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Weigand AM, Desquiotz N, Weigand H, Szucsich N. Application of propylene glycol in DNA-based studies of invertebrates. METABARCODING AND METAGENOMICS 2021. [DOI: 10.3897/mbmg.5.57278] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
High-throughput sequencing (HTS) studies on invertebrates commonly use ethanol as the main sample fixative (upon collection) and preservative (for storage and curation). However, alternative agents exists, which should not be automatically neglected when studies are newly designed. This review provides an overview of the application of propylene glycol (PG) in DNA-based studies of invertebrates, thus to stimulate an evidence-based discussion.
The use of PG in DNA-based studies of invertebrates is still limited (n = 79), but a steady increase has been visible since 2011. Most studies used PG as a fixative for passive trapping (73%) and performed Sanger sequencing (66%; e.g. DNA barcoding). More recently, HTS setups joined the field (11%). Terrestrial Coleoptera (30%) and Diptera (20%) were the most studied groups. Very often, information on the grade of PG used (75%) or storage conditions (duration, temperature) were lacking. This rendered direct comparisons of study results difficult, and highlight the need for further systematic studies on these subjects.
When compared to absolute ethanol, PG can be more widely and cheaply acquired (e.g. as an antifreeze, 13% of studies). It also enables longer trapping intervals, being especially relevant at remote or hard-to-reach places. Shipping of PG-conserved samples is regarded as risk-free and is authorised, pinpointing its potential for larger trapping programs or citizen science projects. Its property to retain flexibility of morphological characters as well as to lead to a reduced shrinkage effect was especially appraised by integrative study designs. Finally, the so far limited application of PG in the context of HTS showed promising results for short read amplicon sequencing and reduced representation methods. Knowledge of the influence of PG fixation and storage for long(er) read HTS setups is currently unavailable.
Given our review results and taking difficulties of direct methodological comparisons into account, future DNA-based studies of invertebrates should on a case-by-case basis critically scrutinise if the application of PG in their anticipated study design can be of benefit.
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Perry KD, Keller MA, Baxter SW. Genome-wide analysis of diamondback moth, Plutella xylostella L., from Brassica crops and wild host plants reveals no genetic structure in Australia. Sci Rep 2020; 10:12047. [PMID: 32694639 PMCID: PMC7374630 DOI: 10.1038/s41598-020-68140-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 06/17/2020] [Indexed: 12/30/2022] Open
Abstract
Molecular studies of population structure can reveal insight into the movement patterns of mobile insect pests in agricultural landscapes. The diamondback moth, Plutella xylostella L., a destructive pest of Brassica vegetable and oilseed crops worldwide, seasonally colonizes winter canola crops in southern Australia from alternative host plant sources. To investigate movement, we collected 59 P. xylostella populations from canola crops, Brassica vegetable and forage crops and brassicaceous wild host plants throughout southern Australia in 2014 and 2015 and genotyped 833 individuals using RAD-seq for genome-wide analysis. Despite a geographic sampling scale > 3,000 km and a statistically powerful set of 1,032 SNP markers, there was no genetic differentiation among P. xylostella populations irrespective of geographic location, host plant or sampling year, and no evidence for isolation-by-distance. Hierarchical STRUCTURE analysis at K = 2–5 showed nearly uniform ancestry in both years. Cluster analysis showed divergence of a small number of individuals at several locations, possibly reflecting an artefact of sampling related individuals. It is likely that genetic homogeneity within Australian P. xylostella largely reflects the recent colonization history of this species but is maintained through some level of present gene flow. Use of genome-wide neutral markers was uninformative for revealing the seasonal movements of P. xylostella within Australia, but may provide more insight in other global regions where the species has higher genetic diversity.
