Browsing by Subject "Lepidoptera"

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  • Linna, Susanna (Helsingin yliopisto, 2022)
    While there is no current consensus on what characterizes a heathy gut microbiome, there are evidence supporting the association of high microbial diversity with health stability in the host species. A growing literature suggests that microbial communities can withstand short-term anthropogenic changes with resilience, however enduring long-term changes might have a negative impact on the natural composition of host microbiome. Parasitism and anthropogenic disturbances resulting in habitat degradation might represent two of such long-term challenges to the invisible diversity of microbial communities, with consequences for the fitness of their host species. In this study, I tested whether parasitism by a specialist parasitoid and ecological changes due to anthropogenic habitat degradation affected the microbial community associated with the diapausing larvae of the Glanville Fritillary butterfly (Melitaea cinxia). The larval samples were collected in September 2012 from seven different communes across the Åland islands, from two extreme types of habitat patches (i.e., highly human-impacted habitats versus natural meadows). The parasitoid wasp Hyposoter horticola naturally parasitize approximately a third of the M. cinxia larvae in Åland, giving an opportunity to further investigate how parasitism might affect the larvae-associated bacterial community in this system. The DNA from the gut of each larva was extracted, and the bacterial V5-V6 region of the 16S gene was amplified and sequenced at the Finnish Institute for Molecular Medicine. The sequencing data was prepared for analysis by processing it through Mothur and QIIME2 data cleaning protocols. According to alpha- and beta-diversity metrics analyses, anthropogenic degradation of the habitat did not cause significant changes in the bacterial composition of the microbiota associated with diapausing larvae of M. cinxia, however, parasitism with the parasitoid wasp has a significant negative effect on the beta diversity of the microbial communities associated with the diapausing larvae.
  • Rosa, Elena; Woestmann, Luisa; Biere, Arjen; Saastamoinen, Marjo (2018)
    Host plant chemical composition critically shapes the performance of insect herbivores feeding on them. Some insects have become specialized on plant secondary metabolites, and even use them to their own advantage such as defense against predators. However, infection by plant pathogens can seriously alter the interaction between herbivores and their host plants. We tested whether the effects of the plant secondary metabolites, iridoid glycosides (IGs), on the performance and immune response of an insect herbivore are modulated by a plant pathogen. We used the IG-specialized Glanville fritillary butterfly Melitaea cinxia, its host plant Plantago lanceolata, and the naturally occurring plant pathogen, powdery mildew Podosphaera plantaginis, as model system. Pre-diapause larvae were fed on P. lanceolata host plants selected to contain either high or low IGs, in the presence or absence of powdery mildew. Larval performance was measured by growth rate, survival until diapause, and by investment in immunity. We assessed immunity after a bacterial challenge in terms of phenoloxidase (PO) activity and the expression of seven pre-selected insect immune genes (qPCR). We found that the beneficial effects of constitutive leaf IGs, that improved larval growth, were significantly reduced by mildew infection. Moreover, mildew presence downregulated one component of larval immune response (PO activity), suggesting a physiological cost of investment in immunity under suboptimal conditions. Yet, feeding on mildew-infected leaves caused an upregulation of two immune genes, lysozyme and prophenoloxidase. Our findings indicate that a plant pathogen can significantly modulate the effects of secondary metabolites on the growth of an insect herbivore. Furthermore, we show that a plant pathogen can induce contrasting effects on insect immune function. We suspect that the activation of the immune system toward a plant pathogen infection may be maladaptive, but the actual infectivity on the larvae should be tested.
