Fungal (Sporothrix) induced mortality of kamahi (Weinmannia racemosa) after attack by pinhole borer (Platypus spp.)

The fungus Sporothrix sp. (Deutero-mycotina: Hyphomycetes), was isolated from stained sapwood of recently dead or moribund kamahi (Weinmannia racemosa) which had been attacked by pinhole borer (Platypus gracilis and/or P. apicalis - Coleoptera: Platypodidae). All except one of 10 healthy kamahi inoculated with the isolation died within 16 months, and the remaining tree was debilitated. Control trees inoculated with sterile water remained healthy. The fungus was re-isolated from the dead trees. The symptoms of debility observed in inoculated trees were essentially the same as those in trees from which the inoculum was obtained. Trees less than 30 cm in diameter, with little or no heartwood, died more rapidly than the larger trees. Platypus beetles later attacked all the inoculated trees which showed signs of the moisture stress that is symptomatic of Sporothrix infection. When Platypus attack was induced on six healthy trees, all showed typical symptoms of debility, and five died within four years. Sporothrix was isolated from all the dead trees. Natural Platypus attack was most common in areas of partial or complete canopy collapse. Platypus beetles emerging from wind-thrown, felled, or debilitated kamahi in areas of disturbed forest are therefore likely to kill or damage healthy trees in the vicinity, contributing to more extensive opening of the canopy.