Bionomics ofScolytus schevyrewi(Coleoptera: Curculionidae) in Saskatchewan and Manitoba, Canada

The invasive alienScolytus schevyrewiSemenov (Coleoptera: Curculionidae: Scolytinae) was detected in Saskatchewan and Manitoba, Canada, in 2007. BecauseS. schevyrewiis a potential vector of the Dutch elm disease pathogen (Ophiostomanovo-ulmiBrasier; Fungi: Ophiostomataceae), the natural history of the beetle was studied from 2009 to 2012 in the two provinces, where the disease is managed to protectUlmus americanaLinnaeus (Ulmaceae). Typically, healthy trees become infected when their xylem is contacted during feeding by spore-bearing scolytine adults that have flown from a diseased tree; adults emerging from brood galleries in diseased trees frequently carry spores. We caught flyingS. schevyrewiadults from May to October; adults were weakly attracted to healthyUlmusLinnaeus but were strongly attracted toUlmus pumilaLinnaeus stressed by girdling.Scolytus schevrewicolonised and completed development in girdled trees and trap logs ofU. pumila. In contrast to other studies,U. americana– the major source of pathogen spores in the area – was never colonised as a brood host. Our results suggest thatS. schevyrewiwill primarily useU. pumila, which, in Manitoba and Saskatchewan, seldom exhibits symptoms of Dutch elm disease. Thus, arrival ofS. schevyrewidoes not appear to require changes to Dutch elm disease management programmes.