Sub-cortical interactions between Monochamus titillator and Ips grandicollis in a laboratory setting: does arrival time affect survival?

Species that exploit the same resource in a similar manner belong to feeding guilds and can be subject to intraguild interactions.  These intraguild interactions can include competition or predation and can be increased by species coexisting in space and time.  In the southeastern U.S. Monochamus titillator and Ips grandicollis have multivoltine generations that share nutritional resources, living space, and similar phenologies while proceeding through larval development.  This considerable overlap within their host pines makes intraguild interactions highly likely.  While interactions between Monochamus species and other members of the same guild in southeastern pine forests have been previously demonstrated, no studies have shown the same interactions for M. titillator and I. grandicollis.  Our objectives are to (1) determine if M. titillator colonization of I. grandicollis colonized shortleaf pine affects survival of I. grandicollis, and (2) determine if the time between I. grandicollis colonization and subsequent M. titillator colonization affects I. grandicollis survival.

To determine the effect of M. titillator colonization on I. grandicollis survival a controlled laboratory study was done using shortleaf pine bolts infested with 30 I. grandicollis.  These bolts were then exposed to either two or five mated female M. titillator.  M. titillator introduction occurred on the same day, three days after, or six days after I. grandicollis introduction. Results demonstrate that M. titillator colonization leads to sub-cortical interaction which diminishes I. grandicollis survival.