Quaternary history and contemporary patterns in a currently expanding species

Environmental and Biogeographic Drivers behind Alpine Plant Thermal Tolerance and Genetic Variation

In alpine ecosystems, elevation broadly functions as a steep thermal gradient, with plant communities exposed to regular fluctuations in hot and cold temperatures. These conditions lead to selective filtering, potentially contributing to species-level variation in thermal tolerance and population-level genetic divergence. Few studies have explored the breadth of alpine plant thermal tolerances across a thermal gradient or the underlying genetic variation thereof. We measured photosystem heat (Tcrit-hot) and cold (Tcrit-cold) thresholds of ten Australian alpine species across elevation gradients and characterised their neutral genetic variation. To reveal the biogeographical drivers of present-day genetic signatures, we also reconstructed temporal changes in habitat suitability across potential distributional ranges. We found intraspecific variation in thermal thresholds, but this was not associated with elevation, nor underpinned by genetic differentiation on a local scale. Instead, regional population differentiation and considerable homozygosity within populations may, in part, be driven by distributional contractions, long-term persistence, and migrations following habitat suitability. Our habitat suitability models suggest that cool-climate-distributed alpine plants may be threatened by a warming climate. Yet, the observed wide thermal tolerances did not reflect this vulnerability. Conservation efforts should seek to understand variations in species-level thermal tolerance across alpine microclimates.

Tracking habitat or testing its suitability? Similar distributional patterns can hide very different histories of persistence versus nonequilibrium dynamics

The expansions and contractions of a species' range in response to temporal changes in selective filters leave genetic signatures that can inform a more accurate reconstruction of their evolutionary history across the landscape. After a long period of continental decline, Australian rainforests settled into localized patterns of contraction or expansion during the climatic fluctuations of the Quaternary. The environmental impacts of recurring glacial and interglacial periods also intensified the arrival of new lineages from the Sunda shelf, and it can be expected that immigrant versus locally persistent taxa responded to environmental challenges in quantifiably different manner. To investigate how such differences impact on species' distribution, we contrast landscape genomic patterns and changes in habitat availability between a species with a long continental history on Doryphora sassafras and a Sunda-derived species (Toona ciliata), across a distributional overlap. Extensive landscape-level homogeneity across chloroplast and nuclear genomes for the Sunda-derived T. ciliata, characterize the genetic signature of a very recent invasion and a rapid southern "exploratory" expansion that had not been previously recorded in the Australian flora (i.e., of Gondwanan origin or Sahul-derived). In contrast, D. sassafras is consistent with other Sahul-derived species characterized by strong geographical divergence and regional differentiation. Interestingly, our findings suggest that admixture between genetically divergent populations during expansion events might be a contributing factor to the successful colonization of novel habitats. Overall, this study identifies some of the mechanisms regulating the rearrangements in species distributions and assemblage composition that follow major environmental shifts, and reminds us how a species' current range might not necessarily define species' habitat preference, with the consequence that estimates of past or future range might not always be reliable.

Evolutionary history and colonization patterns of the wing dimorphic grasshopper Dichroplus vittatus in two Argentinean biomes

Quaternary climate oscillations and modification of the environment by humans have played an important role in shaping species distribution and genetic structure of modern species. Here, population genetic parameters were inferred from the analysis of 168 individuals belonging to 11 populations of the South American grasshopper, Dichroplus vittatus, distributed in two Argentinean Biomes (Grassland and Savanna), by sequencing a 543 bp of the mitochondrial COI gene. Overall, we detected considerable haplotype diversity and low nucleotide diversity. AMOVA analyses showed a significant degree of differentiation among Biomes and between populations. Two major mitochondrial lineages can be distinguished. The haplogroup containing the most common haplotype split 17,000 years BP while the haplogroup including the second most common haplotype has a divergence date of about 11,700 years. Approximate Bayesian Computation (ABC) analyses showed that the palaeodemographic scenario that best fitted our data is consistent with a hypothesis of divergence from an ancestral population and subsequent admixture with Grassland-Savanna (South–North) direction. Our results suggest that populations located in both Biomes would derive from a single ancestral population that colonized the region after the Last Glacial Maximum and Grassland would have a more ancestral origin than Savanna. Further, our results emphasize the importance of human-mediated dispersal in the reconfiguration of genetic diversity of species with potential pest capacity.

Molecular assays to reliably detect and quantify predation on a forest pest in bats faeces

Targeted molecular methods such as conventional PCR (cPCR) and quantitative PCR (qPCR), combined with species-specific primers and probes, are widely applied for pest species detection. Besides, the potential of qPCR to quantify DNA in samples makes it an invaluable molecular tool to infer the predation levels on specific prey by analysing predators’ stools. Nevertheless, studies on the diet of bats failed to find any empirical relationship, and it remains to be evaluated. Thus, we developed and evaluated two species-specific PCR assays to detect and quantify DNA of a major forest pest, the pine processionary, Thaumetopoea pityocampa, in bats’ faeces. Further, we empirically compared a range of different known DNA concentrations (input) of the target species mixed with mocks and bat faecal samples against DNA abundances yielded by qPCR (output) for a quantitative assessment. Overall, cPCR showed a lower detection rate than qPCR, but augmenting the replicate effort from one to three replicates led to a greater increase in the detection rate of the cPCR (from 57 to 80%) than the qPCR (from 90 to 99%). The quantitative experiment results showed a highly significant correlation between the input and output DNA concentrations (t = 10.84, p < 0.001) with a mean slope value of 1.05, indicating the accuracy of our qPCR assay to estimate DNA abundance of T. pityocampa in bat faeces. The framework of this study can be taken as a model to design similar assays applicable to other species of interest, such as agricultural pests or insects of public health concern.

