Abstract
Climate change is predicted to increase the risk of drought in many temperate agroecosystems. While the impact of drought on aboveground plant‐herbivore‐natural enemy interactions has been studied, little is known about its effects on belowground tritrophic interactions and root defense chemistry. We investigated the effects of low soil moisture on the interaction between maize, the western corn rootworm (WCR, Diabrotica virgifera), and soil‐borne natural enemies of WCR. In a manipulative field experiment, reduced soil moisture and WCR attack reduced plant performance and increased benzoxazinoid levels. The negative effects of WCR on cob dry weight and silk emergence were strongest at low moisture levels. Inoculation with entomopathogenic nematodes (EPNs, Heterorhabditis bacteriophora) was ineffective in controlling WCR, and the EPNs died rapidly in the warm and dry soil. However, ants of the species Solenopsis molesta invaded the experiment, were more abundant in WCR‐infested pots and predated WCR independently of soil moisture. Ant presence increased root and shoot biomass and was associated with attenuated moisture‐dependent effects of WCR on maize cob weight. Our study suggests that apart from directly reducing plant performance, drought can also increase the negative effects of root herbivores such as WCR. It furthermore identifies S. molesta as a natural enemy of WCR that can protect maize plants from the negative impact of herbivory under drought stress. Robust herbivore natural enemies may play an important role in buffering the impact of climate change on plant‐herbivore interactions.
Highlights
Root herbivores are among the most damaging pests in agriculture (Hunter, 2001)
This study found that soil moisture altered the impact of a root herbivore on maize performance, and that these changes were absent in pots that were colonized by a naturally occurring herbivore enemy
anthesis-silking interval (ASI) and cob weight are strong indicators of plant yield and are used as a trait to select for drought-resistant maize cultivars (Cattivelli et al, 2008)
Summary
Root herbivores are among the most damaging pests in agriculture (Hunter, 2001). Their impact on plant performance depends on a number of factors, including host plant resistance (Huber et al., 2016), top-down control by natural enemies (Degenhardt et al, 2009), and abiotic environmental conditions (Erb & Lu, 2013). Despite the fact that soil moisture effects on plants, root herbivores, and natural enemies have been described, little is known about how drought will modulate belowground tritrophic interactions and thereby influence plant performance. To address this question, we investigated the influence of soil moisture on the interaction between maize, the western corn rootworm (WCR, Diabrotica virgifera virgifera; Figure 1), and its natural enemies in a semifield experiment. We hypothesized that drought reduces the capacity of natural enemies to control WCR and to alleviate its negative effects on plant performance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