  • Caterpillar Rearing Group (CRG), LepSoc Africa; Staude, Hermann; MacLean, Marion; Mecenero, Silvia; Pretorius, Rudolph J.; Oberprieler, Rolf G.; van Noort, Simon; Sharp, Allison; Sharp, Ian; Balona, Julio; Bradley, Suncana; Brink, Magriet; Morton, Andrew S.; Bodha, Magda J.; Collins, Steve C.; Grobler, Quartus; Edge, David A.; Williams, Mark C.; Sihvonen, Pasi (2020)
    We present an overview of the known host associations of larval Lepidoptera for southern Africa, based on a database of 11 628 rearings, including all Caterpillar Rearing Group (CRG) records and other published records. Rearings per Lepidoptera family show some bias in the rearing effort towards the more conspicuous families, ectophagous groups and non-detritus-feeders but in general follow species diversity. Recorded Lepidoptera host associations per host family for southern Africa are shown. Data analyses revealed the following general trends: of the 20 most reared species 13 are polyphagous; Fabaceae are the most utilised plant family with 2 122 associations, followed by Asteraceae (600), Malvaceae (564) and Anacardiaceae (476); 98.8 % of hosts are vascular plants; and of the 19 most utilised host species 18 are common trees or shrubs. We discuss possible reasons behind these trends, particularly the high utilisation of Fabaceae and the widespread use of trees and shrubs as hosts. We compare recorded host species numbers with species diversity for the 19 most recorded host families and discuss possible reasons for the low utilisation of four plant families with an exceptionally low percentage of Lepidoptera host species / plant host species diversity. All Lepidoptera families for which more than 100 rearings have been recorded (21 families) utilise one (or two in the case of Pyralidae, Nolidae and Hesperiidae) plant family exponentially more than any of the other families, with resulting histograms forming hyperbolic curves, as are typical of distributions of taxonomic assemblages in nature. We calculate an exponential factor to quantify this phenomenon and show that for all 21 Lepidoptera families one host family is utilised 6–33 times more than the average use of other host families. In this paper, the larvae and adults of 953 African, mostly South African, Lepidoptera species reared by the CRG between January 2016 and June 2019 are illustrated together with pertinent host information. 119 Lepidoptera-parasitoid associations are reported, comprising seven hymenopteran families and one dipteran family. With the current data release, larval host association records are now available for 2 826 Lepidoptera species in the southern African subregion, covering about 25 % of the described fauna.
  • Subedi, Bandana; Stewart, Alyssa B.; Neupane, Bijaya; Ghimire, Sudha; Adhikari, Hari (2021)
    Floral attributes often influence the foraging choices of nectar-feeding butterflies, given the close association between plants and these butterfly pollinators. The diversity of butterflies is known to a large extent in Nepal, but little information is available on the feeding habits of butterflies. This study was conducted along the periphery of Rupa Wetland from January to December 2019 to assess butterfly species diversity and to identify the factors influencing their foraging choices. In total, we recorded 1535 individuals of 138 species representing all six families. For our examination of butterfly-nectar plant interactions, we recorded a total of 298 individuals belonging to 31 species of butterfly visiting a total of 28 nectar plant species. Overall, total butterfly visitation was found to be significantly influenced by plant category (herbaceous preferred over woody), floral color (yellow white and purple preferred over pink), and corolla type (tubular preferred over nontubular). Moreover, there was a significant positive correlation between the proboscis length of butterflies and the corolla tube length of flowers. Examining each butterfly family separately revealed that, for four of the families (Lycaenidae, Nymphalidae, Papilionidae, and Pieridae), none of the tested factors (flower color, plant category, and corolla type) were shown to significantly influence butterfly abundance at flowers. However, Hesperidae abundance was found to be significantly influenced by both flower color (with more butterflies observed at yellow flowers than purple) and flower type (with more butterflies observed at tubular flowers than nontubular flowers). Our results reveal that Rupa Lake is a suitable habitat for butterflies, providing valuable floral resources. Hence, further detailed studies encompassing all seasons, a greater variety of plants, and other influential factors in different ecological regions are fundamental for creating favorable environments to sustain important butterfly pollinators and help create balanced wetland ecosystems.
