against them. Continued research is still going to gain a better understanding of bark beetle behavioral responses to pheromones that could potentially lead to more effective pheromone-based management treatment.
For more information on this topic, and others, go to the Entomology Today blog and look up Douglas-fir bark beetle.