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The northern bark beetle (Ips duplicatus), in Europe originally restricted to northern countries, expanded its distribution range to eastern Europe in the 20th century and is now causing considerable damage in spruce forests. In the past decades its presence has been confirmed in several Central European countries. By means of pheromone traps and visual inspection of infested logs, in this study we demonstrate that I. duplicatus is also present in the Rhine valley in Switzerland and Liechtenstein. Breeding galleries with beetles and exit holes in an infested spruce log indicate that the trapped beetles had successfully developed in a local stand nearby. An inquiry addressed to European entomologists was carried out to obtain information and references concerning the year of the first record or mention of I. duplicatus in their respective countries. This information substantiated the expansion of its historical range to the southeast in the middle of the last century and clearly showed recent movement westward, with Switzerland and Germany currently the westernmost countries where this species occurs. This recent range expansion is likely attributed to the transport of infested timber. The economic significance of this expanding bark beetle species is discussed in view of its co-occurrence with the notorious pest species I. typographus.

The Asian longhorned beetle Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) is one of the most dangerous xylophagous pests affecting broadleaf trees in the world. Eradication programmes are undertaken in non-native regions, requiring extensive resources and involving high costs. An adapted strategy must be set up to optimize the ratio cost/probability of success. We developed a method to generate a risk index of A. glabripennis presence at a local scale, in the surrounding area of an infestation, using field observations (counts of adult insects, exit holes and infested trees). The method, mathematically based on the bivariate symmetric Laplace distribution, has thus reasonable input requirements. The output risk map is easy to interpret and can be directly used by decision-makers. We used our approach in three infestations in Switzerland. The risk map represented well the insect pressure (beetle population density). We highlighted the fact that survey boundaries, commonly chosen using constant distances from the infestation, should be selected regarding the spatial distribution of the insect pressure, to prioritize monitoring activities. The risk map provides a helpful instrument for advanced survey planning after a first overview, for example to decide which area and which host trees should be inspected for infestations.

Bark beetles are among the most devastating biotic agents affecting forests globally and several species are expected to be favored by climate change. Given the potential interactions of insect outbreaks with other biotic and abiotic disturbances, and the potentially strong impact of changing disturbance regimes on forest resources, investigating climatic drivers of destructive bark beetle outbreaks is of paramount importance. We analyzed 17 time-series of the amount of wood damaged by Ips typographus, the most destructive pest of Norway spruce forests, collected across 8 European countries in the last three decades. We aimed to quantify the relative importance of key climate drivers in explaining timber loss dynamics, also testing for possible synergistic effects. Local outbreaks shared the same drivers, including increasing summer rainfall deficit and warm temperatures. Large availability of storm-felled trees in the previous year was also strongly related to an increase in timber loss, likely by providing an alternative source of breeding material. We did not find any positive synergy among outbreak drivers. On the contrary, the occurrence of large storms reduced the positive effect of warming temperatures and rainfall deficit. The large surplus of breeding material likely boosted I. typographus population size above the density threshold required to colonize and kill healthy trees irrespective of other climate triggers. Importantly, we found strong negative density dependence in I. typographus that may provide a mechanism for population decline after population eruptions. Generality in the effects of complex climatic events across different geographical areas suggests that the large-scale drivers can be used as early warning indicators of increasing local outbreak probability., SCOPUS: ar.j, info:eu-repo/semantics/published

The predicted increase in temperature, dry summers, and extreme meteorological events will affect many harmful species both by directly accelerating their propagation rates as well as by weakening their host plants. There might also be shifts in the interrelations in species communities that can hardly be predicted. Some fungal species, that had previously been inconspicuous, caused notable damages in the drought periods of the last two decades. Higher winter temperatures often increase the survival rates of many fungal and insect species. Because hot and dry summers are likely to become more frequent and heavy storms tend to occur more often, an increase in massive outbreaks of bark beetles with corresponding damage is to be expected. As a result of global trade, more invasive alien fungi and insects are introduced into Europe where the climatic conditions become more favorable for them to establish themselves on native or introduced host trees. Insects and diseases can have a profound impact on forest dynamics. Therefore, these disturbances must be included in the discussion of future tree species composition and of forest development scenarios.