The phylogeny, phylogeography, and diversification history of the westernmost Asian cobra (Serpentes: Elapidae: Naja oxiana) in the Trans-Caspian region

We conducted a comprehensive analysis of the phylogenetic, phylogeographic, and demographic relationships of Caspian cobra (Naja oxiana; Eichwald, 1831) populations based on a concatenated dataset of two mtDNA genes (cyt b and ND4) across the species' range in Iran, Afghanistan, and Turkmenistan, along with other members of Asian cobras (i.e., subgenus Naja Laurenti, 1768). Our results robustly supported that the Asiatic Naja are monophyletic, as previously suggested by other studies. Furthermore, N. kaouthia and N. sagittifera were recovered as sister taxa to each other, and in turn sister clades to N. oxiana. Our results also highlighted the existence of a single major evolutionary lineage for populations of N. oxiana in the Trans-Caspian region, suggesting a rapid expansion of this cobra from eastern to western Asia, coupled with a rapid range expansion from east of Iran toward the northeast. However, across the Iranian range of N. oxiana, subdivision of populations was not supported, and thus, a single evolutionary significant unit is proposed for inclusion in future conservation plans in this region.

Coding-Complete Genome Sequence of a Partitivirus Isolated from Pine Processionary Moth Eggs

Two coding-complete nucleotide sequences of a partitivirus (family Partitiviridae) were discovered in transcriptomic data sets obtained from eggs of the Lepidoptera Thaumetopoea pityocampa. Each segment encodes a single open reading frame, and these two segments are predicted to encode an RNA-dependent RNA polymerase and a coat protein, respectively.

Two coding-complete nucleotide sequences of a partitivirus (family Partitiviridae) were discovered in transcriptomic data sets obtained from eggs of the Lepidoptera Thaumetopoea pityocampa. Each segment encodes a single open reading frame, and these two segments are predicted to encode an RNA-dependent RNA polymerase and a coat protein, respectively.

Coding-Complete Genome Sequences of an Iteradensovirus and an Alphapermutotetra-Like Virus Identified from the Pine Processionary Moth (Thaumetopoea pityocampa) in Portugal

The coding-complete nucleotide sequences of an iteradensovirus (family Parvoviridae) and an alphapermutotetra-like virus (family Permutotetraviridae) were discovered from transcriptomic data sets obtained from Thaumetopoea pityocampa larvae collected in Portugal. Each of the coding-complete genome sequences of these viruses contain three main open reading frames (ORFs).

The coding-complete genome sequences of an iteradensovirus (family Parvoviridae) and an alphapermutotetra-like virus (family Permutotetraviridae) were discovered from transcriptomic data sets obtained from Thaumetopoea pityocampa larvae collected in Portugal. Each of the coding-complete genome sequences of these viruses contains three main open reading frames (ORFs).

Improving climate suitability for Bemisia tabaci in East Africa is correlated with increased prevalence of whiteflies and cassava diseases

Projected climate changes are thought to promote emerging infectious diseases, though to date, evidence linking climate changes and such diseases in plants has not been available. Cassava is perhaps the most important crop in Africa for smallholder farmers. Since the late 1990’s there have been reports from East and Central Africa of pandemics of begomoviruses in cassava linked to high abundances of whitefly species within the Bemisia tabaci complex. We used CLIMEX, a process-oriented climatic niche model, to explore if this pandemic was linked to recent historical climatic changes. The climatic niche model was corroborated with independent observed field abundance of B. tabaci in Uganda over a 13-year time-series, and with the probability of occurrence of B. tabaci over 2 years across the African study area. Throughout a 39-year climate time-series spanning the period during which the pandemics emerged, the modelled climatic conditions for B. tabaci improved significantly in the areas where the pandemics had been reported and were constant or decreased elsewhere. This is the first reported case where observed historical climate changes have been attributed to the increase in abundance of an insect pest, contributing to a crop disease pandemic.

Host use diversification during range shifts shapes global variation in Lepidopteran dietary breadth

Niche breadths tend to be greater at higher latitudes. This pattern is frequently assumed to emerge from the cumulative effects of multiple, independent local adaptation events along latitudinal environmental gradients, although evidence that generalization is more beneficial at higher-latitude locations remains equivocal. Here I propose an alternative hypothesis: that latitudinal variation in niche breadths emerges as a non-adaptive consequence of range shift dynamics. Based on analysis of a global dataset comprising more than 6,934 globally distributed dietary records from 4,410 Lepidopteran species, this hypothesis receives robust support. Population-level dietary niche breadths are better explained by the relative position of the population within its geographic range and the species' poleward range extent than by the latitude of diet observation. Broader diets are observed closer to poleward range limits and in species that have attained higher latitudes. Moreover, latitudinal variation in diet breadth is more prominent within and among species undergoing rapid, contemporary range shifts than for species with more stable ranges. Together these results suggest that latitudinal patterns in niche breadth represent a transient and emergent property of recent geographic range dynamics and need not require underlying gradients in selective agents or fitness trade-offs. The results have wide-ranging implications for global ecology and for anticipating changes in host use during ongoing distributional shifts of pests and disease vectors.

