Robert G. Foottit

Species identification of aphids (Insecta: Hemiptera: Aphididae) through DNA barcodes.

A 658‐bp fragment of mitochondrial DNA from the 5′ region of the mitochondrial cytochrome c oxidase 1 (COI) gene has been adopted as the standard DNA barcode region for animal life. In this study, we test its effectiveness in the discrimination of over 300 species of aphids from more than 130 genera. Most (96%) species were well differentiated, and sequence variation within species was low, averaging just 0.2%. Despite the complex life cycles and parthenogenetic reproduction of aphids, DNA barcodes are an effective tool for identification.

Insect Biodiversity: Science and Society

Preface. Acknowledgements. 1. Introduction Peter H. Adler and Robert G. Foottit . 2. The Importance of Insects G.G.E. Scudder . Part I. Insect Biodiversity: Regional Examples . 3. Insect Biodiversity in the Nearctic Region Andrew B. T. Smith and Hugh V. Danks. 4. Amazonian Rainforests and Their Richness of Coleoptera, a Dominant Life Form in the Critical Zone of the Neotropics Terry L. Erwin and Christy J. Geraci. 5. Insect Biodiversity in the Afrotropical Region C.H. Scholtz and M.W. Mansell . 6. Biodiversity of Australasian Insects Peter S. Cranston . 7. Insect Biodiversity in the Palearctic Region Alexander S. Konstantinov, Boris A. Korotyaev and Mark G. Volkovitsh. Part II. Insect Biodiversity: Taxon Examples. 8. Biodiversity of Aquatic Insects John C. Morse. 9. Biodiversity of Diptera G.W. Courtney, T. Pape, J.H. Skevington and B.J. Sinclair . 10. Biodiversity of Heteroptera Thomas J. Henry. 11. Biodiversity of Coleoptera P. Bouchard, V.V. Grebennikov, A.B.T. Smith and H. Douglas. 12. Biodiversity of Hymenoptera John T. Huber . 13. Lepidoptera Biodiversity Michael G. Pogue. Part III. Tools and Approaches . 14. The Science of Insect Taxonomy: Prospects and Needs Quentin D. Wheeler . 15. Insect Species - Concepts and Practice Michael F. Claridge . 16. Molecular Dimensions of Insect Taxonomy Felix Sperling and Amanda Roe . 17. DNA Barcodes and Insect Biodiversity Robin M. Floyd, John J. Wilson, Paul D. N. Hebert . 18. Insect Biodiversity and Informatics Norman F. Johnson . 19. Parasitoid Diversity and Insect Pest Management John Heraty . 20. Taxonomy of Crop Pests: The Aphids Gary L. Miller and Robert G. Foottit . 21. Adventive Insects: A Global Overview Alfred G. Wheeler, Jr. and E. Richard Hoebeke . 22. Biodiversity of Biting Flies: Implications for Humanity Peter H. Adler . 23. Reconciling Ethical and Scientific Issues for Insect Conservation Michael J. Samways . 24. Insect Biodiversity: Assessment and Taxonomy Ke Chung Kim. 25. Insect Biodiversity - Millions and Millions May Berenbaum. Taxonomic Index. Subject Index

Barcoding Bugs: DNA-Based Identification of the True Bugs (Insecta: Hemiptera: Heteroptera)

Background DNA barcoding, the analysis of sequence variation in the 5′ region of the mitochondrial cytochrome c oxidase I (COI) gene, has been shown to provide an efficient method for the identification of species in a wide range of animal taxa. In order to assess the effectiveness of barcodes in the discrimination of Heteroptera, we examined 344 species belonging to 178 genera, drawn from specimens in the Canadian National Collection of Insects. Methodology/Principal Findings Analysis of the COI gene revealed less than 2% intra-specific divergence in 90% of the taxa examined, while minimum interspecific distances exceeded 3% in 77% of congeneric species pairs. Instances where barcodes fail to distinguish species represented clusters of morphologically similar species, except one case of barcode identity between species in different genera. Several instances of deep intraspecific divergence were detected suggesting possible cryptic species. Conclusions/Significance Although this analysis encompasses 0.8% of the described global fauna, our results indicate that DNA barcodes will aid the identification of Heteroptera. This advance will be useful in pest management, regulatory and environmental applications and will also reveal species that require further taxonomic research.

