Assessing mass trapping efficiency and population density of Cerambyx welensii Küster by mark-recapture in dehesa open woodlands

Abstract

A severe oak decline is taking place across the Mediterranean region since the 1980s. Among the climatic and biological factors involved in this complex syndrome, the longhorn C. welensii is currently considered a major element. Furthermore, larval damage to young or healthy trees is being increasingly important and thereby also the need to manage this emerging pest species. This paper deals with quantifying the adult populations in the field in order to evaluate the potential performance of mass trapping as control method against C. welensii. We used a mark-recapture protocol using feeding traps, which was complemented with some nocturnal observations and additional laboratory studies. Research was conducted in the Cornalvo Natural Park (southwestern Spain) during two consecutive years (2008–2009). Data were analysed with classic closed population (CP) methods and Maximum Likelihood Spatially Explicit Capture-Recapture (ML SECR) detection models. The results strongly supported the potential success of mass trapping as control method for C. welensii, including a high trapping efficiency (70–81%), relatively low adult population density for a pest species (316 and 265 adults/ha in 2008 and 2009), movement pattern of flying adults and highly aggregated distribution of adults in trees with traps. We also found experimental evidence that most adults come to the traps close to emergence as showed body appearance, longevity estimates and female reproductive age at trapping time. We discuss the practical achievement of mass trapping as control method integrating behavioural and ecological perspectives and, though a large-scale field validation is still lacking, we conclude that mass trapping may be a potential tool to manage C. welensii populations in dehesa open woodlands.