From refugia to contact: Pine processionary moth hybrid zone in a complex biogeographic setting

Contact zones occur at the crossroad between specific dispersal routes and are facilitated by biogeographic discontinuities. Here, we focused on two Lepidoptera sister species that come in contact near the Turkish Straits System (TSS). We aimed to infer their phylogeographic histories in the Eastern Mediterranean and finely analyze their co-occurrence and hybridization patterns in this biogeographic context. We used molecular mitochondrial and nuclear markers to study 224 individuals from 42 localities. We used discordances between markers and complementary assignment methods to identify and map hybrids and parental individuals. We confirmed the parapatric distribution of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) in the west and Thaumetopoea wilkinsoni in the east and identified a narrow contact zone. We identified several glacial refugia of T. wilkinsoni in southern Turkey with a strong east-west differentiation in this species. Unexpectedly, T. pityocampa crossed the TSS and occur in northern Aegean Turkey and some eastern Greek islands. We found robust evidence of introgression between the two species in a restricted zone in northwestern Turkey, but we did not identify any F1 individuals. The identified hybrid zone was mostly bimodal. The distributions and genetic patterns of the studied species were strongly influenced both by the Quaternary climatic oscillations and the complex geological history of the Aegean region. T. pityocampa and T. wilkinsoni survived the last glacial maximum in disjoint refugia and met in western Turkey at the edge of the recolonization routes. Expanding population of T. wilkinsoni constrained T. pityocampa to the western Turkish shore. Additionally, we found evidence of recurrent introgression by T. wilkinsoni males in several T. pityocampa populations. Our results suggest that some prezygotic isolation mechanisms, such as differences in timing of the adult emergences, might be a driver of the isolation between the sister species.

New Data on the Range Expansion of the Thaumetopoea pityocampa (Lepidoptera: Notodontidae) 'ENA clade' in Greece: The Role of Bacterial Endosymbionts

The pine processionary moth, Thaumetopoea pityocampa (Denis and Schiffermüller), is an important insect in the Mediterranean region, as it defoliates pines and its urticating hairs can cause allergic reactions in humans and animals. Moreover, this species exhibits an interesting genetic structure as recently a distinct East-North African mtDNA lineage ('ENA clade') has been described. This clade has been recently detected in Greek populations where it has currently expanded its range by replacing the 'endemic' T. pityocampa lineages. Here, we report new data on the rapid spread of 'ENA clade' in the Greek island Evoia in only a few years. As the underlying mechanisms of the 'ENA clade' range expansion has not been studied so far, we screened T. pityocampa for an infection with the heritable bacterial endosymbionts Wolbachia (Bacteria: Anaplasmataceae), Cardinium (Bacteria: Bacteroidaceae), Rickettsia (Bacteria: Rickettsiaceae) and Spiroplasma (Bacteria: Spiroplasmataceae). These bacteria can manipulate the reproduction of infected hosts, something that could potentially explain the rapid spread of 'ENA clade' lineage. Therefore, we screened 28 individuals that exhibited T. pityocampa 'ENA clade' and 'endemic' T. pityocampa haplotypes from nine populations scattered all over Greece. None of them was infected with any of the four endosymbionts, suggesting that these bacteria do not cause reproductive manipulations in T. pityocampa lineages and, thus, other factors should be explored in future research efforts.

Pine Pitch Canker and Insects: Regional Risks, Environmental Regulation, and Practical Management Options

Pine pitch canker (PPC), caused by the pathogenic fungus Fusarium circinatum (Nirenberg and O’ Donnell), is a serious threat to pine forests globally. The recent introduction of the pathogen to Southern Europe and its spread in Mediterranean region is alarming considering the immense ecological and economic importance of pines in the region. Pines in forests and nurseries can be infected, resulting in severe growth losses and mortality. The pathogen is known to spread in plants for planting and in seeds, and results from recent studies have indicated that F. circinatum may also spread through phoretic associations with certain insects. With this review, we aim to expand the current understanding of the risk of insect-mediated spread of PPC in different parts of Europe. Through the joint action of a multinational researcher team, we collate the existing information about the insect species spectrum in different biogeographic conditions and scrutinize the potential of these insects to transmit F. circinatum spores in forests and nurseries. We also discuss the impact of environmental factors and forest management in this context. We present evidence for the existence of a high diversity of insects with potential to weaken pines and disseminate PPC in Europe, including several common beetle species. In many parts of Europe, temperatures are projected to rise, which may promote the activity of several insect species, supporting multivoltinism and thus, further amplifying the risk of insect-mediated dissemination of PPC. Integrated pest management (IPM) solutions that comply with forest management practices need to be developed to reduce this risk. We recommend careful monitoring of insect populations as the basis for successful IPM. Improved understanding of environmental control of the interaction between insects, the pathogen, and host trees is needed in order to support development of bio-rational strategies to safeguard European pine trees and forests against F. circinatum in future.

Identification and analysis of the complete mitochondrial genome of Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

The mitochondrial genome (mitogenome) provides important information for phylogenetic analysis and understanding evolutionary origins. Thaumetopoea pityocampa is a forest pest that harms nearly all cedar and pine species. In this study, the T. pityocampa mitochondrial genome was sequenced, assembled, and annotated. The sequence length of the genome was found to be 15,737 bp, containing 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, and an A + T-rich region compared with the genomes of other lepidopterans. The overall nucleotide composition is: 37.3% T, 40.5% A, 14.6% C, and 7.6% G, demonstrating an AT bias (A + T: 77.8%). Our phylogenetic tree analysis results showed that T. pityocampa and Ochrogaster lunifer were the most similar species, with the closest evolutionary distance. The mitogenome sequence determined in this study will contribute to improved understanding of Notodontidae evolution.