Barcoding aphids (Hemiptera: Aphididae) of the Korean Peninsula: updating the global data set

DNA barcode (mitochondrial COI) sequences are provided for species identification of aphids from the Korean Peninsula. Most (98%) of the 154 species had distinct COI sequences (average 0.05% intraspecific pairwise divergence) relative to the degree of sequence divergence among species (average value 5.84%). For species in common with other regions, barcodes for Korean samples fell near or within known levels of variation. Based on these results, we conclude that DNA barcodes can provide an effective tool for identifying aphid species in such applications as pest management, monitoring and plant quarantine.

Diversity of non-native terrestrial arthropods on woody plants in Canada

A list of non-native phytophagous insects and mites on woody plants (trees, shrubs, vines) in Canada was compiled using information from literature and input from taxonomists. The 419 recorded species include Hemiptera (53% of species), Lepidoptera (22%), Coleoptera (13%) and Hymenoptera (9%). Almost all species originate from the Palearctic, especially Europe, reflecting historical trade patterns. About 41% of species were directly introduced to Canada from countries of origin, and the remainder spread from the United States of America (USA) after initial establishment there. Major ports on the east and west coasts, on Lake Erie and Lake Ontario are the main points of entry for exotic species directly introduced, and southern British Columbia (BC), Ontario (ON) and Quebec (QC) are the major points of entry for species spreading from the USA. Consequently, BC, ON, QC and Nova Scotia have the highest diversity of non-native species, and the prairie provinces and northern territories have the lowest. The extent of the distribution of individual species is related to length of time in Canada, number of introductions and dispersal abilities. Almost all native woody plant genera in Canada have been invaded by exotic phytophages. The large majority of phytophages occur on angiosperms. Woody plant genera with the largest distribution, highest species diversity and highest local abundances tend to host the greatest number of non-native species, including Picea, Pinus, Malus, Prunus, Salix, Betula, Quercus, Pyrus and Populus. The arrival rate of species in Canada increased from the late nineteenth century until about 1960, and declined rapidly thereafter. Quarantine legislation enacted in the USA in 1912 and in Canada in 1976 seems to have reduced the rate of insect invasion.

Reconstructing the phylogeny of aphids (Hemiptera: Aphididae) using DNA of the obligate symbiont Buchnera aphidicola

Reliable phylogenetic reconstruction, as a framework for evolutionary inference, may be difficult to achieve in some groups of organisms. Particularly for lineages that experienced rapid diversification, lack of sufficient information may lead to inconsistent and unstable results and a low degree of resolution. Coincidentally, such rapidly diversifying taxa are often among the biologically most interesting groups. Aphids provide such an example. Due to rapid adaptive diversification, they feature variability in many interesting biological traits, but consequently they are also a challenging group in which to resolve phylogeny. Particularly within the family Aphididae, many interesting evolutionary questions remain unanswered due to phylogenetic uncertainties. In this study, we show that molecular data derived from the symbiotic bacteria of the genus Buchnera can provide a more powerful tool than the aphid-derived sequences. We analyze 255 Buchnera gene sequences from 70 host aphid species and compare the resulting trees to the phylogenies previously retrieved from aphid sequences, only. We find that the host and symbiont data do not conflict for any major phylogenetic conclusions. Also, we demonstrate that the symbiont-derived phylogenies support some previously questionable relationships and provide new insights into aphid phylogeny and evolution.

DNA barcodes to identify species and explore diversity in the Adelgidae (Insecta: Hemiptera: Aphidoidea)

The Adelgidae are relatively small, cryptic insects, exhibiting complex life cycles with parthenogenetic reproduction. Due to these characteristics, the taxonomy of the group is problematic. Here, we test the effectiveness of the standard 658‐bp barcode fragment from the 5′‐end of the mitochondrial cytochrome c oxidase 1 gene (COI) in differentiating among 17 species of Adelgidae, in associating life‐cycle stages, and in assessing patterns of geographical variation in selected species. Species of Adelgidae are well‐differentiated by DNA barcodes, enabling the identification of different morphological forms, immature stages and individuals on different hosts and at different periods of the life cycle. DNA barcodes have uncovered cryptic diversity within taxa and, in other cases, a lack of sequence divergence in species pairs previously separated by life‐cycle characteristics, indicating a need for further taxonomic analysis.

