Biology and management of bark beetles (Coleoptera: Curculionidae) in Washington cherry orchards

The biology and management of bark beetles (Coleoptera: Curculionidae, Scolytinae) in Washington cherry orchards was investigated from 2003-2005. Two dominant species were identified attacking cherry (Prunus spp.) orchards: the shothole borer, Scolylus rugulosus Muller, and an ambrosia beetle, Xyleborinus saxeseni Ratzeburg. S. rugulosus was the species most implicated in damage to healthy trees. Two distinct periods of S. rugulosus activity occur in Washington, with a possible partial third in some locations. The first activity period begins in late April and peaks in late May to early June, with the second beginning in mid-July and peaks in late July to early August. Yellow sticky traps (unbaited apple maggot traps) were effective tools to monitor S. rugulosus activity but ethanol-baited intercept-style traps were necessary to monitor X saxeseni activity. Movement of S. rugulosus into orchards was closely associated with emergence from outside hosts, generally a pile of recently pruned or cut wood placed outside the orchard. S. rugulosus readily moved distances of 10-50 m to attack trees on orchard borders, but did not move more than two or three rows into a healthy orchard. A residue bioassay technique demonstrated that several insecticides caused mortality of S. rugulosus adults. A pyrethroid, esfenvalerate, was the most active 21 d after treatment. Azinphos-methyl was acutely toxic to S. rugulosus, but for only seven d. Endosulfan and the neonicotinyls, thiamethoxam and acetamiprid, were somewhat toxic to S. rugulosus.