Global phylogeography reveals the origin and the evolutionary history of the gypsy moth (Lepidoptera, Erebidae)

We examined the global phylogeography of gypsy moth (Lymantria dispar L.) using molecular data based on mitochondrial and nuclear genes. Populations from all biogeographic regions of the native and introduced range of L. dispar, were sampled to fully document intraspecific and subspecies variation, identify potential cryptic species, and to clarify the relationships among major phylogeographic lineages. We recovered three major mtDNA lineages of L. dispar: Transcaucasia; East Asia + Japan; and Europe + Central Asia. The circumscription of these lineages is only partially consistent with the current taxonomic concept (i.e., L. dispar dispar; L. dispar asiatica; L. dispar japonica), with the following important discrepancies: (1) north-central Asian populations, including topotypical populations of L. dispar asiatica, may be more closely related to European rather than Asian segregates, which would require the synonymization of the taxon asiatica and establishment of a new name; (2) the Japanese populations (L. d. japonica) are not distinct from east Asian populations; (3) the presence of a distinct, unnamed mitogenomic lineage endemic to the Trancaucasus region. We demonstrated that the population from Transcaucasia contains the highest mitochondrial haplotype diversity among L. dispar, potentially indicative of an ancestral area for the entire dispar-group. Our study corroborates the endemic Hokkaido, Japan taxon Lymantria umbrosa (Butler) as the sister group to all other L. dispar populations, but the applicability of the names umbrosa versus hokkaidoensis Goldschmidt needs to be re-evaluated. The ancestral area analysis suggest that Japan was likely colonized via Sakhalin ∼1 Mya, in contrast to previous studies which have suggested colonization of the Japanese archipelago via the Korean Peninsula. Lastly, mitogenomic variation within L. dispar is incongruent with phylogenies based on nuclear DNA, as nDNA gene phylogenies did not recover the three major mtDNA lineages, and also failed to recover L. dispar and L. umbrosa as reciprocally monophyletic.

Winter temperature predicts prolonged diapause in pine processionary moth species across their geographic range

Prolonged diapause occurs in a number of insects and is interpreted as a way to evade adverse conditions. The winter pine processionary moths (Thaumetopoea pityocampa and Th. wilkinsoni) are important pests of pines and cedars in the Mediterranean region. They are typically univoltine, with larvae feeding across the winter, pupating in spring in the soil and emerging as adults in summer. Pupae may, however, enter a prolonged diapause with adults emerging one or more years later. We tested the effect of variation in winter temperature on the incidence of prolonged diapause, using a total of 64 individual datasets related to insect cohorts over the period 1964-2015 for 36 sites in seven countries, covering most of the geographic range of both species. We found high variation in prolonged diapause incidence over their ranges. At both lower and upper ends of the thermal range in winter, prolonged diapause tended to be higher than at intermediate temperatures. Prolonged diapause may represent a risk-spreading strategy to mitigate climate uncertainty, although it may increase individual mortality because of a longer exposure to mortality factors such as predation, parasitism, diseases or energy depletion. Climate change, and in particular the increase of winter temperature, may reduce the incidence of prolonged diapause in colder regions whereas it may increase it in warmer ones, with consequences for population dynamics.

Revisiting the Distribution of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) and T. pityocampa ENA Clade in Greece

In the present work, we sampled individuals of the processionary pine moth, Thaumetopoea pityocampa (Denis and Schiffermüller; Lepidoptera: Notodontidae) from different areas of Greece between 2014 and 2016. These samples were sequenced for a 760-bp long mtDNA COI locus and the haplotypes retrieved clearly showed that the occurrence of T. pityocampa in Greece is being considerably restricted, with only 8 individuals out of the 221 exhibiting T. pityocampa haplotypes and the rest being identified as T. pityocampa ENA clade haplotypes. To that, one haplotype in particular exhibited the highest abundance and broadest geographic distribution, occurring both in mainland and on islands. Our data suggest a rather recent and rapid population expansion of the ENA clade in Greece and a concomitant recent displacement of T. pityocampa. It thus seems that the relation between T. pityocampa and T. pityocampa ENA clade needs to be further and thorough analyzed before the taxonomic status of T. pityocampa ENA clade can be concluded with confidence.

Draft genome and reference transcriptomic resources for the urticating pine defoliator Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

The pine processionary moth Thaumetopoea pityocampa (Lepidoptera: Notodontidae) is the main pine defoliator in the Mediterranean region. Its urticating larvae cause severe human and animal health concerns in the invaded areas. This species shows a high phenotypic variability for various traits, such as phenology, fecundity and tolerance to extreme temperatures. This study presents the construction and analysis of extensive genomic and transcriptomic resources, which are an obligate prerequisite to understand their underlying genetic architecture. Using a well-studied population from Portugal with peculiar phenological characteristics, the karyotype was first determined and a first draft genome of 537 Mb total length was assembled into 68,292 scaffolds (N50 = 164 kb). From this genome assembly, 29,415 coding genes were predicted. To circumvent some limitations for fine-scale physical mapping of genomic regions of interest, a 3X coverage BAC library was also developed. In particular, 11 BACs from this library were individually sequenced to assess the assembly quality. Additionally, de novo transcriptomic resources were generated from various developmental stages sequenced with HiSeq and MiSeq Illumina technologies. The reads were de novo assembled into 62,376 and 63,175 transcripts, respectively. Then, a robust subset of the genome-predicted coding genes, the de novo transcriptome assemblies and previously published 454/Sanger data were clustered to obtain a high-quality and comprehensive reference transcriptome consisting of 29,701 bona fide unigenes. These sequences covered 99% of the cegma and 88% of the busco highly conserved eukaryotic genes and 84% of the busco arthropod gene set. Moreover, 90% of these transcripts could be localized on the draft genome. The described information is available via a genome annotation portal (http://bipaa.genouest.org/sp/thaumetopoea_pityocampa/).

