Immigrant Tortricidae: Holarctic Versus Introduced Species in North America
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insects Article Immigrant Tortricidae: Holarctic versus Introduced Species in North America Todd M. Gilligan 1,*, John W. Brown 2 and Joaquín Baixeras 3 1 USDA-APHIS-PPQ-S&T, 2301 Research Boulevard, Suite 108, Fort Collins, CO 80526, USA 2 Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA; [email protected] 3 Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Carrer Catedràtic José Beltran, 2, 46980 Paterna, Spain; [email protected] * Correspondence: [email protected] Received: 13 August 2020; Accepted: 29 August 2020; Published: 3 September 2020 Simple Summary: The family Tortricidae includes approximately 11,500 species of small moths, many of which are economically important pests worldwide. A large number of tortricid species have been inadvertently introduced into North America from Eurasia, and many have the potential to inflict considerable negative economic and ecological impacts. Because native species behave differently than introduced species, it is critical to distinguish between the two. Unfortunately, this can be a difficult task. In the past, many tortricids discovered in North America were assumed to be the same as their Eurasian counterparts, i.e., Holarctic. Using DNA sequence data, morphological characters, food plants, and historical records, we analyzed the origin of 151 species of Tortricidae present in North America. The results indicate that the number of Holarctic species has been overestimated by at least 20%. We also determined that the number of introduced tortricids in North America is unexpectedly high compared other families, with tortricids accounting for approximately 23–30% of the total number of moth and butterfly species introduced to North America. This suggests that introduced tortricids have a greater potential of becoming economically important pests than moths in other families, and why distinguishing Holarctic from introduced species is critical to American agriculture. Abstract: In support of a comprehensive update to the checklist of the moths of North America, we attempt to determine the status of 151 species of Tortricidae present in North America that may be Holarctic, introduced, or sibling species of their European counterparts. Discovering the natural distributions of these taxa is often difficult, if not impossible, but several criteria can be applied to determine if a species that is present in both Europe and North America is natively Holarctic, introduced, or represented by different but closely related species on each continent. We use DNA barcodes (when available), morphology, host plants, and historical records (literature and museum specimens) to make these assessments and propose several taxonomic changes, as well as future areas of research. The following taxa are raised from synonymy to species status: Acleris ferrumixtana (Benander, 1934), stat. rev.; Acleris viburnana (Clemens, 1860), stat. rev.; Acleris pulverosana (Walker, 1863), stat. rev.; Acleris placidana (Robinson, 1869), stat. rev.; Lobesia spiraeae (McDunnough, 1938), stat. rev.; and Epiblema arctica Miller, 1985, stat. rev. Cydia saltitans (Westwood, 1858), stat. rev., is determined to be the valid name for the “jumping bean moth,” and Phiaris glaciana (Möschler, 1860), comb. n., is placed in a new genus. We determine that the number of Holarctic species has been overestimated by at least 20% in the past, and that the overall number of introduced species in North America is unexpectedly high, with Tortricidae accounting for approximately 23–30% of the total number of Lepidoptera species introduced to North America. Keywords: Olethreutinae; Tortricinae; DNA barcoding; Beringian; taxonomy Insects 2020, 11, 594; doi:10.3390/insects11090594 www.mdpi.com/journal/insects Insects 2020, 11, 594 2 of 59 1. Introduction Globalization, the international movement of commodities and people among different nations, has dramatically increased the spread of plant and animal species around the world, e.g., [1–3]. Among these “introduced” or “exotic” species, insects are the most pervasive, representing 87% of the approximately 2500 nonnative terrestrial invertebrates in Europe [4]. According to Lovett et al. [5], nonnative insect species have accumulated in United States forests at a rate of approximately 2.5 per year over the last 150 years, with the gypsy moth (Lymantria dispar (Linnaeus, 1758), Erebidae) being among the most notorious. Examples of important lepidopteran pests that have been introduced recently to new regions around the globe include the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Noctuidae), a native of the New World that has spread to much of Africa and Asia [6,7] and was recently discovered in Australia [8]; the Old World bollworm, Helicoverpa armigera (Hübner) (Noctuidae), which was first reported in the New World in Brazil and has spread to much of South America and the Caribbean [9–11]; the light brown apple moth, Epiphyas postvittana (Walker) (Tortricidae), a native of Australia that was documented from California in 2006 and has now spread throughout much of the state [12]; and the European grapevine moth, Lobesia botrana (Denis and Schiffermüller) ([Tortricidae]), a native of Europe that was inadvertently introduced to the wine-growing regions of Argentina, Chile, and California [13]. While these contemporary or recent arrivals to new regions are well documented, for many other species, there is considerable ambiguity regarding their origin and/or native distributions. For example, in North America, the discovery of a “European” species could indicate that the taxon was recently introduced, that it is natively Holarctic in distribution and previously undiscovered, or that it represents an unrecognized sibling species of its European counterpart. In the absence of direct evidence of an introduction, the taxonomist is left to speculate among these alternative explanations. In many cases, a compelling explanation is further complicated by the fact that many apparently European species are discovered along the northwestern or northeastern coasts of North America, regions where one would expect to find Holarctic elements or introductions owing to the proximity to major U.S. and Canadian ports of entry. In support of a comprehensive update to the checklist of the moths of North America [14], we determine the status of 151 species of Tortricidae present in North America that have been previously assumed to be Holarctic, or introduced, or whose status in the Nearctic was questionable. We use DNA barcodes (when available), morphology, host plants, and historical records (literature and museum specimens) to make these assessments, and we propose appropriate taxonomic changes where necessary. 2. Materials and Methods 2.1. Biogeographic Framework The Holarctic. The Holarctic is defined as the biogeographical region comprised of the Nearctic (North America) and the Palearctic (Eurasia and northern Africa). These continents have been variably linked since the breakup of Pangea approximately 180 mya. The following geographic history of the region is summarized from Hopkins [15], Enghoff [16], and Sanmartín et al. [17]. Following the breakup of Pangea, North America and Eurasia comprised the northern supercontinent Laurasia, which was split into two smaller paleocontinents, Euramerica (Europe and eastern North America) and Asiamerica (Asia and western North America) around 100–80 mya. The western Palearctic was separated from the eastern Palearctic by the Turgai Sea until ca. 30 mya, and the western Nearctic was separated from the eastern Nearctic until ca. 60 mya by the Mid-Continental Seaway. Europe and eastern North America were linked by several North Atlantic land bridges until sometime in the late Eocene (ca. 39 mya). Asia and western North America were connected by the Bering land bridge from the mid-Cretaceous (100 mya) continuously until the Late Pliocene (3.5 mya), but this connection was established again intermittently throughout the Pleistocene (1.5–0.011 mya) before it was submerged completely ca. 11,000 years ago. Insects 2020, 11, 594 3 of 59 These Trans-Beringian land bridges are assumed to have played an important role in dispersal across the Holarctic. Beringia underwent three distinct phases with associated changes in climate and vegetation [17]. Beringian Bridge I: A continuous belt of boreotropical forest extended over the entire Northern Hemisphere by the Early Eocene (ca. 50 mya), and the climate was much warmer and more humid than today. Beringian Bridge II: As the climate cooled and became drier, the forests transitioned to mixed deciduous hardwoods and conifers, and eventually only to conifer forests that were split into eastern and western portions. The marine transgression of the Bering Strait in the Late Pliocene (3.5 mya) permanently separated the Palearctic and Nearctic forests. Beringian Bridge III: As glaciation commenced in the Pleistocene (1.5–1.0 mya), the Beringian land bridge was once again established. Originally assumed to be a continuous “mammoth steppe” or “steppe tundra,” Elias et al. [18] found that the vegetation was dominated by birch-heath-graminoid tundra with little or no evidence of steppe elements. This land connection persisted intermittently during glaciation events until it was permanently interrupted at the end of the Pleistocene. It is generally assumed that trans-Beringian dispersal between the eastern Palearctic and western Nearctic