Ecological dynamics of ambrosia beetle species in laurel wilt infected trees

The redbay ambrosia Xyleborus glabratus beetle has emerged as a significant pest of Laurel trees, Persea spp. [Laurales: Lauraceae], in the southeastern USA due to its symbiotic association with the pathogenic fungus Harringtonia lauricola , the causal agent of the laurel wilt disease. We evaluated the interaction of different species of ambrosia beetles with redbay trees Persea barbonia infected by H. lauricola. We measured the landing and emergence rates of different ambrosia beetle species throughout the wilting process at different heights. We assessed landing height passively in two redbay stands by placing staggered, unbaited white sticky traps at three height levels (low: 0–1 m; middle: 1–1.5 m; high: 1.5–2 m). We collected nine other Scolytinae species including Xyleborus volvulus , Xyleborinus saxesenii , Euplatypus compositus , Xyleborus bispinatus , and Xyleborus affinis . In the three experiments and both locations, the primary vector of H. lauricola, X. glabratu s, was the most frequently collected species both in the landing captures and in the emergence rate, independently of the wilting status of the host. However, the numbers and diversity of ambrosia beetles landing on trees and emerging from logs increased when trees were in an advanced stage of wilting. Our results indicate that other ambrosia beetles benefit marginally from laurel wilt and that the contribution of secondary ambrosia beetle vectors in the spread of H. lauricola through lateral infection in the redbay system is most likely minimal as compared to the contribution of X. glabratu s.