  • Byers, Kelsey J. R. P.; Darragh, Kathy; Fernanda Garza, Sylvia; Abondano Almeida, Diana; Warren, Ian A.; Rastas, Pasi M. A.; Merrill, Richard M.; Schulz, Stefan; McMillan, W. Owen; Jiggins, Chris D. (2021)
    The degree to which loci promoting reproductive isolation cluster in the genome-that is, the genetic architecture of reproductive isolation-can influence the tempo and mode of speciation. Tight linkage between these loci can facilitate speciation in the face of gene flow. Pheromones play a role in reproductive isolation in many Lepidoptera species, and the role of endogenously produced compounds as secondary metabolites decreases the likelihood of pleiotropy associated with many barrier loci. Heliconius butterflies use male sex pheromones to both court females (aphrodisiac wing pheromones) and ward off male courtship (male-transferred antiaphrodisiac genital pheromones), and it is likely that these compounds play a role in reproductive isolation between Heliconius species. Using a set of backcross hybrids between H. melpomene and H. cydno, we investigated the genetic architecture of putative male pheromone compound production. We found a set of 40 significant quantitative trait loci (QTL) representing 33 potential pheromone compounds. QTL clustered significantly on two chromosomes, chromosome 8 for genital compounds and chromosome 20 for wing compounds, and chromosome 20 was enriched for potential pheromone biosynthesis genes. There was minimal overlap between pheromone QTL and known QTL for mate choice and color pattern. Nonetheless, we did detect linkage between a QTL for wing androconial area and optix, a color pattern locus known to play a role in reproductive isolation in these species. This tight clustering of putative pheromone loci might contribute to coincident reproductive isolating barriers, facilitating speciation despite ongoing gene flow.
  • Hällfors, Maria H.; Pöyry, Juha; Heliölä, Janne; Kohonen, Ilmari; Kuussaari, Mikko; Leinonen, Reima; Schmucki, Reto; Sihvonen, Pasi; Saastamoinen, Marjo (Blackwell Science, 2021)
    Ecology Letters 24: 1619-1632
    Species can adapt to climate change by adjusting in situ or by dispersing to new areas, and these strategies may complement or enhance each other. Here, we investigate temporal shifts in phenology and spatial shifts in northern range boundaries for 289 Lepidoptera species by using long-term data sampled over two decades. While 40% of the species neither advanced phenology nor moved northward, nearly half (45%) used one of the two strategies. The strongest positive population trends were observed for the minority of species (15%) that both advanced flight phenology and shifted their northern range boundaries northward. We show that, for boreal Lepidoptera, a combination of phenology and range shifts is the most viable strategy under a changing climate. Effectively, this may divide species into winners and losers based on their propensity to capitalize on this combination, with potentially large consequences on future community composition.
  • Wirta, Helena K.; Hebert, Paul D. N.; Kaartinen, Riikka; Prosser, Sean W.; Varkonyi, Gergely; Roslin, Tomas (2014)
  • Heikkila, Maria; Mutanen, Marko; Wahlberg, Niklas; Sihvonen, Pasi; Kaila, Lauri (2015)
    Background: Ditrysia comprise close to 99 % of all butterflies and moths. The evolutionary relationships among the ditrysian superfamilies have received considerable attention in phylogenetic studies based on DNA and transcriptomic data, but the deepest divergences remain for large parts unresolved or contradictory. To obtain complementary insight into the evolutionary history of the clade, and to test previous hypotheses on the subdivision of Ditrysia based on morphology, we examine the morphology of larvae, pupae and adult males and females of 318 taxa representing nearly all ditrysian superfamilies and families. We present the most comprehensive morphological dataset on Ditrysia to date, consisting of over 500 morphological characters. The data are analyzed alone and combined with sequence data (one mitochondrial and seven nuclear protein-coding gene regions, sequenced from 422 taxa). The full dataset consists of 473 exemplar species. Analyses are performed using maximum likelihood methods, and parsimony methods for the morphological dataset. We explore whether combining morphological data and DNA-data can stabilize taxa that are unstable in phylogenetic studies based on genetic data only. Results: Morphological characters are found phylogenetically informative in resolving apical nodes (superfamilies and families), but characters serving as evidence of relatedness of larger assemblages are few. Results include the recovery of a monophyletic Tineoidea, Sesioidea and Cossoidea, and a stable position for some unstable taxa (e.g. Epipyropidae, Cyclotornidae, Urodoidea + Schreckensteinioidea). Several such taxa, however, remain unstable even though morphological characters indicate a position in the tree (e.g. Immidae). Evidence supporting affinities between clades are suggested, e.g. a novel larval synapomorphy for Tineidae. We also propose the synonymy of Tineodidae with Alucitidae, syn. nov. Conclusions: The large morphological dataset provides information on the diversity and distribution of morphological traits in Ditrysia, and can be used in future research on the evolution of these traits, in identification keys and in identification of fossil Lepidoptera. The "backbone" of the phylogeny for Ditrysia remains largely unresolved. As previously proposed as an explanation for the scarcity of molecular signal in resolving the deeper nodes, this may be due to the rapid radiation of Ditrysia in the Cretaceous.
