Elevated atmospheric carbon dioxide concentrations alter root morphology and reduce the effectiveness of entomopathogenic nematodes

  • Ivan HiltpoldEmail author
  • Ben D. Moore
  • Scott N. Johnson
Regular Article



The effects of increasing atmospheric carbon dioxide (CO2) concentrations on beneficial soil fauna, such as entomopathogenic nematodes (EPNs), are poorly understood. We hence aimed to characterize how elevated CO2 (eCO2) affects maize plant (Zea mays) growth, root morphology and the effectiveness of the EPN Heterorhabditis bacteriophora.


We grew plants under ambient CO2 (aCO2; 400 μmol mol-1) and eCO2 (640 μmol mol-1) and quantified shoot growth and six root traits. We simultaneously quantified the effectiveness of EPNs (mortality of insect hosts (Galleria mellonella) and EPN density within hosts) when foraging in planted and plant-free environments. Structural equation modeling (SEM) was used to model direct and indirect relationships between atmospheric CO2, root morphology and EPN effectiveness.


Root systems of plants grown under eCO2 grew faster, longer, denser, and larger than plants grown under aCO2. This in turn reduced EPN effectiveness as, despite no significant difference between aCO2 and eCO2 in host mortality, significantly more nematodes were recovered from hosts in the vicinity of plants grown in aCO2 environment. The SEM model revealed that this impact was indirect and mediated by the increased root morphological traits.


We provide the first example of how changes in atmospheric CO2 indirectly reduce the effectiveness of an EPN used globally for crop protection. Other factors (e.g. plant volatile emissions) may moderate or exacerbate these patterns but our findings suggest that modifications in root traits at eCO2 negatively impact EPN effectiveness and therefore soil-dwelling insect pest management.


Soil microbiome Climate change Root morphology Root herbivore Pest control 



Entomopathogenic nematode


Ambient carbon dioxide (400 μmol mol−1)


Elevated carbon dioxide (640 μmol mol−1)


Carbon dioxide


Structural equation modeling



We thank Abisha Srikumar for her support in this project. She was funded by a Summer Student Award from the Hawkesbury Institute for the Environment. This research was funded by the Australian Research Council project DP14100363 awarded to SNJ and BDM

Supplementary material

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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Hawkesburry Institute for the EnvironmentWestern Sydney UniversityRichmondAustralia
  2. 2.Department of Entomology and Wildlife Ecology, College of Agriculture and Natural ResourcesUniversity of DelawareNewarkUSA

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