Modelling the potential impact of global warming on Ips typographus voltinism and reproductive diapause

Abstract

The Eurasian spruce bark beetle, Ips typographus, is one of the major forest insect pests in Europe, capable of mass-attacking and killing mature Norway spruce trees. The initiation and development of a new generation are strongly controlled by temperature and a warmer climate may affect the number of generations that is produced per year and hence the outbreak dynamics. Experimental knowledge regarding reproductive diapause adaptations is, however, too sparse for largescale assessments of future trends. We developed a model description of diapause induction, and used gridded observational temperature data to evaluate multiple combinations of day length and temperature thresholds to find the model parameterisation most coherent with I. typographus monitoring data from Scandinavia. The selected model parameterisation is supported by European literature data, though further experimental studies are required to analyse population specific adaptations and capacity for adjustments to changing climate conditions. Implementing the 696 Climatic Change (2011) 109:695-718 model description of reproductive diapause in a temperature driven model of bark beetle phenology (swarming activity and development from egg to mature bark beetle), enabled us to assess the length of the late summer swarming period that is a critical determinant of the risk of forest damage. By using regional climate model data we show that higher temperatures can result in increased frequency and length of late summer swarming events, producing a second generation in southern Scandinavia and a third generation in lowland parts of central Europe. Reproductive diapause will not prevent the occurrence of an additional generation per year, but the day length cues may restrict the length of the late summer swarming period.

Climate drivers of bark beetle outbreak dynamics in Norway spruce forests

“…Temperature is the most important determinant of developmental time and voltinism of I. typographus (Annila 1969, Wermelinger and Seifert 1998, Jönsson et al 2011. Warm spring and summer temperatures support an earlier completion of the first filial generation and the establishment of sister and successive generation broods (Wermelinger and Seifert 1998).…”

Using UAV-Based Photogrammetry and Hyperspectral Imaging for Mapping Bark Beetle Damage at Tree-Level

“…According to the projections of climatic change impacts, distribution of forest pest insects, as well as insect-induced damage will gradually shift towards northern latitudes. This climate-driven phenomenon has already been evident with pine sawflies [2,3], moths [4,5] and bark beetles [6,7]. Rapidly increasing forest disturbances give rise to a threat for forest health and substantial economic losses [8].…”

Composition and Elevation of Spruce Forests Affect Susceptibility to Bark Beetle Attacks: Implications for Forest Management

“…Many studies on the population dynamics of bark beetles suggest that climatic anomalies, such as drought and heat waves, may trigger large insect outbreaks [8][9][10], acting both directly on the insect populations and indirectly on the health of the potential host trees. In the last few years, the spruce bark beetle, Ips typographus (L.), one of the most destructive insects infesting spruce forests (Picea abies Karsten), caused serious damage almost everywhere in Europe [3,[11][12][13]. Severe damage was also recorded in spruce forests growing on the Southern Alps [14][15][16][17][18][19].…”