Detection of Wolbachia Infections in Natural and Laboratory Populations of the Moroccan Hessian Fly, Mayetiola destructor (Say)

Abstract

Mayetiola destructor (Hessian fly) is a destructive pest of wheat in several parts of the world. Here, we investigated the presence of reproductive symbionts and the effect of the geographical location on the bacterial community associated to adult Hessian flies derived from four major wheat producing areas in Morocco. Using specific 16S rDNA PCR assay, Wolbachia infection was observed in 3% of the natural populations and 10% of the laboratory population. High throughput sequencing of V3-V4 region of the bacterial 16S rRNA gene revealed that the microbiota of adult Hessian flies was significantly influenced by their native regions. A total of 6 phyla, 10 classes and 79 genera were obtained from all the samples. Confirming the screening results, Wolbachia was identified as well in the natural Hessian flies. Phylogenetic analysis using the sequences obtained in this study indicated that there is one Wolbachia strain belonging to supergroup A. To our knowledge, this is the first report of Wolbachia in Hessian fly populations. The observed low abundance of Wolbachia most likely does not indicate induction of reproductive incompatibility. Yet, this infection may give a new insight into the use of Wolbachia for the fight against Hessian fly populations.

Keywords: 16S rRNA gene; HTS; Hessian fly; biological control; high throughput sequencing.

Figure 1

Maximum likelihood phylogenetic tree based on Wolbachia 16S rRNA sequences (257 bp indel-free alignment): The thirteen Wolbachia sequences present in Hessian fly positive samples are indicated in bold letters (D: samples from Doukkala region, Lab: samples from the laboratory colony) along with the other sequences represent the known supergroups from A to Q (except supergroup P). Wolbachia sequences are characterized by the names of their host species and their GenBank accession number. The number in each node represent bootstrap proportions based on 1000 replication (only values > 50% are indicated).

Figure 2

Species richness and diversity indices with significance differences of Hessian fly samples collected from Chaouia, Doukkala, Fes and Safi regions. Boxes represent inter-quartile range (IQR), the line within the boxes is the median, and the dots represent samples. * p < 0.05, ** p < 0.01 and *** p < 0.001.

Figure 3

Composition of Hessian flies’ microbiota at the phylum (a) and genus (b) levels. ‘p’ corresponds to phylum, ‘c’ to class and ‘g’ to genus.

Figure 4

Maximum likelihood phylogenetic tree based on 16S rRNA gene of Wolbachia related OTU (443 bp full size alignment): The Wolbachia related sequence obtained from Hessian fly positive samples is indicated in bold letters along with the other sequences represent the known supergroups from A to Q. Wolbachia sequences are characterized by the names of their host species and their GenBank accession number. The number in each node represent bootstrap proportions based on 1000 replication (only values > 50% are indicated).

Figure 5

Non-metric multidimensional scaling (NMDS) plot of bacterial communities for Hessian flies samples collected from Chaouia (red), Doukkala (green), Fes (cyan) and Safi (purple) (p < 0.001). ‘d’ indicates dissimilarity scale of the grid (d = 0.1 mean that the distance between two grid lines represent approximately 10% dissimilarity between the samples).