  • de Jong, M. A.; Saastamoinen, Marjo (2018)
    Thermal tolerance has a major effect on individual fitness and species distributions and can be determined by genetic variation and phenotypic plasticity. We investigate the effects of developmental and adult thermal conditions on cold tolerance, measured as chill coma recovery (CCR) time, during the early and late adult stage in the Glanville fritillary butterfly. We also investigate the genetic basis of cold tolerance by associating CCR variation with polymorphisms in candidate genes that have a known role in insect physiology. Our results demonstrate that a cooler developmental temperature leads to reduced cold tolerance in the early adult stage, whereas cooler conditions during the adult stage lead to increased cold tolerance. This suggests that adult acclimation, but not developmental plasticity, of adult cold tolerance is adaptive. This could be explained by the ecological conditions the Glanville fritillary experiences in the field, where temperature during early summer, but not spring, is predictive of thermal conditions during the butterfly's flight season. In addition, an amino acid polymorphism (Ala-Glu) in the gene flightin, which has a known function in insect flight and locomotion, was associated with CCR. These amino acids have distinct biochemical properties and may thus affect protein function and/or structure. To our knowledge, our study is the first to link genetic variation in flightin to cold tolerance, or thermal adaptation in general.
  • Rytkönen, Seppo; Vesterinen, Eero J.; Westerduin, Coen; Leviäkangas, Tiina; Vatka, Emma; Mutanen, Marko; Välimäki, Panu; Hukkanen, Markku; Suokas, Marko; Orell, Markku (2019)
    Diets play a key role in understanding trophic interactions. Knowing the actual structure of food webs contributes greatly to our understanding of biodiversity and ecosystem functioning. The research of prey preferences of different predators requires knowledge not only of the prey consumed, but also of what is available. In this study, we applied DNA metabarcoding to analyze the diet of 4 bird species (willow tits Poecile montanus, Siberian tits Poecile cinctus, great tits Parus major and blue tits Cyanistes caeruleus) by using the feces of nestlings. The availability of their assumed prey (Lepidoptera) was determined from feces of larvae (frass) collected from the main foraging habitat, birch (Betula spp.) canopy. We identified 53 prey species from the nestling feces, of which 11 (21%) were also detected from the frass samples (eight lepidopterans). Approximately 80% of identified prey species in the nestling feces represented lepidopterans, which is in line with the earlier studies on the parids' diet. A subsequent laboratory experiment showed a threshold for fecal sample size and the barcoding success, suggesting that the smallest frass samples do not contain enough larval DNA to be detected by high-throughput sequencing. To summarize, we apply metabarcoding for the first time in a combined approach to identify available prey (through frass) and consumed prey (via nestling feces), expanding the scope and precision for future dietary studies on insectivorous birds.
  • Girardello, Marco; Chapman, Anna; Dennis, Roger; Kaila, Lauri; Borges, Paulo; Santangeli, Andrea (2019)
    Species distribution data are crucial for assessing the conservation status of species (red listing, IUCN) and implementing international conservation targets, such as those set by the International Convention on Biological Diversity. Although there have been a number of efforts aimed at aggregating biodiversity data, information on the distribution of many taxa is still scanty (i.e. the Wallacean Shortfall). In this study, we use a large database, including over 19 million species occurrence records, to identify knowledge gaps in biodiversity inventories for butterfly records at a global level. Bayesian hierarchical spatial models were used to quantify the relationship between gaps in inventory completeness and the density of roads, protected areas and elevational range, the former variable being a proxy for accessibility, the latter two for attractiveness to recorders. Our results show that despite > 100 years of butterfly sampling, knowledge of the distribution of butterflies is still limited in tropical areas. The results revealed that gaps in butterfly inventories are largely concentrated in areas of low elevational range, low density of protected areas and low road density. We conclude that the Wallacean Shortfall is a problem even for one of the best studied insect groups. In the light of these data limitations, we discuss prospects for filling gaps in butterfly inventories at the global scale within relatively short time frames. We argue that a combination of citizen science and quantitative tools may help to fill knowledge gaps and inform conservation decisions.
