COMPETITION BETWEEN FUNGI ASSOCIATED WITH WOODWASP AND SOUTHERN BEETLE K.D. Klepzig1, M.J. Wingfield2, and B. Slippers2 1U.S. Forest Service, Southern Research Station 2500 Shreveport Hwy., Pineville, LA 71360 2Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002 ABSTRACT

The mutualistic symbiotic of the invasive The area colonized by each competing fungus was woodwasp Sirex noctilio is areolatum, a measured as an indicator of its ability to colonize (and wood rotting fungus. Wood rotted by A. areolatum is fed defend) substrate. The primary phoretic associate of SPB upon by developing woodwasp larvae. The fungus itself was able to competitively exclude the mutualistic fungus serves as the food source for Deladenus siricidicola, a of the and vice versa. The success of that also parasitizes Sirex larvae. The resulting SPB or Sirex associated fungi will thus likely depend sterilization of adult woodwasps serves as the basis upon order of arrival. The likely influences on success of for biological control programs worldwide. Biological Sirex biocontrol efforts may then include the following: control of S. noctilio is achieved via the use of trap logs, 1. Timing of inoculation/ placement of trap trees colonized by feeding upon A. areolatum. Any —A. areolatum will need to be well established before interference with these linked life cycles may disrupt the exposure to vectoring stain fungi. biological control system and corresponding reductions 2. Variability within strains of A. areolatum and in S. noctilio populations. parasitic nematodes—Substantial variation exists in We tested competitive interactions between A. areolatum competitiveness of A. areolatum strains and in their and the southern pine beetle (SPB) fungal associates it compatibility with biocontrol nematodes. may interact with if it becomes established in the U.S. 3. Abundance of, and pressure from, indigenous pine South. (from South Africa), colonizing beetles and their associated fungi—Seasonal Ophiostoma minus, Ceratocystiopsis ranaculosus, and and dynamical factors may influence pressure from Entomocorticium sp. A (all from SPB in the U.S.) were competitors for log substrates. pitted against one another on malt agar.

2008 USDA Research Forum on Invasive 39