Interaction between maize root-associated microorganisms and the Western Corn Rootworm

Abstract

The Western Corn Rootworm (WCR, Diabrotica virgifera virgifera LeConte) is an important maize pest in North America and Europe. This thesis aimed (i) to investigate the effect of the root larval feeding on the microbial community in the rhizosphere of four maize genotypes grown in three different soil types (chapter 3); (ii) to study the complex interactions among WCR, Glomus intraradices (G.i.) and microbial communities in the rhizosphere and endorhiza of maize plants (chapter 4); (iii) to investigate the effect of the soil type on the fungal and bacterial communities inhabiting the eggs and the digestive tract of WCR larvae (chapter 5). The research described in chapter 3 revealed that the root feeding of WCR larvae increased the abundance of the bacterial population Acinetobacter calcoaceticus.In chapter 4 has been shown that G.i. reduces the WCR larval development. Shifts of the bacterial and fungal community composition in the rhizosphere and in root of G.i.-treated plants were observed, suggesting that G.i could contribute to the control of WCR larvae either directly or indirectly through shifts in the endophytic microbial communities via plant-mediated mechanisms.In chapter 5 we demonstrated that the soil type does not influence bacterial and fungal communities in the gut of WCR larvae. Relatively simple microbial communities dominated the WCR gut: Fusarium spp. and Gibberella zeae were dominant within the fungi, while Wolbachia sp. and Herbaspirillum sp. were dominant within the bacteria. In conclusion, the results acquired in this thesis provided additional insight into the multitrophic interaction among WCR larvae and rhizospheric- and root-associated microorganisms of maize plants.