  • Fourcade, Yoan; WallisDeVries, Michiel F.; Kuussaari, Mikko; Swaay, Chris A. M.; Heliölä, Janne; Öckinger, Erik (John Wiley & Sons Ltd, 2021)
    Ecology Letters 24: 5, 950-957
    Habitat fragmentation may present a major impediment to species range shifts caused by climate change, but how it affects local community dynamics in a changing climate has so far not been adequately investigated empirically. Using long-term monitoring data of butterfly assemblages, we tested the effects of the amount and distribution of semi-natural habitat (SNH), moderated by species traits, on climate-driven species turnover. We found that spatially dispersed SNH favoured the colonisation of warm-adapted and mobile species. In contrast, extinction risk of cold-adapted species increased in dispersed (as opposed to aggregated) habitats and when the amount of SNH was low. Strengthening habitat networks by maintaining or creating stepping-stone patches could thus allow warm-adapted species to expand their range, while increasing the area of natural habitat and its spatial cohesion may be important to aid the local persistence of species threatened by a warming climate.
  • Lee, Kyung Min; Kivelä, Sami M.; Ivanov, Vladislav; Hausmann, Axel; Kaila, Lauri; Wahlberg, Niklas; Mutanen, Marko (2018)
    A rapid shift from traditional Sanger sequencing-based molecular methods to the phylogenomic approach with large numbers of loci is underway. Among phylogenomic methods, restriction site associated DNA (RAD) sequencing approaches have gained much attention as they enable rapid generation of up to thousands of loci randomly scattered across the genome and are suitable for nonmodel species. RAD data sets however suffer from large amounts of missing data and rapid locus dropout along with decreasing relatedness among taxa. The relationship between locus dropout and the amount of phylogenetic information retained in the data has remained largely uninvestigated. Similarly, phylogenetic hypotheses based on RAD have rarely been compared with phylogenetic hypotheses based on multilocus Sanger sequencing, even less so using exactly the same species and specimens. We compared the Sanger-based phylogenetic hypothesis (8 loci; 6172 bp) of 32 species of the diverse moth genus Eupithecia (Lepidoptera, Geometridae) to that based on double-digest RAD sequencing (3256 loci; 726,658 bp). We observed that topologies were largely congruent, with some notable exceptions that we discuss. The locus dropout effect was strong. We demonstrate that number of loci is not a precise measure of phylogenetic information since the number of single-nucleotide polymorphisms (SNPs) may remain low at very shallow phylogenetic levels despite large numbers of loci. As we hypothesize, the number of SNPs and parsimony informative SNPs (PIS) is low at shallow phylogenetic levels, peaks at intermediate levels and, thereafter, declines again at the deepest levels as a result of decay of available loci. Similarly, we demonstrate with empirical data that the locus dropout affects the type of loci retained, the loci found in many species tending to show lower interspecific distances than those shared among fewer species. We also examine the effects of the numbers of loci, SNPs, and PIS on nodal bootstrap support, but could not demonstrate with our data our expectation of a positive correlation between them. We conclude that RAD methods provide a powerful tool for phylogenomics at an intermediate phylogenetic level as indicated by its broad congruence with an eight-gene Sanger data set in a genus of moths. When assessing the quality of the data for phylogenetic inference, the focus should be on the distribution and number of SNPs and PIS rather than on loci.