Cerambicidi invasivi provenienti dall’Asia: Ecologia e gestione

In the dry Swiss Rhone Valley, Scots pine forests have experienced increased mortality in recent years. It has commonly been assumed that drought events and bark beetles fostered the decline, however, whether bark beetle outbreaks increased in recent years and whether they can be linked to drought stress or increasing temperature has never been studied.In our study, we correlated time series of drought indices from long-term climate stations, 11-year mortality trends from a long-term research plot, and mortality probabilities modeled from tree rings (as an indicator of tree vitality) with documented occurrences of various bark beetle species and a buprestid beetle, using regional Forest Service reports from 1902 to 2003 and advisory cases of the Swiss Forest Protection Service (SFPS) from 1984 to 2005. We compared the historical findings with measured beetle emergence from a 4-year tree felling and breeding chamber experiment.The documented beetle-related pine mortality cases increased dramatically in the 1990s, both in the forest reports and the advisory cases. The incidents of beetle-related pine mortality correlated positively with spring and summer temperature, and with the tree-ring-based mortality index, but not with the drought index. The number of advisory cases, on the other hand, correlated slightly with summer drought index and temperature, but very highly with tree-ring–based mortality index. The tree-ring-based mortality index and observed tree mortality increased in years following drought. This was confirmed by the beetle emergences from felled trees. Following dry summers, more than twice as many trees were colonized by beetles than following wet summers.We conclude that increased temperatures in the Swiss Rhone Valley have likely weakened Scots pines and favored phloeophagous beetle population growth. Beetles contributed to the increased pine mortality following summer drought. Among the factors not addressed in this study, changed forest use may have also contributed to increased beetle populations and Scots pine mortality, whereas air pollution seems to be of lesser importance.

Using an extensive dataset from the Canton Berne spatial patterns were analysed of the first Ips typographus- infestations of standing trees after the storm Lothar on December 1999. Our results suggest that these first infesta- tions were not caused by bark beetles indiscriminately spreading out of windthrow areas. Rather, we found rela- tionships between levels of attacked standing trees and cleaned, scattered windthrown trees. We therefore conclude that our results point to reduced host tree resistance as a key factor. Abstract: Ein umfangreiches Datenmaterial aus dem Kanton Bern erlaubte die Analyse des raumlichen Verteilungsmusters des ersten Stehendbefalls durch den Buchdrucker Ips typo- graphus, der als Folge des Sturmes Lothar entstand. Unsere Resultate deuten darauf hin, dass der erste Befall stehender Baume nicht massgeblich durch eine ungerichtete Dispersion der Kafer aus den Windwurfflachen hervorgerufen wurde. Hingegen fanden wir raumliche Beziehungen zwischen dem Stehendbefall und geraumten Sturm-Streuschaden im Rest- bestand. Wir gehen deshalb davon aus, dass unsere Resultate eine reduzierte Widerstandskraft der Restbestande als Schlusselfaktor anzeigen.

In early 2002, startling changes of colour appeared on the leaves and needles of evergreen tree species at higher altitudes. The trees formed «red belts» across the mountain slopes, several hundred meters long. The discolouration was caused by frost in the previous winter. In this paper we present the reaction of conifers to frost and look at the most important occurrences of frost in the last decades. Based on experience gained following the widespread frosts of 1986/1987, we can expect most of the damaged trees to recover over the next few years. This expectation, however, will only be fulfilled if there are no subsequent and serious bark beetle attacks. Continued surveillance of the injured forest sites is, therefore, necessary.

Pine processionary moth, Thaumetopea pityocampa, is a model insect indicator of global warming, the northwards and upwards range expansion of this Mediterranean species being directly associated with the recent warming up. The knowledge about the drivers of moth expansion is synthesized. A first standardized mapping of the northern expansion edge, from Western Europe to Turkey, is presented, then detailed for 20 countries of Europe, Asia Minor and North Africa, including future trends. Additional data about the responses of the other Thaumetopoea species are given. Finally, the chapter points out the importance of the man-mediated introductions in the expansion process. © Éditions Quæ, 2015.