Signals from all sides: Beetle behavior in the presence of symbionts and environmental cues

Non-native ambrosia beetles attack a wide range of host trees causing economic losses in both ornamental and agricultural production. They don’t feed directly on the tree, but rather on fungi cultivated within the galleries bored by gravid females. Ambrosia beetles are of current interest to apple producers in the Eastern United States as they have become associated with Rapid Apple Decline (RAD), a condition affecting young apple trees that ultimately results in tree death. The exact relationship between ambrosia beetles and RAD isn’t fully understood, but current research efforts are under way to study the ecology of two species of ambrosia beetle most commonly associated with RAD; the granulate ambrosia beetle, Xylosandrus crassiusculus (Motschulsky), and the black stem borer, Xylosandrus germanus (Blandford). The work presented here uses population data across varied sites in the Mountain and Piedmont regions of North Carolina to determine habitat types that may act as population reservoirs resulting in greater risk to apple producers. Ambrosia beetle behavioral response to semiochemicals associated with various fungal species is currently being studied and preliminary results will be discussed in the context of the ecological parameters established by the population surveys. The relative importance of the beetles’ behavioral response to various semiochemicals in ecological modeling will also be discussed.