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Title: Effects of temperature and drought on plant-herbivore interactions in soybean (Glycine max)

item JOHNSON, MARC - North Carolina State University
item Carter Jr, Thomas
item GRINNAN, ROSE - North Carolina State University

Submitted to: Arthropod-Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2012
Publication Date: 4/1/2013
Citation: Johnson, M., Carter Jr, T.E., Grinnan, R. 2013. Effects of temperature and drought on plant-herbivore interactions in soybean (Glycine max). Arthropod-Plant Interactions. 7:201-215.

Interpretive Summary: Earth’s climate is rapidly changing and most climate models predict continued increases in temperature and greater variability in precipitation. The effects of these changes on agriculture are less certain, although it is widely believed that ongoing environmental change could profoundly affect food production. An important question for which we do not know the answer is: how will increased drought and heat affect insect problems in soybean production? Some speculate that they may foster increases in the frequency and severity of insect population outbreaks. We sought to answer this question by taking a simultaneous look at drought, heat, and insect damage on soybean. This is a novel approach. Fortunately, there was no clear interaction among these three factors, overall. However, the choice of soybean variety appears to have a big impact on this question (i.e. whether or not drought and heat can exacerbate insect problems). Combining both drought and insect resistance into a single soybean variety could go a long way toward mitigating negative climate change effects on soybean production.

Technical Abstract: Climate change is predicted to cause continued increases in global temperatures, greater variability in precipitation and in some cases, more frequent insect pest outbreaks. Here we seek to understand how climate change might affect plant-herbivore interactions in soybean, by answering three questions: 1) do the combined effects of abiotic and biotic stresses associated with climate change cause synergistic negative effects on plant performance; 2) can abiotic stress affect the susceptibility of plants to insect herbivores; and 3) does genetic variation in plant traits modify a plant’s response to stress? We performed three experiments in controlled growth environments using up to 51 soybean genotypes and 3 generalist-feeding herbivorous moth species (Helicoverpa zea, Heliothis virescens, Spodoptera exigua). Drought and herbivory had the largest and most consistent negative effects on plant performance, reducing above- and below-ground biomass by 10-45%, whereas increased temperature had little to no effect on plants. Drought also increased susceptibility to generalist herbivores, but these results varied dramatically in magnitude and direction among plant genotypes. Our results show that the effects of abiotic and biotic stress on soybean performance are largely due to the additive effects of these stresses, and there exists substantial genetic variation within soybean that could be used as a source of germplasm to mitigate future stresses associated with climate change.