Metabarcoding for the parallel identification of several hundred predators and their prey: Application to bat species diet analysis

Assessing diet variability is of main importance to better understand the biology of bats and design conservation strategies. Although the advent of metabarcoding has facilitated such analyses, this approach does not come without challenges. Biases may occur throughout the whole experiment, from fieldwork to biostatistics, resulting in the detection of false negatives, false positives or low taxonomic resolution. We detail a rigorous metabarcoding approach based on a short COI minibarcode and two-step PCR protocol enabling the "all at once" taxonomic identification of bats and their arthropod prey for several hundreds of samples. Our study includes faecal pellets collected in France from 357 bats representing 16 species, as well as insect mock communities that mimic bat meals of known composition, negative and positive controls. All samples were analysed using three replicates. We compare the efficiency of DNA extraction methods, and we evaluate the effectiveness of our protocol using identification success, taxonomic resolution, sensitivity and amplification biases. Our parallel identification strategy of predators and prey reduces the risk of mis-assigning prey to wrong predators and decreases the number of molecular steps. Controls and replicates enable to filter the data and limit the risk of false positives, hence guaranteeing high confidence results for both prey occurrence and bat species identification. We validate 551 COI variants from arthropod including 18 orders, 117 family, 282 genus and 290 species. Our method therefore provides a rapid, resolutive and cost-effective screening tool for addressing evolutionary ecological issues or developing "chirosurveillance" and conservation strategies.

A total evidence phylogeny for the processionary moths of the genus Thaumetopoea (Lepidoptera: Notodontidae: Thaumetopoeinae)

Processionary moths belong to a group of about 100 species well known for their social behaviour and their urticating systems. The genus Thaumetopoea s.l. includes about 15 species and has been divided into three genera (Helianthocampa, Thaumetopoea s.s., and Traumatocampa) in the last revision, based on key morphological features of the adults and on the host plants of the larvae. We performed a total evidence approach to resolve the phylogeny of the genus Thaumetopoea s.l., analysing all valid taxa included in this group, plus a broad array of close relatives. Thaumetopoea was monophyletic and supported by several apomorphies. Further subclades corroborated by synapomorphies were identified. Our phylogeny suggests that Thaumetopoea must be regarded as a single genus. The mapping of key life history traits on the total evidence tree allowed us to sketch a plausible identikit of the Thaumetopoea ancestor and to track the evolution of the genus. The ancestor originated in the eastern Mediterranean area, and used broadleaved host plants. Subsequently, a switch to conifers occurred, just once, in a large subclade. The ancestor pupated in the soil, like several current species, but in a few taxa this trait was lost, together with the related morphological adaptations.

Evaluation of Pheromone Trap Devices for the Capture of Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) in Southern Europe

The development of reliable monitoring techniques can offer valuable sources of knowledge on the control of Thaumetopoea pityocampa (Denis and Schiffermüller) (Lepidoptera: Thaumetopoeidae). Nevertheless, there is a knowledge gap on the simultaneous large-scale monitoring of T. pityocampa male adult population by using novel trap devices. Thus, the influence of type of trap device on the capture of male adults of T. pityocampa was evaluated in four areas with pine trees in southern Europe; two in Greece (Thessaly and Attica), one in Italy (Molise), and one in Spain (Valencia). Six different novel trap devices, i.e., Prototype 1, Prototype 2, Prototype 3, Prototype 4, Prototype 5, and Prototype 6, were tested during 2015 between July and November. In general, the male adult catches lasted longer in the two sites of Greece compared with Molise and Valencia. Hence, in Thessaly, captures started in early August and remained at high levels until late September. In Attica, captures started in mid-August and lasted until early November. In contrast, for both Molise and Valencia, most of the male adults were captured in August, while male adult catches were recorded until September. From the trap devices tested, Prototype 1 was found superior than the other devices, regardless of the area, with the exception of Valencia, where there were no differences in the overall captures among Prototype 1, Prototype 5, and Prototype 6. In most of the combinations tested, there was a positive and significant correlation among captures of T. pityocampa in pairs of different trap devices, indicating that most of them gave similar population fluctuations. Our results suggest that Prototype 1 should be selected for the monitoring of T. pityocampa male adult population.

Processionary Moths and Associated Urtication Risk: Global Change-Driven Effects

Processionary moths carry urticating setae, which cause health problems in humans and other warm-blooded animals. The pine processionary moth Thaumetopoea pityocampa has responded to global change (climate warming and increased global trade) by extending its distribution range. The subfamily Thaumetopoeinae consists of approximately 100 species. An important question is whether other processionary moth species will similarly respond to these specific dimensions of global change and thus introduce health hazards into new areas. We describe, for the first time, how setae are distributed on different life stages (adult, larva) of major groups within the subfamily. Using the available data, we conclude that there is little evidence that processionary moths as a group will behave like T. pityocampa and expand their distributional range. The health problems caused by setae strongly relate to population density, which may, or may not, be connected to global change.

Are the metabolomic responses to folivory of closely related plant species linked to macroevolutionary and plant-folivore coevolutionary processes?

The debate whether the coevolution of plants and insects or macroevolutionary processes (phylogeny) is the main driver determining the arsenal of molecular defensive compounds of plants remains unresolved. Attacks by herbivorous insects affect not only the composition of defensive compounds in plants but also the entire metabolome. Metabolomes are the final products of genotypes and are constrained by macroevolutionary processes, so closely related species should have similar metabolomic compositions and may respond in similar ways to attacks by folivores. We analyzed the elemental compositions and metabolomes of needles from three closely related Pinus species with distant coevolutionary histories with the caterpillar of the processionary moth respond similarly to its attack. All pines had different metabolomes and metabolic responses to herbivorous attack. The metabolomic variation among the species and the responses to folivory reflected their macroevolutionary relationships, with P. pinaster having the most divergent metabolome. The concentrations of terpenes were in the attacked trees supporting the hypothesis that herbivores avoid plant individuals with higher concentrations. Our results suggest that macroevolutionary history plays important roles in the metabolomic responses of these pine species to folivory, but plant-insect coevolution probably constrains those responses. Combinations of different evolutionary factors and trade-offs are likely responsible for the different responses of each species to folivory, which is not necessarily exclusively linked to plant-insect coevolution.

