A literature survey identified 403 primary research publications that investigated the ecological effects of invasive alien insects and/or the mechanisms underlying these effects. The majority of these studies were published in the last 8 years and nearly two-thirds were carried out in North America. These publications concerned 72 invasive insect species, of which two ant species, Solenopsis invicta and Linepithema humile, accounted for 18% and 14% of the studies, respectively. Most publications investigated effects on native biodiversity at population or community level. Genetic effects and, to a lesser extent, effects on ecosystem services and processes were rarely explored. We review the effects caused by different insect invaders according to: their ecosystem roles, i.e. herbivores, predators, parasites, parasitoids and pollinators; the level of biological organisation at which they occur; and the direct and indirect mechanisms underlying these effects. The best documented effects occur in invasive ants, Eurasian forest herbivores invasive in North America, and honeybees. Impacts may occur through simple trophic interactions such as herbivory, predation or parasitism. Alien species may also affect native species and communities through more complex mechanisms such as competition for resources, disease transmission, apparent competition, or pollination disruption, among others. Finally, some invasive insects, particularly forest herbivores and ants, are known to affect ecosystem processes through cascading effects. We identify biases and gaps in our knowledge of ecological effects of invasive insects and suggest further opportunities for research.

The proliferation of DNA data is revolutionizing all fields of systematic research. DNA barcode sequences, now available for millions of specimens and several hundred thousand species, are increasingly used in algorithmic species delimitations. This is complicated by occasional incongruences between species and gene genealogies, as indicated by situations where conspecific individuals do not form a monophyletic cluster in a gene tree. In two previous reviews, non-monophyly has been reported as being common in mitochondrial DNA gene trees. We developed a novel web service “Monophylizer” to detect non-monophyly in phylogenetic trees and used it to ascertain the incidence of species non-monophyly in COI (a.k.a. cox1) barcode sequence data from 4977 species and 41,583 specimens of European Lepidoptera, the largest data set of DNA barcodes analyzed from this regard. Particular attention was paid to accurate species identification to ensure data integrity. We investigated the effects of tree-building method, sampling effort, and other methodological issues, all of which can influence estimates of non-monophyly. We found a 12% incidence of non-monophyly, a value significantly lower than that observed in previous studies. Neighbor joining (NJ) and maximum likelihood (ML) methods yielded almost equal numbers of non-monophyletic species, but 24.1% of these cases of non-monophyly were only found by one of these methods. Non-monophyletic species tend to show either low genetic distances to their nearest neighbors or exceptionally high levels of intraspecific variability. Cases of polyphyly in COI trees arising as a result of deep intraspecific divergence are negligible, as the detected cases reflected misidentifications or methodological errors. Taking into consideration variation in sampling effort, we estimate that the true incidence of non-monophyly is ∼23%, but with operational factors still being included. Within the operational factors, we separately assessed the frequency of taxonomic limitations (presence of overlooked cryptic and oversplit species) and identification uncertainties. We observed that operational factors are potentially present in more than half (58.6%) of the detected cases of non-monophyly. Furthermore, we observed that in about 20% of non-monophyletic species and entangled species, the lineages involved are either allopatric or parapatric—conditions where species delimitation is inherently subjective and particularly dependent on the species concept that has been adopted. These observations suggest that species-level non-monophyly in COI gene trees is less common than previously supposed, with many cases reflecting misidentifications, the subjectivity of species delimitation or other operational factors.

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We used nuclear 28S rDNA sequence data to estimate the phylogeny of 77 leaf-mining Phyllonorycter (Gracillariidae) moth species, including all 55 British species, feeding on 44 different plant genera. There was strong support for both the monophyly of Phyllonorycter and the placement of the genus Cameraria as its sister group. Host-plant use was mapped onto the moth phylogeny and investigated statistically in several ways. First, we show that the estimated level of cospeciation between leaf miners and their host plants is not greater than expected by chance, despite the physical intimacy of the association. Nevertheless, the pattern of host-plant use is far from random, with closely related Phyllonorycter species generally feeding on closely related plants. However, although Phyllonorycter species from a given host plant tend to form distinct clades, there is also statistical support for multiple independent colonizations of some host-plant taxa (e.g. the order Rosales and the genus Corylus). Despite numerous host shifts, most Phyllonorycter species feed on trees and the few species that attack shrubs or herbs have mostly acquired these habits independently. There is also limited evidence that host shifts to herbs are more likely from shrubs than from trees. Similarly, most species mine the lower surface of leaves but the few upper-surface miners have each evolved the habit independently. Consequently, these shifts to new adaptive zones have not led to substantial radiations.

