Abstract

Global warming may affect population dynamics of herbivorous insects since the relative impact of bottom-up and top-down processes on herbivore survival is likely to be influenced by temperature. However, little is known about the mechanisms by which warming could affect regulation of populations, particularly when indirect effects across trophic levels are involved. We quantified larval survival of the needle-feeding European pine sawfly, Neodiprion sertifer, either protected from (caged) or exposed to natural enemies at three geographically separated localities in Sweden. The study shows that larval survival is affected by temperature but the direction of the effect is influenced by plant secondary compounds (diterpenes). The results suggest that survival of exposed larvae feeding on needles with high diterpene concentrations will decrease with increasing temperature, while larval survival on low diterpene concentration is less predictable with either no change or an increase with temperature. This food quality dependent response to temperature is probably due to diterpenes having a double-sided effect on larvae; both a negative toxic effect and a positive anti-predator defense effect. Increased temperature had also consequences at the population level; an established population model parameterized using data from the study to evaluate the influence of temperature and plant secondary compounds on the regulation of the sawfly predict that, depending on food quality, outbreak risks could both decrease and increase in a warmer climate. If so, effects of plant secondary compounds will play an increasing role for larval survival in a future warmer climate and temperature will, via multitrophic effects on larval survival, strongly influence how sawfly and other insect populations are regulated.

Keywords

climate change; diterpenes; European pine sawfly; natural enemies; Neodiprion sertifer; plant defense; population dynamics; predation; regulation; Sweden

Published in

Ecosphere
2015, Volume: 6, number: 6
Publisher: ECOLOGICAL SOC AMER

SLU Authors

• Kollberg, Ida

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Bylund, Helena

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Jonsson, Tomas

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Björkman, Christer

  • Department of Ecology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Future Forests
SLU Plant Protection Network


Sustainable Development Goals

SDG13 Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1890/ES15-000021.1

Permanent link to this page (URI)

https://res.slu.se/id/publ/69735