My team previously used four approaches to quantify the effects of climate change on insect-plant interactions. First, we analysed the results of long-term monitoring (lasting 22–32 years) of forest moths and leaf beetles conducted in subarctic regions of Finland and Russia. Second, we used latitudinal gradients in Northern Europe as natural laboratories to infer responses of background insect herbivory to temperature. Third, we used passive greenhouse chambers to study the impacts of elevated temperatures on insect-plant interactions under field conditions. Fourth, we used meta-analysis to infer general patterns in the effects of experimental elevation of both CO2 and temperature on plant-feeding insects and their host plants, and we used published (historical) data to identify past changes in background losses of woody plant foliage to insects.
We are currently monitoring the belowground herbivory along a latitudinal gradient in Northern Europe and collecting data for a meta-analysis of the effects of abiotic drivers of global change on fine root production and on root quality as a resource for root-feeding insects. We are also monitoring the intensity of parasitism and predation of leaf-feeding insects along this latitudinal gradient and experimentally exploring the effects of ambient temperatures on the feeding niche breadth and adult behaviour of the polymorphic leaf beetle, Chrysomela lapponica.
Kozlov, M. V. & Zvereva, E. L. (2015). Changes in the background losses of woody plant foliage to insects during the past 60 years: are the predictions fulfilled? Biology Letters, 11, 20150480 (doi: 10.1098/rsbl.2015.0480).
The prevailing scenarios predict that herbivory will increase with climate warming. However, analysis of the published data on the background foliar losses of woody plants to insects in natural ecosystems across the globe from 1952 to 2013 provided no support for this hypothesis. We detected no temporal trend in herbivory within the temperate climate zone and a significant decrease in herbivory in the tropics.
Zvereva, E. L., Hunter, M. D., Zverev, V. & Kozlov, M. V. (2016) Factors affecting population dynamics of leaf beetles in a subarctic region: the interplay between climate warming and pollution decline. Science of the Total Environment 566-567, 1277–1288 (doi: 10.1016/j.scitotenv.2016.05.187).
We explored how simultaneous changes in climate and pollution affect population dynamics of plant-feeding insects. In spite of 3 °C warming from 1993 to 2014, we did not observe an increase in abundance in any of four monitored leaf beetle species. Moreover, densities of two species declined 20-fold with fivefold decrease in emissions due to increase in mortality from natural enemies. This pattern suggests that at least in some tri-trophic systems, top-down factors override bottom-up effects and govern the impacts of environmental changes on insect herbivores.
Kozlov, M. V., Stekolshchikov, A. V., Söderman, G., Labina, E. S., Zverev, V. & Zvereva, E. L. (2015) Sap-feeding insects on forest trees along latitudinal gradients in northern Europe: a climate-driven pattern. Global Change Biology, 21, 106–116 (doi: 10.1111/gcb.12682).
We developed and employed the new method to evaluate background losses of forest trees to sap-feeding insects and found that in boreal forests these losses are of the same order of magnitude as losses to defoliators. Plant losses to sap-feeders demonstrated hump-shaped relationships with mid-summer temperatures, indicating that climate warming may have different consequences for background insect herbivory in different climate zones.
Hunter, M. D., Kozlov, M. V., Itämies, J., Pulliainen, E., Bäck, J., Kyrö, E.-M. & Niemelä, P. (2014) Current temporal trends in moth abundance are counter to predicted effects of climate change in an assemblage of subarctic forest moths. Global Change Biology, 20, 1723-1737 (doi: 10.1111/gcb.12529).
We examined population dynamics of subarctic forest moths in Finnish Lapland based on light trapping that was made continuously over a period of 32 years. Temperature and winter precipitation at our study site increased rapidly during the sampling period. The per capita rates of change of moth species’ abundance were more frequently associated negatively than positively with climate change variables. Nonetheless, subarctic forest moths are performing better than expected, suggesting that their populations are buffered at present from potential deleterious effects of climate change by other ecological forces.
M. D. Hunter
E. J. van Nieukerken
P. W. Price