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Affiliation(s)
- Kym D Perry
- School of Agriculture Food and Wine, University of Adelaide, Adelaide, 5005, Australia. .,Entomology Unit, South Australian Research and Development Institute, Adelaide, 5001, Australia.
| | - Michael A Keller
- School of Agriculture Food and Wine, University of Adelaide, Adelaide, 5005, Australia
| | - Simon W Baxter
- School of BioSciences, University of Melbourne, Melbourne, 3010, Australia.
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Angelella GM, Michel AP, Kaplan I. Using host-associated differentiation to track source population and dispersal distance among insect vectors of plant pathogens. Evol Appl 2019; 12:692-704. [PMID: 30976303 PMCID: PMC6439873 DOI: 10.1111/eva.12733] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/22/2018] [Accepted: 10/26/2018] [Indexed: 02/05/2023] Open
Abstract
Small, mobile insects are notoriously challenging to track across landscapes and manage in agricultural fields. However, genetic differentiation among insect populations and host plants acquired through host-associated differentiation could be exploited to infer movement within crop systems and damage potential. Although many insects exhibit host-associated differentiation, management strategies for insect vectors of plant pathogens assume a homogenous population. Nevertheless, phenotypic changes derived from host-associated differentiation could manifest in altered behavior or physiology affecting the likelihood of vector-pathogen-plant interactions, or the subsequent efficiency of pathogen transmission. We used SNPs to assess genotypic structure and host-associated differentiation in the cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae). To do so, we sampled A. craccivora across the Midwestern United States. from two host plants, alfalfa (Medicago sativa) and black locust (Robinia pseudoacacia)-putative source populations for winged migrants. Simultaneously, we sampled winged A. craccivora landing in pumpkin fields where they transmit viruses. Structure analyses supported host-associated differentiation by identifying two major genotypic groups: an alfalfa group containing a single multilocus genotype and a locust group containing all others. Winged locust-group aphids landed at a much greater magnitude within focal fields during year 2 than year 1, while those in the alfalfa group remained fairly consistent. Spatial autocorrelation analyses indicated locust-group aphid movement was characterized by small-scale dispersal during year 2, likely originating from populations within 10 km. We also detected strong temporal differences in colonization from the two host plants. Early in the summer, most winged aphids (79.4%) derived from the locust group, whereas late in the summer more (58.3%) were from the alfalfa group. Because early crop growth stages are more susceptible to damage from aphid-vectored viruses, these data implicate locust as the more important source and illustrate how host-associated differentiation can be used to track dispersal and inform management of heterogeneous pest populations.
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Affiliation(s)
- Gina Marie Angelella
- Department of EntomologyPurdue UniversityLafayetteIndiana
- Present address:
Department of HorticultureVirginia Tech University, Eastern Shore Agricultural Research and Extension CenterPainterVirginia
| | - Andy P. Michel
- Department of EntomologyThe Ohio State UniversityWoosterOhio
| | - Ian Kaplan
- Department of EntomologyPurdue UniversityLafayetteIndiana
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Fu Z, Epstein B, Kelley JL, Zheng Q, Bergland AO, Castillo Carrillo CI, Jensen AS, Dahan J, Karasev AV, Snyder WE. Using NextRAD sequencing to infer movement of herbivores among host plants. PLoS One 2017; 12:e0177742. [PMID: 28505182 PMCID: PMC5432177 DOI: 10.1371/journal.pone.0177742] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 05/02/2017] [Indexed: 12/29/2022] Open
Abstract
Herbivores often move among spatially interspersed host plants, tracking high-quality resources through space and time. This dispersal is of particular interest for vectors of plant pathogens. Existing molecular tools to track such movement have yielded important insights, but often provide insufficient genetic resolution to infer spread at finer spatiotemporal scales. Here, we explore the use of Nextera-tagmented reductively-amplified DNA (NextRAD) sequencing to infer movement of a highly-mobile winged insect, the potato psyllid (Bactericera cockerelli), among host plants. The psyllid vectors the pathogen that causes zebra chip disease in potato (Solanum tuberosum), but understanding and managing the spread of this pathogen is limited by uncertainty about the insect's host plant(s) outside of the growing season. We identified 1,978 polymorphic loci among psyllids separated spatiotemporally on potato or in patches of bittersweet nightshade (S. dulcumara), a weedy plant proposed to be the source of potato-colonizing psyllids. A subset of the psyllids on potato exhibited genetic similarity to insects on nightshade, consistent with regular movement between these two host plants. However, a second subset of potato-collected psyllids was genetically distinct from those collected on bittersweet nightshade; this suggests that a currently unrecognized source, i.e., other nightshade patches or a third host-plant species, could be contributing to psyllid populations in potato. Oftentimes, dispersal of vectors of pathogens must be tracked at a fine scale in order to understand, predict, and manage disease spread. We demonstrate that emerging sequencing technologies that detect genome-wide SNPs of a vector can be used to infer such localized movement.
