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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Publications at this Location » Publication #342105
Title: Influence of drought on plant performance through changes in belowground tritrophic interactions

Author
item GUYER, ANOUK - University Of Bern
item Hibbard, Bruce
item HOLZKAMPER, ANNELIE - Agroscope
item ERB, MATTHIAS - University Of Bern
item ROBERT, CHRISTELLE - University Of Bern

Submitted to: Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2018
Publication Date: 7/21/2018
Publication URL: https://handle.nal.usda.gov/10113/6472377
Citation: Guyer, A., Hibbard, B.E., Holzkamper, A., Erb, M., Robert, C.A. 2018. Influence of drought on plant performance through changes in belowground tritrophic interactions. Ecology and Evolution. 8:6756-6765. http://doi.org/10.1002/ece3.4183.
DOI: https://doi.org/10.1002/ece3.4183

Interpretive Summary: The western corn rootworm is the most economically damaging pest of corn in the United States, yet many aspects of its basic biology remain understudied. We investigated the effects of soil moisture on the interaction between maize, the western corn rootworm, and soil-borne natural enemies and other biocontrol agents of western corn rootworm. In a manipulative field experiment, decreasing soil moisture as well as rootworm infestation reduced plant performance, but increased the concentration of root defensive chemistry. Inoculation with insect-killing nematodes was ineffective, as they died rapidly in the warm and dry soil. An ant species however, invaded the experiment and were seen to be were more abundant in WCR-infested pots. The ants killed rootworm larvae regardless of soil moisture levels and root and shoot biomass increased in the presence of ants. Furthermore, the ants weakened the moisture-dependent effects of rootworm on maize cob weight, but not defensive plant chemistry. Our study identified a new natural enemy of rootworm larvae and showed that the tolerance of natural enemies to a changing environment can reduce the environment-dependent (soil moisture) impact of herbivores on plant performance. Enhancing the abundance and efficacy of adapted natural enemies may therefore protect crops from the negative impact of herbivores as the environment changes.

Technical Abstract: Climate change will strongly affect biotic interactions and plant productivity in natural and agricultural systems. However, little is known about the impact of climate change on plant performance in the presence of belowground herbivores and herbivore natural enemies. We investigated the effects of soil moisture on the interaction between maize, the western corn rootworm (WCR, Diabrotica virgifera), and soil-borne natural enemies and biocontrol agents of WCR. In a manipulative field experiment, decreasing soil moisture as well as WCR infestation reduced plant performance, but increased the concentration of root benzoxazinoids. Inoculation with entomopathogenic nematodes (EPNs, Heterorhabditis bacteriophora) was ineffective, as the EPNs died rapidly in the warm and dry soil. Ants of the species Solenopsis molesta on the other hand invaded the experiment, were more abundant in WCR-infested pots and predated WCR independently of soil moisture levels. Root and shoot biomass increased in the presence of ants. Furthermore, the ants attenuated the moisture-dependent effects of WCR on maize cob weight, but not defensive plant chemistry. Our study identifies S. molesta as a new natural enemy of WCR and shows that climate tolerance determines whether natural enemies can reduce the climate-dependent impacts of herbivores on plant performance. Enhancing the abundance and efficacy of adapted natural enemies may therefore protect crops from the negative impact of herbivores under climate change.