Adaptive evolution of invasive fall armyworms to maize with potential involvement of Cytochrome P450 genes.

Background: An invasion occurs when introduced species establish and maintain stable populations in areas outside of their native habitat. Adaptive evolution has been proposed to contribute to this process. The fall armyworm (Spodoptera frugiperda) is one of the major pest insects infesting maize in both invaded and native areas.

Complex multiple introductions drive fall armyworm invasions into Asia and Australia.

The fall armyworm (FAW) Spodoptera frugiperda is thought to have undergone a rapid 'west-to-east' spread since 2016 when it was first identified in western Africa. Between 2018 and 2020, it was recorded from South Asia (SA), Southeast Asia (SEA), East Asia (EA), and Pacific/Australia (PA). Population genomic analyses enabled the understanding of pathways, population sources, and gene flow in this notorious agricultural pest species.

The evolutionary process of invasion in the fall armyworm (Spodoptera frugiperda).

The fall armyworm (FAW; Spodoptera frugiperda) is one of the major agricultural pest insects. FAW is native to the Americas, and its invasion was first reported in West Africa in 2016. Then it quickly spread through Africa, Asia, and Oceania, becoming one of the main threats to corn production.

Host-plant adaptation as a driver of incipient speciation in the fall armyworm (Spodoptera frugiperda).

Background: Divergent selection on host-plants is one of the main evolutionary forces driving ecological speciation in phytophagous insects. The ecological speciation might be challenging in the presence of gene flow and assortative mating because the direction of divergence is not necessarily the same between ecological selection (through host-plant adaptation) and assortative mating. The fall armyworm (FAW), a major lepidopteran pest species, is composed of two sympatric strains, corn and rice strains, named after two of their preferred host-plants.

Global population genomic signature of Spodoptera frugiperda (fall armyworm) supports complex introduction events across the Old World.

Native to the Americas, the invasive Spodoptera frugiperda (fall armyworm; FAW) was reported in West Africa in 2016, followed by its chronological detection across the Old World and the hypothesis of an eastward Asia expansion. We explored population genomic signatures of American and Old World FAW and identified 12 maternal mitochondrial DNA genome lineages across the invasive range. 870 high-quality nuclear single nucleotide polymorphic DNA markers identified five distinct New World population clusters, broadly reflecting FAW native geographical ranges and the absence of host-plant preferences.

H3K9me2 genome-wide distribution in the holocentric insect Spodoptera frugiperda (Lepidoptera: Noctuidae).

Background: Eukaryotic genomes are packaged by Histone proteins in a structure called chromatin. There are different chromatin types. Euchromatin is typically associated with decondensed, transcriptionally active regions and heterochromatin to more condensed regions of the chromosomes.

Integrated miRNA and transcriptome profiling to explore the molecular determinism of convergent adaptation to corn in two lepidopteran pests of agriculture.

Background: The degree to which adaptation to same environment is determined by similar molecular mechanisms, is a topic of broad interest in evolutionary biology, as an indicator of evolutionary predictability. We wished to address if adaptation to the same host plant in phytophagous insects involved related gene expression patterns. We compared sRNA-Seq and RNA-Seq data between two pairs of taxa of Ostrinia and Spodoptera frugiperda sharing maize as host-plant.

Geographic Monitoring of Insecticide Resistance Mutations in Native and Invasive Populations of the Fall Armyworm.

Field evolved resistance to insecticides is one of the main challenges in pest control. The fall armyworm (FAW) is a lepidopteran pest species causing severe crop losses, especially corn. While native to the Americas, the presence of FAW was confirmed in West Africa in 2016.

A novel reference dated phylogeny for the genus Spodoptera Guenée (Lepidoptera: Noctuidae: Noctuinae): new insights into the evolution of a pest-rich genus.

The noctuid genus Spodoptera currently consists of 31 species with varied host plant breadths, ranging from monophagous and oligophagous non-pest species to polyphagous pests of economic importance. Several of these pest species have become major invaders, colonizing multiple continents outside their native range. Such is the case of the infamous fall armyworm, Spodoptera frugiperda (J.

Positive selection alone is sufficient for whole genome differentiation at the early stage of speciation process in the fall armyworm.

Background: The process of speciation involves differentiation of whole genome sequences between a pair of diverging taxa. In the absence of a geographic barrier and in the presence of gene flow, genomic differentiation may occur when the homogenizing effect of recombination is overcome across the whole genome. The fall armyworm is observed as two sympatric strains with different host-plant preferences across the entire habitat.

Adaptation by copy number variation increases insecticide resistance in the fall armyworm.

Understanding the genetic basis of insecticide resistance is a key topic in agricultural ecology. The adaptive evolution of multi-copy detoxification genes has been interpreted as a cause of insecticide resistance, yet the same pattern can also be generated by the adaptation to host-plant defense toxins. In this study, we tested in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), if adaptation by copy number variation caused insecticide resistance in two geographically distinct populations with different levels of resistance and the two host-plant strains.