Genetic differentiation of the pine processionary moth at the southern edge of its range: contrasting patterns between mitochondrial and nuclear markers

The pine processionary moth (Thaumetopoea pityocampa) is an important pest of coniferous forests at the southern edge of its range in Maghreb. Based on mitochondrial markers, a strong genetic differentiation was previously found in this species between western (pityocampa clade) and eastern Maghreb populations (ENA clade), with the contact zone between the clades located in Algeria. We focused on the moth range in Algeria, using both mitochondrial (a 648 bp fragment of the tRNA-cox2) and nuclear (11 microsatellite loci) markers. A further analysis using a shorter mtDNA fragment and the same microsatellite loci was carried out on a transect in the contact zone between the mitochondrial clades. Mitochondrial diversity showed a strong geographical structure and a well-defined contact zone between the two clades. In particular, in the pityocampa clade, two inner subclades were found whereas ENA did not show any further structure. Microsatellite analysis outlined a different pattern of differentiation, with two main groups not overlapping with the mitochondrial clades. The inconsistency between mitochondrial and nuclear markers is probably explained by sex-biased dispersal and recent afforestation efforts that have bridged isolated populations.

Genetic diversity of Thaumetopoea pityocampa in Greece: the role of Quaternary changes in Aegean Sea

Thaumetopoea pityocampa, the winter pine processionary moth, is one of the most important pests of pine trees in the Mediterranean region. To learn more about the refugial areas within the greater refugium of Greece, samples from 15 local populations were collected. Analysis of the Cytochrome Oxidase I region identified 15 haplotypes. One strongly supported clade was found, separating the Aegean island of Lesvos from the mainland populations. Mdiv analysis showed that this clade diverged from the general clade 155,000 y.a., suggesting the sea level changes during the Quaternary Period as a possible reason for its seclusion. Additionally, comparisons with similar studies in this region revealed a possible colonization of the eastern Aegean islands from the Turkish mainland rather than from Greece. However, no strong isolation-by-distance events were detected among the mainland populations, which could be attributed to the joint effect of regular gene flow and the lack of insurmountable geographic barriers. Finally, regarding population structure, Bayesian analysis as well as neutrality tests pointed towards an ongoing population expansion which verifies the potential invasiveness of this pest species, something that will have to be dealt with under the influence of climate change.

Genetic diversity and host alternation of the egg parasitoid Ooencyrtus pityocampae between the pine processionary moth and the caper bug

The increased use of molecular tools for species identification in recent decades revealed that each of many apparently generalist parasitoids are actually a complex of morphologically similar congeners, most of which have a rather narrow host range. Ooencyrtus pityocampae (OP), an important egg parasitoid of the pine processionary moth (PPM), is considered a generalist parasitoid. OP emerges from PPM eggs after winter hibernation, mainly in spring and early summer, long before the eggs of the next PPM generation occurs. The occurrence of OP in eggs of the variegated caper bug (CB) Stenozygum coloratum in spring and summer suggests that OP populations alternate seasonally between PPM and CB. However, the identity of OP population on CB eggs seemed uncertain; unlike OP-PPM populations, the former displayed apparently high male/female ratios and lack of attraction to the PPM sex pheromone. We studied the molecular identities of the two populations since the morphological identification of the genus Ooencyrtus, and OP in particular, is difficult. Sequencing of COI and ITS2 DNA fragments and AFLP analysis of individuals from both hosts revealed no apparent differences between the OP-PPM and the OP-CB populations for both the Israeli and the Turkish OPs, which therefore supported the possibility of host alternation. Sequencing data extended our knowledge of the genetic structure of OP populations in the Mediterranean area, and revealed clear separation between East and West Mediterranean populations. The overall level of genetic diversity was rather small, with the Israeli population much less diverse than all others; possible explanations for this finding are discussed. The findings support the possibility of utilizing the CB and other hosts for enhancing biological control of the PPM.

Temporal relationship between genetic and warning signal variation in the aposematic wood tiger moth (Parasemia plantaginis)

Many plants and animals advertise unpalatability through warning signals in the form of colour and shape. Variation in warning signals within local populations is not expected because they are subject to directional selection. However, mounting evidence of warning signal variation within local populations suggests that other selective forces may be acting. Moreover, different selective pressures may act on the individual components of a warning signal. At present, we have a limited understanding about how multiple selection processes operate simultaneously on warning signal components, and even less about their temporal and spatial dynamics. Here, we examined temporal variation of several wing warning signal components (colour, UV-reflectance, signal size and pattern) of two co-occurring colour morphs of the aposematic wood tiger moth (Parasemia plantaginis). Sampling was carried out in four geographical regions over three consecutive years. We also evaluated each morph's temporal genetic structure by analysing mitochondrial sequence data and nuclear microsatellite markers. Our results revealed temporal differences between the morphs for most signal components measured. Moreover, variation occurred differently in the fore- and hindwings. We found no differences in the genetic structure between the morphs within years and regions, suggesting single local populations. However, local genetic structure fluctuated temporally. Negative correlations were found between variation produced by neutrally evolving genetic markers and those of the different signal components, indicating a non-neutral evolution for most warning signal components. Taken together, our results suggest that differential selection on warning signal components and fluctuating population structure can be one explanation for the maintenance of warning signal variation in this aposematic species.

