Mega-trap-plots: a novel method of Sirex woodwasp management on Pinus radiata plantations in Chile

Abstract

Sirex noctilio is one of the most important invasive pests that affect Pinus radiata plantations in Chile. Its management is based on a biological control complex, the most important component of which is the nematode, Deladenus siricidicola. However, in some areas, S. noctilio populations attain epidemic levels and no effective control methods exist to reduce large populations in a short period. In this study, we evaluated a novel method called mega-trapplots (MTPs), which consist of an area of 1 ha with trap trees, which were debilitated in four different months (from November to February) with the purpose of reducing the Sirex wasp population through harvesting of trees attacked. The main objective was to reduce the potential population of S. noctilio, by evaluating four periods or months of MTP installation to maximise the colonisation of trap trees by wood wasps. The results showed that the MTPs that were installed from November to January had the highest wood wasp infestation, which was coincident with the flight period of the insect. The trap trees were clearly attractive to S. noctilio females up to 90 d following their establishment. The MTPs that were established in November concentrated a potential population of 57 901 females of S. noctilio, which represents a population 5.4 times greater than that in the control, with 10 701 females. The population of S. noctilio attracted between November and January shows that the use of MTPs is an effective system for the management of wood wasps on plantations with a high level of infestation and thereby can reduce their spread and the attack of new trees within the same forest compartments.

Keywords: mega-trap-plot, radiata pine plantations, Sirex control, Sirex wood wasp, trap tree