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Abstract The invasive brown widow spider,Latrodectus geometricus(Araneae: Theridiidae), has spread in multiple locations around the world and, along with it, brought associated organisms such as endosymbionts. We investigated endosymbiont diversity and prevalence across putative native and invasive populations of this spider, predicting lower endosymbiont diversity across the invasive range compared to the native range. First, we characterized the microbial community in the putative native (South Africa) and invasive (Israel and the United States) ranges via high throughput 16S sequencing of 103 adult females. All specimens were dominated by reads from only 1–3 amplicon sequence variants (ASV), and most individuals were infected with an apparently uniform strain ofRhabdochlamydia. We also foundRhabdochlamydiain spider eggs, indicating that it is a maternally-inherited endosymbiont. Relatively few other ASV were detected, but included two variantRhabdochlamydiastrains and severalWolbachia,Spiroplasmaand Enterobacteriaceae strains. We then diagnostically screened 118 adult female spiders from native and invasive populations specifically forRhabdochlamydiaandWolbachia.We foundRhabdochlamydiain 86% of individuals and represented in all populations, which suggests that it is a consistent and potentially important associate ofL. geometricus. Wolbachiawas found at lower overall prevalence (14%) and was represented in all countries, but not all populations. In addition, we found evidence for geographic variation in endosymbiont prevalence: spiders from Israel were more likely to carryRhabdochlamydiathan those from the US and South Africa, andWolbachiawas geographically clustered in both Israel and South Africa. Characterizing endosymbiont prevalence and diversity is a first step in understanding their function inside the host and may shed light on the process of spread and population variability in cosmopolitan invasive species.
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The Foliar Microbiome Suggests that Fungal and Bacterial Agents May be Involved in the Beech Leaf Disease Pathosystem
Beech leaf disease (BLD) is a recently discovered disease that is causing severe damage to American beech (Fagus grandifolia) in northeastern North America. The recently described nematode Litylenchus crenatae subsp. mccannii was detected in BLD-affected foliage and may be associated with the disease. However, speculation on the direct role of the nematode in infection still remains. In this study, we profiled the microbial communities associated with asymptomatic, symptomatic, and naïve (control) American beech foliage by using a high-throughput sequence-based metabarcoding analysis of fungi, bacteria, phytoplasmas, and nematodes. We then used both a differential abundance analysis and indicator species analysis as well as several diversity metrics to try and discover microbes associated only with symptomatic foliage. To do so, we amplified the organism-specific phylogenetic informative regions of the 16S, 18S, and internal transcribed spacer (ITS)1 regions using Illumina MiSeq. Our results detected the amplicon sequence variant (ASV) associated with the nematode L. crenatae subsp. mccannii but in all symptom types. However, four ASVs associated with the bacterial genera Wolbachia, Erwinia, Paenibacillus, and Pseudomonas and one ASV associated with the fungal genus Paraphaeosphaeria were detected only in symptomatic samples. In addition, we identified significant differences based on symptom type in both the α- and β-diversity indices for the bacterial and fungal communities. These results suggest that L. crenatae subsp. mccannii may not be fully responsible for BLD but, rather, that other microbes may be contributing to the syndrome, including the putative nematode endosymbiont Wolbachia sp.
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- Award ID(s):
- 1638999
- PAR ID:
- 10373355
- Date Published:
- Journal Name:
- Phytobiomes Journal
- Volume:
- 5
- Issue:
- 3
- ISSN:
- 2471-2906
- Page Range / eLocation ID:
- 335 to 349
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1094/PBIOMES-12-20-0088-R