A strong 'filter' effect of the East China Sea land bridge for East Asia's temperate plant species: inferences from molecular phylogeography and ecological niche modelling of Platycrater arguta (Hydrangeaceae)

Background

In East Asia, an increasing number of studies on temperate forest tree species find evidence for migration and gene exchange across the East China Sea (ECS) land bridge up until the last glacial maximum (LGM). However, it is less clear when and how lineages diverged in this region, whether in full isolation or in the face of post-divergence gene flow. Here, we investigate the effects of Quaternary changes in climate and sea level on the evolutionary and demographic history of Platycrater arguta, a rare temperate understorey shrub with disjunct distributions in East China (var. sinensis) and South Japan (var. arguta). Molecular data were obtained from 14 P. arguta populations to infer current patterns of molecular structure and diversity in relation to past (Last Interglacial and Last Glacial Maximum) and present distributions based on ecological niche modelling (ENM). A coalescent-based isolation-with-migration (IM) model was used to estimate lineage divergence times and population demographic parameters.

Results

Combining information from nuclear/chloroplast sequence data with nuclear microsatellites, our IM analyses identify the two varieties as genetically distinct units that evolved in strict allopatry since the mid-Pleistocene, c. 0.89 (0.51–1.2) Ma. Together with Bayesian Skyeline Plots, our data further suggest that both lineages experienced post-divergence demographic growth, followed by refugial isolation, divergence, and in the case of var. arguta post-glacial admixture. However, past species distribution modelling indicates that the species’ overall distribution has not greatly changed over the last glacial cycles.

Conclusions

Our findings highlight the important influence of ancient sea-level changes on the diversification of East Asia’s temperate flora. Implicitly, they challenge the notion of general temperate forest expansion across the ECS land bridge, demonstrating instead its ‘filter’ effect owing to an unsuitable environment for certain species and their biological (e.g., recruitment) properties.

Comparative analysis of two phenologically divergent populations of the pine processionary moth (Thaumetopoea pityocampa) by de novo transcriptome sequencing

The pine processionary moth Thaumetopoea pityocampa is a Mediterranean lepidopteran defoliator that experiences a rapid range expansion towards higher latitudes and altitudes due to the current climate warming. Its phenology - the time of sexual reproduction - is certainly a key trait for the local adaptation of the processionary moth to climatic conditions. Moreover, an exceptional case of allochronic differentiation was discovered ca. 15 years ago in this species. A population with a shifted phenology (the summer population, SP) co-exists near Leiria, Portugal, with a population following the classical cycle (the winter population, WP). The existence of this population is an outstanding opportunity to decipher the genetic bases of phenology. No genomic resources were so far available for T. pityocampa. We developed a high-throughput sequencing approach to build a first reference transcriptome, and to proceed with comparative analyses of the sympatric SP and WP. We pooled RNA extracted from whole individuals of various developmental stages, and performed a transcriptome characterisation for both populations combining Roche 454-FLX and traditional Sanger data. The obtained sequences were clustered into ca. 12,000 transcripts corresponding to 9265 unigenes. The mean transcript coverage was 21.9 reads per bp. Almost 70% of the de novo assembled transcripts displayed significant similarity to previously published proteins and around 50% of the transcripts contained a full-length coding region. Comparative analyses of the population transcriptomes allowed to investigate genes specifically expressed in one of the studied populations only, and to identify the most divergent homologous SP/WP transcripts. The most divergent pairs of transcripts did not correspond to obvious phenology-related candidate genes, and 43% could not be functionally annotated. This study provides the first comprehensive genome-wide resource for the target species T. pityocampa. Many of the assembled genes are orthologs of published Lepidoptera genes, which allows carrying out gene-specific re-sequencing. Data mining has allowed the identification of SNP loci that will be useful for population genomic approaches and genome-wide scans of population differentiation to identify signatures of selection.

Migration and dispersal may drive to high genetic variation and significant genetic mixing: the case of two agriculturally important, continental hoverflies (Episyrphus balteatus and Sphaerophoria scripta)

Population structure of pests and beneficial species is an important issue when designing management strategies to optimize ecosystem services. In this study, we investigated for the first time the population structure at a continental scale of two migratory species of hoverflies providing both pest regulation and pollination services [Episyrphus balteatus and Sphaerophoria scripta (Diptera: Syrphidae)]. To achieve this objective, we used two sets of 12 species-specific microsatellite markers on a large-scale sampling from all over Europe. Our findings showed a high level of genetic mixing resulting in a lack of genetic differentiation at a continental scale and a great genetic diversity in the two species. All the pairwise FST values between European localities were less 0.05 in the two species. These low values reflect a large-scale genetic mixing probably caused by the existence of frequent migratory movements in the two species. Mantel tests revealed isolation-by-distance pattern on the East-West axis, but not on the North-South axis. This isolation-by-distance pattern confirms the existence of North-South migratory movements in both directions and suggests an important step by step dispersal. Population features shown by this study are common in invasive species and pests, but are not often observed in beneficial species. They reflect great colonization abilities and a high adaptive potential when dealing with a changing environment. Our results highlight the two studied species as particularly interesting beneficial insects for pollination and pest predation in the current context of global change.

