Long-Term Assessment of Selective Pruning of Quercus Species for Controlling Populations of Coraebus florentinus (Coleoptera: Buprestidae) in Mediterranean Forests

Abstract

Coraebus florentinus (Herbst) is one of the most important wood borer pests damaging oak species in Mediterranean forests. Recently, the effect of temperature on the pre-imaginal development of this insect was established, and predictive models of survival and emergence in relation to temperature were performed, which allow scheduled management techniques to be fit in accordance with the biological timing of this species. In this study, the effect of selective pruning of damaged branches of Quercus species for controlling the population of this insect is assessed. The study was carried out in three plots located in the Sierra Morena Mountains (southern Iberian Peninsula). In each plot, forest features were typified, and the parameters "infestation level" and "population intensity" were quantified. The assessment was performed one year and five years after applying selective pruning. The most effective time to prune was established according to the predictive model mentioned above. After one year, the results indicated that selective pruning just before adult emergence was effective in reducing the population size and controlling damage. After five years, this effect was still significantly manifested. In addition, the results show that selective pruning is effective even in areas with lower initial rates of infestation.

Assessment and Monitoring Damage by <i>Coraebus florentinus</i> (Coleoptera: Buprestidae) in Mediterranean Oak Forests

“…In conclusion, based on the current results and those of prior research, it can be stated that there has been a local thermal increase that has affected the populations of C. florentinus in the southern Iberian Peninsula, extending their damage but not intensifying them significantly. The foreseeable spreading of the insect on the future climate scenarios makes necessary the implementation of effective control activities, as selective pruning [6], in the management of Mediterranean oak forests, as a preventive measure to avoid the demographic explosion of this pest.…”

“…To assess damage by C. florentinus, the following parameters were estimated [6] [ Differences in tree density between P1 and P2 were tested but considering the overall sample. On this case, the statistical test did not found significant differences (T = −0.671, P = 0.515).…”

“…florentinus is a xylophagous jewel beetle (Coleoptera: Buprestidae), which bores the branches of different species of Quercus [5]. Because of its affinity by holm (Quercus ilex, Linné 1753) and cork oaks (Q. suber, Linné 1753), this insect is mainly distributed in the Mediterranean forests where these tree species predominate [6].…”

“…In several countries from the Mediterranean basin (Italy, Spain and Portugal) it has been detected that populations of the buprestid are growing at the same time that the damages they produce are increasing [8]. These processes are linked, in addition to other factors, to the progressive abandonment of pruning in the Mediterranean oak forests [13], in spite of being the most effective control method for some pests like this case [6] [14].…”

Mapping oak shoot browning in SW Spain using online imagery as virtual prospecting tool

“…A higher incidence of shoot browning in warmer parts of the treetop and sun-exposed oak stands is consistent with previous reports on the well-known heliophilic and thermophilic behaviour of C. florentinus Gallardo 2012, 2013;Soria and Ocete 1993), but also with the thermophilic nature of Diplodia species infecting oaks (Luque 1989). In the case of C. florentinus, thermophily explains why temperature rise derived from global warming has triggered the increase in damage reported in last years in France (Sallé et al 2014) and Spain (Gallardo et al 2018), and also why the beetle has expanded, since 1980, their septentrional distribution range towards northern France and southwestern Germany (Buse et al 2013). Regarding the fungus, we found a similar scenario as oak-infesting Diplodia species exhibit an optimal growth at relatively high temperatures (25-28°C and even higher) (Luque 1989;Muñoz López et al 1992) for which they are also scored as thermophilic or thermotolerant (Panzavolta et al 2017).…”