Peter Hambäck

Peter Hambäck


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Works at Department of Ecology, Environment and Plant Sciences
Telephone 08-16 12 88
Visiting address Svante Arrhenius väg 20 A
Room N 416
Postal address Institutionen för ekologi miljö och botanik 106 91 Stockholm


  • The role of spatial heterogeneity for species interactions, particularly between plants and herbivorous insects.
  • Insect search behaviour, particularly olfactory search.
  • Coevolution in host-parasitoid systems.
  • Ecological immunology.
  • Ecology at water-land interfaces.
  • Spider ecology.
  • Genomic tools for diet analysis

Research projects

  • The ecology and evolution of indirect interactions in host-parasitoid systems. People involved: Xuyue Yang (SU), Ulrich Theopold (SU), Tanja Slotte (SU). Financed through the Swedish Research Council Vetenskapsrådet.
  • Insect responses to spatial heterogeneity. People involved: Thomas Verschut (SU/Univ Groningen), Nora Underwood (Florida State Univ), Brian Inouye (Florida State Univ).
  • Managing constructed and natural wetlands for arthropod diversity in agricultural landscapes. Financed through the Swedish Research Council Formas.
  • Spatially extended food webs: The role of the surrounding landscape for biocontrol in apple orchards. Financed through Carl Tryggers Stiftelse för Vetenskaplig Forskning.

PhD-students (current and previous)


Xuyue Yang, "Coevolution and molecular background of species interactions in geographic mosaics"


Thomas Verschut (main advisor), Dissertation 2017-06-02 on “Searching for food in complex environments: Integrating processes at multiple spatial scales”.

Alma Strandmark (main advisor), Dissertation 2017-06-09, on “Effects of climate induced sea-level changes on coastal ecosystems: plants and arthropods”.

Ulrika Samnegård (coadvisor, main advisor: Kristoffer Hylander), Dissertation 2016-04-01, on "Ecosystem services and disservices on home grown coffee along land-use gradients in Ethiopia: pollination and pest damage"

Lisa Fors, Dissertation 2015-05-08, on “Coevolution in a tritrophic systems: from purple loosestrife to natural enemies"

Lina Lehndal (coadvisor, main advisor: Jon Ågren), Dissertation 2015-05-08, on “Effects of herbivory on population dynamics and evolution of resistance in purple loosestrife (Lythrum salicaria L.)”

Debissa Lemessa (coadvisor, main advisor: Kristoffer Hylander), Dissertation 2014-06-05, on “Pests and pest controlling organisms across tropical agroecological land-scapes in relation to forest and tree cover”.

Petter Andersson (main advisor), Dissertation: 2011-10-27, on “The importance of search behavior for spatial distributions of herbivorous insects”

Gundula Kolb (main advisor), Dissertation: 2010-11-05, on “The impact of cormorant nesting colonies on plants and arthropods“

Kajsa Mellbrand (main advisor), Dissertation: 2009-06-05, on “The Spider and the Sea: Effects of marine subsidies on the role of spiders in terrestrial food webs“

Hannah Östergård (coadvisor, main advisor: Johan Ehrlén), Dissertation: 2008-05-30, on “Plant-seed predator interactions – ecological and evolutionary aspects”

Maria Björkman (coadvisor, main advisor: Birgitta Rämert), Dissertation: 2007-12-13, on “Effects of intercropping on the life cycle of the turnip root fly (Delia floralis)”


A selection from Stockholm University publication database
  • 2017. Thomas A. Verschut (et al.). Scientific Reports 7

    Neighboring resources can affect insect oviposition behavior when the complexity of sensory information obscures information about host resource availability in heterogeneous resource patches. These effects are referred to as associational effects and are hypothesized to occur through constraints in the sensory processing of the insect during host search, resulting into suboptimal resource use. Because the possibilities to study these constraints on naturally occurring animals are limited, we instead used sensory mutants of Drosophila melanogaster to determine the importance of sensory information in the occurrence of associational effects. We found that oviposition was mainly governed by non-volatile chemical cues and less by volatile cues. Moreover, the loss of gustatory sensilla resulted in random resource selection and eliminated associational effects. In conclusion, our study shows that associational effects do not necessarily depend on constraints in the sensory evaluation of resource quality, but may instead be a direct consequence of distinctive selection behavior between different resources at small scales.

