Spatio‐temporal impact of climate change on the activity and voltinism of the spruce bark beetle, Ips typographus

Abstract

The spruce bark beetle Ips typographus is one of the major insect pests of mature Norway spruce forests. In this study, a model describing the temperature-dependent thresholds for swarming activity and temperature requirement for development from egg to adult was driven by transient regional climate scenario data for Sweden, covering the period of 1961-2100 for three future climate change scenarios (SRES A2, A1B and B2). During the 20th century, the weather supported the production of one bark beetle generation per year, except in the north-western mountainous parts of Sweden where the climate conditions were too harsh. A warmer climate may sustain a viable population also in the mountainous part; however, the distributional range of I. typographus may be restricted by the migration speed of Norway spruce. Modelling suggests that an earlier timing of spring swarming and fulfilled development of the first generation will significantly increase the frequency of summer swarming. Model calculations suggest that the spruce bark beetle will be able to initiate a second generation in South Sweden during 50% of the years around the mid century. By the end of the century, when temperatures during the bark beetle activity period are projected to have increased by 2.4-3.8 1C, a second generation will be initiated in South Sweden in 63-81% of the years. The corresponding figures are 16-33% for Mid Sweden, and 1-6% for North Sweden. During the next decades, one to two generations per year are predicted in response to temperature, and the northern distribution limit for the second generation will vary. Our study addresses questions applicable to sustainable forest management, suggesting that adequate countermeasures require monitoring of regional differences in timing of swarming and development of I. typographus, and planning of control operations during summer periods with large populations of bark beetles.

Seasonal flight patterns of Ips typographus in southern Sweden and thermal sums required for emergence

“…Nonetheless, our study showed that the thermal conditions in southern Sweden during each of the study years would have allowed the development of a second generation. This is in accordance with calculations by Jönsson et al (2009), which indicated that even with the current climate; a fully developed second generation can be expected in some years each decade. With global warming, we can expect a second generation of I. typographus to occur more frequently in Fennoscandia (Lange et al, 2006;Schlyter et al, 2006;Jönsson et al, 2007Jönsson et al, , 2009.…”

“…This is in accordance with calculations by Jönsson et al (2009), which indicated that even with the current climate; a fully developed second generation can be expected in some years each decade. With global warming, we can expect a second generation of I. typographus to occur more frequently in Fennoscandia (Lange et al, 2006;Schlyter et al, 2006;Jönsson et al, 2007Jönsson et al, , 2009. The thermal sums that we have presented here could be used to improve parameterization of simulation models in southern Sweden, since they are both more region specific and based on a higher number of replicates of localities and years than previous data sets that had been used for simulations of bark beetle population dynamics in this region (Harding and Ravn, 1985;Jönsson et al 2007Jönsson et al , 2011.…”

“…However, thermal sums for when first flight occurs have been calculated in earlier studies (Annila, 1969;Baier et al, 2007;Jönsson et al, 2007Jönsson et al, , 2009, our results show closer correlation with those figures when a combination of flight threshold and a thermal sum is used, i.e. the first day with a maximum temperature exceeding 16°C after the mean thermal sum at first flight has been exceeded (47 dd).…”

Toward a synthetic understanding of the role of phenology in ecology and evolution

“…In short-lived species, warmer temperatures and longer growing seasons may allow additional generations per year (e.g. Tobin et al 2008;Jö nsson et al 2009;Altermatt 2010). Both of these possibilities have major implications for population growth.…”

Modelling natural disturbances in forest ecosystems: a review

“…models of insect life cycle events) employ species-and life stage-specific temperature requirements towards a more process-based representation of an insect's climate dependency (Gaylord et al, 2008). Such approaches have been developed for important insect pest species, such as Ips typographus (L.) (Wermelinger and Seifert, 1998;Netherer and Pennerstorfer, 2001;Netherer and Nopp-Mayr, 2005;Baier et al, 2007: PHENIPS;Jönsson et al, 2007Jönsson et al, , 2009 and Lymantria dispar (L.) (Logan and Bentz, 1999;Gray, 2004;Powell and Logan, 2005;Pitt et al, 2007). Incorporating species-specific diapause regulation into such models was found crucial for predicting the response to driving climate variables (Gray et al, 2001;Steinbauer et al, 2004;Dolezal and Sehnal, 2007;Tobin et al, 2008).…”