Competition Between Two Biological Control Agents, Neurostrota gunniella and Phloeospora mimosae-pigrae , and Their Impact on the Invasive Tropical Shrub Mimosa pigra

Abstract

The impact of a stem-boring moth Neurostrota gunniella and a fungal plant pathogen Phloeospora mimosae-pigrae on Mimosa pigra seedlings was investigated in a shade house. N. gunniella and P. mimosae-pigrae , either alone or in combination, reduced seedling growth by approximately 29-38% which, in field conditions, should be associated with reduced survivorship during wet-season flooding. There was no significant difference in N. gunniella damage between plants inoculated with N. gunniella alone, and plants inoculated with both N. gunniella and P. mimosae-pigrae . However, pathogen symptoms were significantly greater on plants inoculated with P. mimosae-pigrae alone than when N. gunniella was also present. Competition between N. gunniella and P.mimosae-pigrae may be at least partially responsible for the current poor performance of P. mimosae-pigrae in Australia.