Plant-associated CO2 mediates long-distance host location and foraging behaviour of a root herbivore.

Carla CM Arce,Vanitha Theepan,Geoffrey Jaffuel,Matthias Erb,Bernardus CJ Schimmel,Ricardo AR Machado

doi:10.7554/elife.65575

Carla CM Arce, Vanitha Theepan + Show 4 more

Open Access

https://doi.org/10.7554/elife.65575

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Journal: eLife	Publication Date: Apr 20, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: University of Neuchâtel, University of Bern

Abstract

Insect herbivores use different cues to locate host plants. The importance of CO2 in this context is not well understood. We manipulated CO2 perception in western corn rootworm (WCR) larvae through RNAi and studied how CO2 perception impacts their interaction with their host plant. The expression of a carbon dioxide receptor, DvvGr2, is specifically required for dose-dependent larval responses to CO2. Silencing CO2 perception or scrubbing plant-associated CO2 has no effect on the ability of WCR larvae to locate host plants at short distances (<9 cm), but impairs host location at greater distances. WCR larvae preferentially orient and prefer plants that grow in well-fertilized soils compared to plants that grow in nutrient-poor soils, a behaviour that has direct consequences for larval growth and depends on the ability of the larvae to perceive root-emitted CO2. This study unravels how CO2 can mediate plant-herbivore interactions by serving as a distance-dependent host location cue.

Highlights

Insect herbivores can use different cues to locate suitable host plants from a distance
The release of CO2 from maize roots can account for the CO2 difference between soil trays with and without plants. This experiment shows that elevated CO2 levels derived from roots and probably from root-associated microorganisms are temporally and spatially associated with the presence of maize roots, and may be used as a host location cue by the western corn rootworm (WCR)
We conducted gene sequence similarity analyses, phylogenetic relationship reconstructions, RNA interference, and behavioural experiments to explore the biological relevance of rootassociated CO2 for plant–herbivore interactions

Summary

Introduction

Insect herbivores can use different cues to locate suitable host plants from a distance. In particular, can convey information about the identity and physiological status of a host plant and are integrated by herbivores to locate host plants for oviposition and feeding (Visser and Ave, 1978). While the role of plant volatiles such as green-leaf volatiles, aromatic compounds, and terpenes is well understood, much less is known about the role of plant-associated carbon dioxide (CO2) in plant–herbivore interactions. As CO2 at corresponding concentrations is attractive to the flies, it has been suggested that they may use plant-associated CO2 to locate suitable oviposition sites (Stange, 1999)

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