  • Melero, Yolanda; Evans, Luke C.; Kuussaari, Mikko; Schmucki, Reto; Stefanescu, Constantí; Roy, David B.; Oliver, Tom H. (Springer Science and Business Media LLC, 2022)
    Communications Biology
    Climatic anomalies are increasing in intensity and frequency due to rapid rates of global change, leading to increased extinction risk for many species. The impacts of anomalies are likely to vary between species due to different degrees of sensitivity and extents of local adaptation. Here, we used long-term butterfly monitoring data of 143 species across six European bioclimatic regions to show how species’ population dynamics have responded to local or globally-calculated climatic anomalies, and how species attributes mediate these responses. Contrary to expectations, degree of apparent local adaptation, estimated from the relative population sensitivity to local versus global anomalies, showed no associations with species mobility or reproductive rate but did contain a strong phylogenetic signal. The existence of phylogenetically-patterned local adaptation to climate has important implications for forecasting species responses to current and future climatic conditions and for developing appropriate conservation practices.
  • Murillo Ramos, Leidys Del Carmen; Chazot, Nicolas; Sihvonen, Pasi; Õunap, Erki; Jiang, Nan; Han, Hongxiang; Clarke, John T.; Davis, Robert B.; Tammaru, Toomas; Wahlberg, Niklas (2021)
    Understanding how and why some groups have become more species-rich than others, and how past biogeography may have shaped their current distribution, are questions that evolutionary biologists have long attempted to answer. We investigated diversification patterns and historical biogeography of a hyperdiverse lineage of Lepidoptera, the geometrid moths, by studying its most species-rich tribe Boarmiini, which comprises ca. 200 genera and ca. known 3000 species. We inferred the evolutionary relationships of Boarmiini based on a dataset of 346 taxa, with up to eight genetic markers under a maximum likelihood approach. The monophyly of Boarmiiniis strongly supported. However, the phylogenetic position of many taxa does not agree with current taxonomy, although the monophyly of most major genera within the tribe is supported after minor adjustments. Three genera are synonymized, one new combination is proposed, and four species are placed in incertae sedis within Boarmiini. Our results support the idea of a rapid initial diversification of Boarmiini, which also implies that no major taxonomic subdivisions of the group can currently be proposed. A time-calibrated tree and biogeographical analyses suggest that boarmiines appeared in Laurasia ca. 52 Mya, followed by dispersal events throughout the Australasian, African and Neotropical regions. Most of the transcontinental dispersal events occurred in the Eocene, a period of intense geological activity and rapid climate change. Diversification analyses showed a relatively constant diversification rate for all Boarmiini, except in one clade containing the species-rich genus Cleora. The present work represents a substantial contribution towards understanding the evolutionary origin of Boarmiini moths. Our results, inevitably biased by taxon sampling, highlight the difficulties with working on species-rich groups that have not received much attention outside of Europe. Specifically, poor knowledge of the natural history of geometrids (particularly in tropical clades) limits our ability to identify key innovations underlying the diversification of boarmiines.
  • Gauthier, Jérémy; Pajkovic, Mila; Neuenschwander, Samuel; Kaila, Lauri; Schmid, Sarah; Orlando, Ludovic; Alvarez, Nadir (2020)
    Erosion of biodiversity generated by anthropogenic activities has been studied for decades in many areas at species level, using taxa monitoring. In contrast, genetic erosion within species has rarely been tracked, and is often studied by inferring past population dynamics from contemporaneous estimators. An alternative to such inferences is the direct examination of past genes, by analysing museum collection specimens. While providing direct access to genetic variation over time, historical DNA is usually not optimally preserved, and it is necessary to apply genotyping methods based on hybridization-capture to unravel past genetic variation. In this study, we apply such a method (i.e., HyRAD), to large time series of two butterfly species in Finland, and present a new bioinformatic pipeline, namely PopHyRAD, that standardizes and optimizes the analysis of HyRAD data at the within-species level. In the localities for which the data retrieved have sufficient power to accurately examine genetic dynamics through time, we show that genetic erosion has increased across the last 100 years, as revealed by signatures of allele extinctions and heterozygosity decreases, despite local variations. In one of the two butterflies (Erebia embla), isolation by distance also increased through time, revealing the effect of greater habitat fragmentation over time.
