Stand-level distribution and movement of Platypus quercivorus adults and patterns of incidence of new infestation

Abstract 1 Flying populations of an ambrosia beetle, Platypus quercivorus (Murayama), a vector of an ambrosia fungus Raffaelea quercivora, which causes deciduous oak diebacks in Japan, were determined by sticky screen traps. 2 Platypus quercivorus beetles tended to move upwards along slopes. The highest concentrations of flying beetles usually occured at the upper forest margins. 3 During the period when the number of flying beetles was increasing, the incidence of newly infested trees spread from the epicentre into the forest. During the period when the number of flying beetles was decreasing, the epicentre shrank into the upper forest edge. Newly infested trees did not occur in this period because most trees had already been infested. 4 Near the upper forest edge, where many beetles were highly concentrated throughout the season, the number of new entry holes decreased greatly after the initial attack early in the season, although many adults were present throughout the period.