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Affiliation(s)
- Zhen Fu
- Department of Entomology, Washington State University, Pullman, Washington, United States of America
| | - Brendan Epstein
- School of Biological Sciences, Washington State University, Pullman, Washington, United States of America
| | - Joanna L. Kelley
- School of Biological Sciences, Washington State University, Pullman, Washington, United States of America
| | - Qi Zheng
- Department of Bioinformatics and Biostatistics, University of Louisville, Louisville, Kentucky, United States of America
| | - Alan O. Bergland
- Department of Biology, Stanford University, Stanford, California, United States of America
| | | | - Andrew S. Jensen
- Northwest Potato Research Consortium, Lakeview, Oregon, United States of America
| | - Jennifer Dahan
- Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Alexander V. Karasev
- Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - William E. Snyder
- Department of Entomology, Washington State University, Pullman, Washington, United States of America
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Davis TS, Wu Y, Eigenbrode SD. The Effects of Bean Leafroll Virus on Life History Traits and Host Selection Behavior of Specialized Pea Aphid (Acyrthosiphon pisum, Hemiptera: Aphididae) Genotypes. ENVIRONMENTAL ENTOMOLOGY 2017; 46:68-74. [PMID: 28062535 DOI: 10.1093/ee/nvw150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Indexed: 06/06/2023]
Abstract
Intraspecific specialization by insect herbivores on different host plant species contributes to the formation of genetically distinct "host races," but the effects of plant virus infection on interactions between specialized herbivores and their host plants have barely been investigated. Using three genetically and phenotypically divergent pea aphid clones (Acyrthosiphon pisum L.) adapted to either pea (Pisum sativum L.) or alfalfa (Medicago sativa L.), we tested how infection of these hosts by an insect-borne phytovirus (Bean leafroll virus; BLRV) affects aphid performance and preference. Four important findings emerged: 1) mean aphid survival rate and intrinsic rate of population growth (Rm) were increased by 15% and 14%, respectively, for aphids feeding on plants infected with BLRV; 2) 34% of variance in survival rate was attributable to clone × host plant interactions; 3) a three-way aphid clone × host plant species × virus treatment significantly affected intrinsic rates of population growth; and 4) each clone exhibited a preference for either pea or alfalfa when choosing between noninfected host plants, but for two of the three clones tested these preferences were modestly reduced when selecting among virus-infected host plants. Our studies show that colonizing BLRV-infected hosts increased A. pisum survival and rates of population growth, confirming that the virus benefits A. pisum. BLRV transmission affected aphid discrimination of host plant species in a genotype-specific fashion, and we detected three unique "virus-association phenotypes," with potential consequences for patterns of host plant use by aphid populations and crop virus epidemiology.
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Affiliation(s)
- T S Davis
- Forest & Rangeland Stewardship, Colorado State University, CO
| | - Y Wu
- Plant, Soil, and Entomological Sciences, University of Idaho, Moscow, ID (; )
| | - S D Eigenbrode
- Plant, Soil, and Entomological Sciences, University of Idaho, Moscow, ID (; )
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