  • Kohonen, Ilmari (Helsingin yliopisto, 2020)
    Global biodiversity continues to decline. Recent reports of decline in insect abundance and biomass are concerning, given the crucial roles insects play in multiple ecosystem processes, such as pollination, nutrient cycling and as a food resource for higher trophic levels. Based on the current state of the literature, it appears that total insect abundance and biomass are in decline, but there is considerable variation in trajectories in different regions and taxa. Many studies report on either aggregated community abundance or biomass, but few have examined how closely these two variables are correlated. For example, declining trends in large-bodied species could have disproportionately large effects on total biomass, even if total abundance remained stable. This, in turn, could have substantial consequences for predators dependent on insect biomass for food. Whether studying total abundance or biomass, long-term monitoring data are essential for robust estimation of temporal trends. In my thesis, I investigated trends in macro-moth abundance and biomass using data from the Finnish moth monitoring scheme (Nocturna) over a period of 24 years (1993-2016). My main objectives were to explore whether total abundance and biomass have changed over the timeframe examined, and to estimate the degree of correlation between the two variables in these data. As is typical for monitoring programs, only counts of moth individuals have been recorded. In order to obtain information on biomass, I created a predictive model for converting the recorded abundance counts to dry biomass based on species mean wingspan and body robustness. I weighed museum collection specimens of common moth species of variable sizes, and used these data for fitting the model. Additionally, I also investigated how local weather (thermal and precipitation) conditions during the growing season and winter relate to interannual variation in total abundance. Finally, I analysed potentially informative species traits (e.g., wingspan, voltinism, overwintering stage) in relation to population trends of individual species, because such associations could be underlying change in total abundance or biomass. There was no long-term change in total macro-moth abundance or biomass over the 24-year monitoring period. Abundance and biomass were very highly correlated (r > 0.9). In terms of interannual variation, total moth abundance and biomass showed a distinctive pattern suggestive of periodicity, with peaks at approximately 10-year intervals. Local weather conditions were very weakly associated with annual change rates of total abundance, leaving the interannual pattern unexplained. Lichen-feeding and multivoltinism (multiple generations per year) were positively related to population trends, supporting earlier findings. Especially relevant to potential trends in biomass, wingspan showed no relationship with positive or negative trends, which is in line with the high correlation between abundance and biomass in this dataset. My results imply that the total abundance and biomass trends in boreal Europe diverge from those commonly reported from temperate Europe. Further research is required to shed light on factors underlying total insect abundance and biomass trends. The method I developed for converting moth abundance to biomass is applicable to similar work elsewhere.
  • Twort, Victoria Gwendoline; Blande, Daniel; Duplouy, Anne (2022)
    Background Maternally inherited bacterial symbionts are extremely widespread in insects. They owe their success to their ability to promote their own transmission through various manipulations of their hosts’ life-histories. Many symbionts however very often go undetected. Consequently, we have only a restricted idea of the true symbiont diversity in insects, which may hinder our understanding of even bigger questions in the field such as the evolution or establishment of symbiosis. Results In this study, we screened publicly available Lepidoptera genomic material for two of the most common insect endosymbionts, namely Wolbachia and Spiroplasma, in 1904 entries, encompassing 106 distinct species. We compared the performance of two screening software, Kraken2 and MetaPhlAn2, to identify the bacterial infections and using a baiting approach we reconstruct endosymbiont genome assemblies. Of the 106 species screened, 20 (19%) and nine (8.5%) were found to be infected with either Wolbachia or Spiroplasma, respectively. Construction of partial symbiotic genomes and phylogenetic analyses suggested the Wolbachia strains from the supergroup B were the most prevalent type of symbionts, while Spiroplasma infections were scarce in the Lepidoptera species screened here. Conclusions Our results indicate that many of the host-symbiont associations remain largely unexplored, with the majority of associations we identify never being recorded before. This highlights the usefulness of public databases to explore the hidden diversity of symbiotic entities, allowing the development of hypotheses regarding host-symbiont associations. The ever-expanding genomic databases provide a diverse databank from which one can characterize and explore the true diversity of symbiotic entities.
  • Heliövaara, Kari; Väisänen, Rauno (Suomen metsätieteellinen seura, 1986)