Stepping-stone expansion and habitat loss explain a peculiar genetic structure and distribution of a forest insect

It is challenging to unravel the history of organisms with highly scattered populations. Such species may have fragmented distributions because extant populations are remnants of a previously more continuous range, or because the species has narrow habitat requirements in combination with good dispersal capacity (naturally or vector borne). The northern pine processionary moth Thaumetopoea pinivora has a scattered distribution with fragmented populations in two separate regions, northern and south-western Europe. The aims of this study were to explore the glacial and postglacial history of T. pinivora, and add to the understanding of its current distribution and level of contemporary gene flow. We surveyed published records of its occurrence and analysed individuals from a representative subset of populations across the range. A 633 bp long fragment of the mtDNA COI gene was sequenced and nine polymorphic microsatellite loci were genotyped. Only nine nucleotide sites were polymorphic in the COI gene and 90% of the individuals from across its whole range shared the same haplotype. The microsatellite diversity gradually declined towards the north, and unique alleles were found in only three of the northern and three of southern sites. Genetic structuring did not indicate complete isolation among regions, but an increase of genetic isolation by geographic distance. Approximate Bayesian model choice suggested recent divergence during the postglacial period, but glacial refugia remain unidentified. The progressive reduction of suitable habitats is suggested to explain the genetic structure of the populations and we suggest that T. pinivora is a cold-tolerant relict species, with situation-dependent dispersal.

Host and phenology shifts in the evolution of the social moth genus Thaumetopoea

The genus Thaumetopoea contains the processionary moths, a group of lepidopteran associated with forest trees, well known for the social behaviour of the larvae and for carrying urticating setae. The taxonomy of the genus is partly unresolved and a phylogenetic approach is lacking. The goal of this work is to produce a phylogeny for Thaumetopoea and to identify the main traits driving the evolution of this group. Eighteen mitochondrial and three nuclear genes were fully/partly sequenced. Markers were aligned and analysed singularly or in various combinations. Phylogenetic analyses were performed according to maximum likelihood and Bayesian inference methods. Trees obtained from largest data sets provided identical topologies that received strong statistical support. Three main clades were identified within Thaumetopoea and were further supported by several signatures located in the mitochondrial tRNAs and intergenic spacers. The reference topology was used to investigate the evolution of life history traits related to biogeography, host plant, ecology, and morphology. A multigenic approach allowed to produce a robust phylogenetic analysis of the genus Thaumetopoea, with the identification of three major clades linked to different ecological and life history traits. The first clade is associated with Angiosperm host plants and has a fast spring development of larvae on young foliage. The other clades have originated by one event of host plant shift to Gymnosperm Pinaceae, which implied a longer larval developmental time due to the lower nutritional quality of leaves. These clades showed different adaptations to such a constraint, the first with a switch of larval feeding to cold season (winter pine processionary moths), and the second with a retraction to high altitude and latitude and a development cycle extended over two years (summer pine processionary moths). Recent global warming is affecting all species and seems able to further shape the evolution of the group.

Host and phenology shifts in the evolution of the social moth genus Thaumetopoea

The genus Thaumetopoea contains the processionary moths, a group of lepidopteran associated with forest trees, well known for the social behaviour of the larvae and for carrying urticating setae. The taxonomy of the genus is partly unresolved and a phylogenetic approach is lacking. The goal of this work is to produce a phylogeny for Thaumetopoea and to identify the main traits driving the evolution of this group. Eighteen mitochondrial and three nuclear genes were fully/partly sequenced. Markers were aligned and analysed singularly or in various combinations. Phylogenetic analyses were performed according to maximum likelihood and Bayesian inference methods. Trees obtained from largest data sets provided identical topologies that received strong statistical support. Three main clades were identified within Thaumetopoea and were further supported by several signatures located in the mitochondrial tRNAs and intergenic spacers. The reference topology was used to investigate the evolution of life history traits related to biogeography, host plant, ecology, and morphology. A multigenic approach allowed to produce a robust phylogenetic analysis of the genus Thaumetopoea, with the identification of three major clades linked to different ecological and life history traits. The first clade is associated with Angiosperm host plants and has a fast spring development of larvae on young foliage. The other clades have originated by one event of host plant shift to Gymnosperm Pinaceae, which implied a longer larval developmental time due to the lower nutritional quality of leaves. These clades showed different adaptations to such a constraint, the first with a switch of larval feeding to cold season (winter pine processionary moths), and the second with a retraction to high altitude and latitude and a development cycle extended over two years (summer pine processionary moths). Recent global warming is affecting all species and seems able to further shape the evolution of the group.

Morphology and phylogeny of Reticulitermes sp. (Isoptera, Rhinotermitidae) from Cyprus

Taxonomy and phylogeny of termites of the genus Reticulitermes in central and eastern Mediterranean lands are poorly understood, partly due to insufficient sampling. This study aims to contribute to the knowledge of east Mediterranean termites by presenting morphological and molecular data on Reticulitermes from Cyprus. Samples from 15 colonies were collected throughout the island. Qualitative and quantitative morphological characters were analyzed for alate and soldier castes. Partial sequences of the mitochondrial genes COII and 16S were used to evaluate genetic diversity of Cypriot colonies and to determine their phylogenetic relationships with taxa from central and eastern Mediterranean areas. Cypriot alates have some morphological features in common with the Israeli R. clypeatus: an enlarged postclypeus and a wide unpigmented margin of the eye. They are larger than R. clypeatus but smaller than western European species, such as R. banyulensis, R. lucifugus corsicus and R. grassei. For Cypriot soldiers, two size groups were identified, possibly in relation with the age of their mother colonies. Phylogenetic analysis shows that, contrary to what might be expected, the samples with the highest affinity with Cypriot samples are not those from the nearby mainland (south Turkey, Israel), but from north-eastern Greece. Comprehensive sampling in the nearby mainland is lacking, so the possibility that populations exist it that region with an affinity towards Cypriot Reticulitermes sp. cannot be ruled out. Together with samples from the Halkidiki peninsula, north-eastern Greece, northern Turkey and Crete, Cypriot Reticulitermes form a well-supported north-eastern Mediterranean clade.