Is ecological speciation a major trend in aphids? Insights from a molecular phylogeny of the conifer-feeding genus Cinara

IntroductionIn the past decade ecological speciation has been recognized as having an important role in the diversification of plant-feeding insects. Aphids are host-specialised phytophagous insects that mate on their host plants and, as such, they are prone to experience reproductive isolation linked with host plant association that could ultimately lead to species formation. The generality of such a scenario remains to be tested through macroevolutionary studies. To explore the prevalence of host-driven speciation in the diversification of the aphid genus Cinara and to investigate alternative modes of speciation, we reconstructed a phylogeny of this genus based on mitochondrial, nuclear and Buchnera aphidicola DNA sequence fragments and applied a DNA-based method of species delimitation. Using a recent software (PhyloType), we explored evolutionary transitions in host-plant genera, feeding sites and geographic distributions in the diversification of Cinara and investigated how transitions in these characters have accompanied speciation events.ResultsThe diversification of Cinara has been constrained by host fidelity to conifer genera sometimes followed by sequential colonization onto different host species and by feeding-site specialisation. Nevertheless, our analyses suggest that, at the most, only half of the speciation events were accompanied by ecological niche shifts. The contribution of geographical isolation in the speciation process is clearly apparent in the occurrence of species from two continents in the same clades in relatively terminal positions in our phylogeny. Furthermore, in agreement with predictions from scenarios in which geographic isolation accounts for speciation events, geographic overlap between species increased significantly with time elapsed since their separation.ConclusionsThe history of Cinara offers a different perspective on the mode of speciation of aphids than that provided by classic models such as the pea aphid. In this genus of aphids, the role of climate and landscape history has probably been as important as host-plant specialisation in having shaped present-day diversity.

The hemiptera (insecta) of Canada: constructing a reference library of DNA barcodes.

DNA barcode reference libraries linked to voucher specimens create new opportunities for high-throughput identification and taxonomic re-evaluations. This study provides a DNA barcode library for about 45% of the recognized species of Canadian Hemiptera, and the publically available R workflow used for its generation. The current library is based on the analysis of 20,851 specimens including 1849 species belonging to 628 genera and 64 families. These individuals were assigned to 1867 Barcode Index Numbers (BINs), sequence clusters that often coincide with species recognized through prior taxonomy. Museum collections were a key source for identified specimens, but we also employed high-throughput collection methods that generated large numbers of unidentified specimens. Many of these specimens represented novel BINs that were subsequently identified by taxonomists, adding barcode coverage for additional species. Our analyses based on both approaches includes 94 species not listed in the most recent Canadian checklist, representing a potential 3% increase in the fauna. We discuss the development of our workflow in the context of prior DNA barcode library construction projects, emphasizing the importance of delineating a set of reference specimens to aid investigations in cases of nomenclatural and DNA barcode discordance. The identification for each specimen in the reference set can be annotated on the Barcode of Life Data System (BOLD), allowing experts to highlight questionable identifications; annotations can be added by any registered user of BOLD, and instructions for this are provided.

A New Approach for the Identification of Aphid Vectors (Hemiptera: Aphididae) of Potato Virus Y

ABSTRACT Potato virus Y (PVY) is one of the most economically important viruses affecting potato crops worldwide. PVY can be transmitted from potato to potato by several aphid species, most of which do not colonize the potato crop. New methods including preservation of viral RNA on stylets of aphids collected from yellow pan trap samples, polymerase chain reaction detection of PVY from the stylets of one aphid, and aphid identification using DNA barcoding were used to identify possible PVY vectors from field samples. In total, 65 aphid taxa were identified from the samples that tested positive for PVY. Among those, 45 taxa had never been evaluated for their ability to transmit PVY, and 7 were previously labeled as nonvectors. These results demonstrated that the list of PVY vectors is likely longer than previously reported and that most (if not all) species of aphids could be considered as potential vectors. This premise has important implications in the management of PVY in seed potato production.