Multitrophic interactions among Western Corn Rootworm, Glomus intraradices and microbial communities in the rhizosphere and endorhiza of maize.

Flavia Dematheis,Stefan Vidal,Kornelia Smalla,Benedikt Kurtz

doi:10.3389/fmicb.2013.00357

Flavia Dematheis, Stefan Vidal + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2013.00357

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Abstract

The complex interactions among the maize pest Western Corn Rootworm (WCR), Glomus intraradices (GI—recently renamed Rhizophagus intraradices) and the microbial communities in both rhizosphere and endorhiza of maize have been investigated in view of new pest control strategies. In a greenhouse experiment, different maize treatments were established: C (control plants), W (plants inoculated with WCR), G (plants inoculated with GI), GW (plants inoculated with GI and WCR). After 20 days of WCR root feeding, larval fitness was measured. Dominant arbuscular mycorrhizal fungi (AMF) in soil and maize endorhiza were analyzed by cloning of 18S rRNA gene fragments of AMF, restriction fragment length polymorphism and sequencing. Bacterial and fungal communities in the rhizosphere and endorhiza were investigated by denaturing gradient gel electrophoresis of 16S rRNA gene and ITS fragments, PCR amplified from total community DNA, respectively. GI reduced significantly WCR larval development and affected the naturally occurring endorhiza AMF and bacteria. WCR root feeding influenced the endorhiza bacteria as well. GI can be used in integrated pest management programs, rendering WCR larvae more susceptible to predation by natural enemies. The mechanisms behind the interaction between GI and WCR remain unknown. However, our data suggested that GI might act indirectly via plant-mediated mechanisms influencing the endorhiza microbial communities.

Highlights

The Western Corn Rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an invasive maize pest in North America and in Europe (Wesseler and Fall, 2010)
We addressed the following questions: (1) Does Glomus intraradices (GI) mycorrhization of maize roots affect the WCR larval fitness measured as larval number/survival, developmental stage and root feeding? (2) Does GI mycorrhization affect the composition of microbial populations in the rhizosphere and endorhiza of maize? (3) Does the feeding of WCR larvae alter the microbial communities in the endorhiza and rhizosphere of mycorrhized and unmycorrhized maize plants?
The remaining plants were used to assess the following treatments: C, W, G and GW

Summary

Introduction

The Western Corn Rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an invasive maize pest in North America and in Europe (Wesseler and Fall, 2010). The concentration of cry(3Bb1) expressed in Bt maize is not considered a high dose for WCR (Al-Deeb and Wilde, 2005; Oyediran et al, 2007), and resistance was reported to build up within three generations of selection on Bt maize in greenhouse experiments (Meihls et al, 2008; Gassmann et al, 2011). Another strategy, widely used in the past in the United States (U.S.) for managing the WCRs is the crop rotation. An improved knowledge of the ecology of this soil-dwelling insect and its multitrophic interactions in the rhizosphere and endorhiza are important prerequisites to achieve this goal

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