Evidence of interaction betweenSirex noctilioand other species inhabiting the bole ofPinus

Abstract

Sirex noctiliois a woodwasp native to Eurasia and Northern Africa and has recently been found infesting pines in eastern North America. Its pest status in this new range is not yet known, although it is an important pest in other areas where it has been introduced.Pinusspp. in North America are hosts to several native and alien species of subcortical insects. Interactions between the woodwasp and these species may influence its distribution or the characteristics of its life history, thus affecting its population dynamics over time.SixtyS. noctilio‐infestedPinusspp. were felled in Ontario, Canada, and all phloem‐feeding and woodboring insects were collected and identified from each 1‐m section of the tree.Sirex noctiliowas in a tree alone 10% of the time but commonly shared the tree with subcortical beetles, such asTomicus piniperda,Pissodes nemorensis,Ips grandicollis,Gnathotrichus materiariusandMonochamus carolinensis. The woodwasp was distributed throughout the tree stem and this distribution overlapped with that of the beetles.Fewer but largerS. noctiliomales emerged from trees with beetles compared with those without, although there was no statistical difference in females.These findings suggest that co‐habiting beetles could negatively affectS. noctiliopopulation dynamics over time. The potential mechanisms for this interaction are discussed.