  • 2016. Lisa Fors (et al.). Journal of Animal Ecology 85 (6), 1595-1604

    1. Host-parasitoid systems are characterized by a continuous development of new defence strategies in hosts and counter-defence mechanisms in parasitoids. This co-evolutionary arms race makes host-parasitoid systems excellent for understanding trade-offs in host use caused by evolutionary changes in host immune responses and parasitoid virulence. However, knowledge obtained from natural host-parasitoid systems on such trade-offs is still limited.

    2. In this study, the aim was to examine trade-offs in parasitoid virulence in Asecodes parviclava (Hymenoptera: Eulophidae) when attacking three closely related beetles: Galerucella pusilla, Galerucella calmariensis and Galerucella tenella (Coleoptera: Chrysomelidae). A second aim was to examine whether geographic variation in parasitoid infectivity or host immune response could explain differences in parasitism rate between northern and southern sites.

    3. More specifically, we wanted to examine whether the capacity to infect host larvae differed depending on the previous host species of the parasitoids and if such differences were connected to differences in the induction of host immune systems. This was achieved by combining controlled parasitism experiments with cytological studies of infected larvae.

    4. Our results reveal that parasitism success in A. parviclava differs both depending on previous and current host species, with a higher virulence when attacking larvae of the same species as the previous host. Virulence was in general high for parasitoids from G. pusilla and low for parasitoids from G. calmariensis. At the same time, G. pusilla larvae had the strongest immune response and G. calmariensis the weakest. These observations were linked to changes in the larval hemocyte composition, showing changes in cell types important for the encapsulation process in individuals infected by more or less virulent parasitoids.

    5. These findings suggest ongoing evolution in parasitoid virulence and host immune response, making the system a strong candidate for further studies on host race formation and speciation.

  • 2014. Nora Underwood, Brian D. Inouye, Peter A. Hambäck. The Quarterly review of biology 89 (1), 1-19

    Interactions between individual consumer and resource organisms can be modified by neighbors, e.g., when herbivory depends on the identity or diversity of neighboring plants. Effects of neighbors on consumer-resource interactions (associational effects) occur in many systems, including plant-herbivore interactions, predator-prey interactions (mimicry), and plant-pollinator interactions. Unfortunately, we know little about how ecologically or evolutionarily important these effects are because we lack appropriate models and data to determine how neighbor effects on individuals contribute to net interactions at population and community levels. Here we supply a general definition of associational effects, review relevant theory, and suggest strategies for future theoretical and empirical work. We find that mathematical models from a variety of fields suggest that individual-level associational effects will influence population and community dynamics when associational effects create local frequency dependence. However, there is little data on how local frequency dependence in associational effects is generated, or on the form or spatial scale of that frequency dependence. Similarly, existing theory lacks consideration of nonlinear and spatially explicit frequency dependence. We outline an experimental approach for producing data that can be related to models to advance our understanding of how associational effects contribute to population and community processes.

  • 2016. Thomas A. Verschut (et al.). Functional Ecology 30 (11), 1826-1833

    Neighbouring resources have been found to either decrease or increase the likelihood that a consumer organism attacks a focal resource. These phenomena are referred to as associational resistance (AR) and associational susceptibility (AS), respectively. While associational effects have been observed in various field studies, little is known on how resource heterogeneity can cause associational effects. We used a laboratory approach in which we studied the effects of resource density and frequency in the search behaviour of Drosophila melanogaster as a model organism for olfactory-guided behaviour in insects. We first determined whether D.melanogaster could discriminate between odour sources that differ quantitatively. Secondly, we determined what the effect of resource density and frequency was on the search behaviour of D.melanogaster by combining these resources into various patch arrangements. Finally, we used the outcome of our experiments to disentangle the role of resource density and frequency in associational effects. We found that D.melanogaster has the ability to discriminate between quantitatively different resources, but that the attraction to resource density is constrained by an optimum after which attraction decreases. Furthermore, in heterogeneous environments, flies showed a strong preference towards the more apparent resource, leading to AS for the more apparent resources and AR for the less apparent resource. The strength of this interaction increased with a decreasing frequency of the more apparent resource. These results imply that D.melanogaster mainly selects patches at the level of individual resources. Consequently, when a patch contains qualitatively different resources, the more apparent resource will attract a higher number of flies than the less apparent resource irrespective of the frequency of the apparent resource within the patch. Our study shows that associational effects can be explained by determining the hierarchical level at which a consumer selects its resources. When a consumer selects resources at the individual level rather than at the patch level, our results can be used to explain the population dynamics of host plants and their associated consumers under field conditions.

Show all publications by Peter Hambäck at Stockholm University

Last updated: December 14, 2018

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