Ambrosia Beetles Prefer Closed Canopies: A Case Study in Oak Forests in Central Europe

Abstract

Research Highlights: The percentage of canopy closure was found to be the main factor associated with ambrosia beetle abundance and species richness. The latter two variables increased as canopy closure increased, probably because a high percentage of canopy closure provides a stable and humid environment suitable for the growth of ambrosia fungi. Objectives: Oak is a common host tree for ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), which have independently evolved a nutritional mutualism with fungi. We suspected that ambrosia beetles might have specific habitat preferences that are different from those of other saproxylic beetles and that reflect the specific habitat preferences of their food, i.e., ambrosia fungi. Methods: We assessed ambrosia beetle abundance with ethanol-lured traps in five old-growth oak dominated forests and five managed oak dominated forests (one trap per forest) during the vegetation period in 2020. We determined whether ambrosia beetle abundance and species richness depend on forest type (managed vs. unmanaged), degree of canopy closure, abundance of oak trees, abundance of coarse deadwood, and abundance of dead oak branches. Results: In total, 4137 individuals of six species of ambrosia beetles associated with oaks were captured. The native ambrosia beetle Anisandrus dispar represented the majority of trapped ambrosia bark beetles. A. dispar along with another ambrosia beetle, Xyleborinus saxesenii, represented 99% of all captured beetles. Conclusions: In addition to canopy closure, the abundance of oak trees and the abundance of dead oak branches were significantly associated with ambrosia beetle abundance and species richness. The abundance of A. dispar was mainly correlated with dead oak branch abundance and the degree of canopy closure, whereas the abundances of X. saxesenii and of the invasive species Xyleborinus attenuatus and Cyclorhipidion bodoanum were mainly correlated with the net area occupied by oak trees.

Vertical Stratification of Beetles in Deciduous Forest Communities in the Centre of European Russia

“…The species was also found on fermenting sap on an oak trunk [78]. Both species of bark beetles Anisandrus dispar and Xyleborinus saxesenii (Ratzeburg, 1837) were caught in the largest number at an height of 1.5 m. The ambrosia beetles Scolytinae (Curculionidae) usually prefer to inhabit the lower parts of the tree crowns, so most of them are trapped at a height of up to 2 m [79][80][81][82].…”

Xylophagous beetles (Coleoptera) in the zones of Gomilshanski lisy National Nature Park with different management regime

“…dispar and X. saxesenii are also the most abundant beetles in different regions ( Bussler et al 2011;Saruhan 2013;Sarikaya 2015;Tanaskovic et al 2016). Both species are polyphagous; however, A. dispar prefers thin branches and X. saxesenii the stem part of the tree (Skrylnik et al 2019;Holuša et al 2021).…”

“…Human activity, in particular, forest management and recreation, changes the microclimate of forest stands, their structure and health condition (Aussenac 2000;Foit 2015;Holuša et al 2021). As a result, the conditions for many species change, of which the insects are the most numerous and vulnerable (Peltonen and Heliövaara 1999;Wermelinger et al 2007).…”

Microclimatic conditions drive summer flight phenology of Platypus cylindrus in managed cork oak stands

“…In consequence, the effect of forest structure in OPB's dynamics deserves more research (e.g. age of the stand, number of dead and weakened trees per hectare, or canopy cover), since it has been found as a relevant factor in other ambrosia and bark beetles (Holuša et al, 2021; Stereńczak et al, 2020).…”

“…56.86%–70.22%; central chart of Figure 4). Wet conditions are considered positive for ambrosia beetles since they rely on fungal growth for developing (Holuša et al, 2021); nevertheless, little is known about the actual effect of humidity in their flight phenology. Interestingly, Nam and Choi (2014) reported lack of captures of P. koryoensis during rainfall episodes although temperature was adequate for adults' flight.…”