Gracillariidae are one of the most diverse families of internally feeding insects, and many species are economically important. Study of this family has been hampered by lack of a robust and comprehensive phylogeny. In the present paper, we sequenced up to 22 genes in 96 gracillariid species, representing all previously recognized subfamilies and genus groups, plus 20 outgroups representing other families and superfamilies. Following objective identification and removal of two rogue taxa, two datasets were constructed: dataset 1, which included 12 loci totalling 9927 bp for 94 taxa, and dataset 2, which supplemented dataset 1 with 10 additional loci for 10 taxa, for a total of 22 loci and 16 167 bp. Maximum likelihood analyses strongly supported the monophyly of Gracillariidae and most previously recognized subfamilies and genus groups. On this basis, we propose a new classification consisting of eight subfamilies, four of which are newly recognized or resurrected: Acrocercopinae Kawahara & Ohshima subfam. n.; Gracillariinae Stainton; Lithocolletinae Stainton; Marmarinae Kawahara & Ohshima subfam. n.; Oecophyllembiinae Réal & Balachowsky; Parornichinae Kawahara & Ohshima subfam. n.; Ornixolinae Kuznetzov & Baryshnikova stat. rev.; and Phyllocnistinae Zeller. The subfamily Gracillariinae is restricted to the monophyletic group comprising Gracillaria Haworth and closely related genera. We also formally transfer Acrocercops scriptulata Meyrick to Ornixolinae and use the name Diphtheroptila Vári, creating Diphtheroptila scriptulata comb. n. An exploratory mapping of larval host‐use traits on the phylogeny shows strong conservation of modes of leaf mining but much higher lability of associations with host plant orders and families, suggesting that host shifts could play a significant role in gracillariid diversification. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:942814A2-DE66-41D4-8AB6-FF0B18C87EDB.

Some guidelines are presented for long‐term preservation of insects for non‐traditional systematic studies such as DNA sequencing and internal anatomical research. The main criteria for good DNA preservation appear to be the rapidity with which the DNA is protected from enzymatic and chemical breakdown, and subsequent storage conditions. The immediate post mortem treatment of specimens appears particularly important to the preservation of amplifiable DNA. For storage we recommend 70–100% ethanol at low temperature, deep freezing, and critical point or chemical drying direct from alcohol. For internal anatomy, traditional fixatives, 70% ethanol in a refrigerator, critical point drying or chemical drying are recommended. Cold‐storage in 70% ethanol with or without subsequent critical point drying or chemical drying using hexamethyldisilazane allow both molecular and morphological study.

Knowing the phylogeographic structure of invasive species is important for understanding the underlying processes of invasion. The micromoth Phyllonorycter issikii, whose larvae damage leaves of lime trees Tilia spp., was only known from East Asia. In the last three decades, it has been recorded in most of Europe, Western Russia and Siberia. We used the mitochondrial cytochrome c oxidase subunit I (COI) gene region to compare the genetic variability of P. issikii populations between these different regions. Additionally, we sequenced two nuclear genes (28S rRNA and Histone 3) and run morphometric analysis of male genitalia to probe for the existence of cryptic species.The analysis of COI data of 377 insect specimens collected in 16 countries across the Palearctic revealed the presence of two different lineages: P. issikii and a putative new cryptic Phyllonorycter species distributed in the Russian Far East and Japan. In P. issikii, we identified 31 haplotypes among which 23 were detected in the invaded area (Europe) and 10 were found in its putative native range in East Asia (Russian Far East, Japan, South Korea and China), with only two common haplotypes. The high number of haplotypes found in the invaded area suggest a possible scenario of multiple introductions. One haplotype H1 was dominant (119 individuals, 67.2%), not only throughout its expanding range in Europe and Siberia but, intriguingly, also in 96% of individuals originating from Japan. We detected eight unique haplotypes of P. issikii in East Asia. Five of them were exclusively found in the Russian Far East representing 95% of individuals from that area. The putative new cryptic Phyllonorycter species showed differences from P. issikii for the three studied genes. However, both species are morphologically undistinguishable. They occur in sympatry on the same host plants in Japan (Sendai) and the Russian Far East (Primorsky krai) without evidence of admixture.