Outbreak dynamics of the woodwasp Sirex noctilio: unravelling drivers that may help improve pest management inpine plantations

CORLEY, JUAN C; LANTSCHNER, MARÍA VICTORIA; VILLACIDE, JOSÉ M

Thessaloniki

Congreso; IUFRO Joint Meeting of working parties 7.03.05 y 7.03.10 ?Forest Insects and Pathogens in a Changing Environment: Ecology, Monitoring & Genetics?; 2017

Insect outbreaks are a most important natural disturbance in forest systems that can cause immense economic and ecological impact. The woodwasp Sirex noctilio is a major invasive pest of commercial pine plantations, known for displaying a pulse-like eruptive population behaviour. It is during outbreaks when damage becomes economically significant. Here we bring together studies on the population ecology of S. noctilio, carried out in Argentina with the aim of contributing to identify process underlying the observed outbreaks. In a region wide study, we noted that there was a marked spatial synchrony in outbreak occurrence, and that drought events may be an important broad-scale synchronizing factor. We also found at a smaller spatial scale, the spatial arrangement of pine stands bearing outbreaks was mainly influenced by the pine tree species present, slope aspect, and distance to other outbreaks. In turn, at a stand scale, we can recognize a strong aggregation of attacked trees in stands with growing infestation levels. Here, the degree of attacks is influenced by host tree species and management. Through our models, we show that outbreaks may be the result of the insect's life history, since aggregated attack-led by coupled short and long distance female dispersal may create the conditions for eruptive dynamics. Our main message is that S. noctilio outbreaks are, as expected, the consequence of multiple factors yet we can identify some that maybe subjected to management and likely contribute to reduce potential losses caused by this serious pine pest.