Genetic structure and insecticide resistance characteristics of fall armyworm populations invading China.

The rapid wide-scale spread of fall armyworm (Spodoptera frugiperda) has caused serious crop losses globally. However, differences in the genetic background of subpopulations and the mechanisms of rapid adaptation behind the invasion are still not well understood. Here we report the assembly of a 390.

Characterization and expression profiling of microRNAs in response to plant feeding in two host-plant strains of the lepidopteran pest Spodoptera frugiperda.

Background: A change in the environment may impair development or survival of living organisms leading them to adapt to the change. The resulting adaptation trait may reverse, or become fixed in the population leading to evolution of species. Deciphering the molecular basis of adaptive traits can thus give evolutionary clues.

Linear 1 sequences drive random integration of a reporter gene in transfected cells.

Background: The 1 isolated from (hereafter JcDV) is an invertebrate parvovirus considered as a viral transduction vector as well as a potential tool for the biological control of insect pests. Previous works showed that JcDV-based circular plasmids experimentally integrate into insect cells genomic DNA.

Methods: In order to approach the natural conditions of infection and possible integration, we generated linear JcDV- based molecules which were transfected into non permissive () cultured cells.

Genomic adaptation to polyphagy and insecticides in a major East Asian noctuid pest.

The tobacco cutworm, Spodoptera litura, is among the most widespread and destructive agricultural pests, feeding on over 100 crops throughout tropical and subtropical Asia. By genome sequencing, physical mapping and transcriptome analysis, we found that the gene families encoding receptors for bitter or toxic substances and detoxification enzymes, such as cytochrome P450, carboxylesterase and glutathione-S-transferase, were massively expanded in this polyphagous species, enabling its extraordinary ability to detect and detoxify many plant secondary compounds. Larval exposure to insecticidal toxins induced expression of detoxification genes, and knockdown of representative genes using short interfering RNA (siRNA) reduced larval survival, consistent with their contribution to the insect's natural pesticide tolerance.

Two genomes of highly polyphagous lepidopteran pests (Spodoptera frugiperda, Noctuidae) with different host-plant ranges.

Emergence of polyphagous herbivorous insects entails significant adaptation to recognize, detoxify and digest a variety of host-plants. Despite of its biological and practical importance - since insects eat 20% of crops - no exhaustive analysis of gene repertoires required for adaptations in generalist insect herbivores has previously been performed. The noctuid moth Spodoptera frugiperda ranks as one of the world's worst agricultural pests.

Phylogenetic molecular species delimitations unravel potential new species in the pest genus Spodoptera Guenée, 1852 (Lepidoptera, Noctuidae).

Nowadays molecular species delimitation methods promote the identification of species boundaries within complex taxonomic groups by adopting innovative species concepts and theories (e.g. branching patterns, coalescence).

Genomics of adaptation to host-plants in herbivorous insects.

Herbivorous insects represent the most species-rich lineages of metazoans. The high rate of diversification in herbivorous insects is thought to result from their specialization to distinct host-plants, which creates conditions favorable for the build-up of reproductive isolation and speciation. These conditions rely on constraints against the optimal use of a wide range of plant species, as each must constitute a viable food resource, oviposition site and mating site for an insect.

Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains.

Evolutionary history of x-tox genes in three lepidopteran species: origin, evolution of primary and secondary structure and alternative splicing, generating a repertoire of immune-related proteins.

The proteins of the X-tox family have imperfectly conserved tandem repeats of several defensin-like motifs known as cysteine-stabilized αβ (CS-αβ) motifs. These immune-related proteins are inducible and expressed principally in hemocytes, but they have lost the antimicrobial properties of the ancestral defensins from which they evolved. We compared x-tox gene structure and expression in three lepidopteran species (Spodoptera frugiperda, Helicoverpa armigera and Bombyx mori).

Correlation of LNCR rasiRNAs expression with heterochromatin formation during development of the holocentric insect Spodoptera frugiperda.

Repeat-associated small interfering RNAs (rasiRNAs) are derived from various genomic repetitive elements and ensure genomic stability by silencing endogenous transposable elements. Here we describe a novel subset of 46 rasiRNAs named LNCR rasiRNAs due to their homology with one long non-coding RNA (LNCR) of Spodoptera frugiperda. LNCR operates as the intermediate of an unclassified transposable element (TE-LNCR).

Characterization of a CENP-B homolog in the holocentric Lepidoptera Spodoptera frugiperda.

The discovery of an homolog of the human centromeric protein B, CENP-B, in an EST database of the holocentric insect species Spodoptera frugiperda prompted us to further characterize that gene because i) CENP-B has not been described in invertebrates yet ii) it should be a milestone in the molecular characterization of the holocentric centromere of Lepidoptera. Like its human counterpart, the Sf CENP-B protein is related to the transposase of the pogo transposable element (TE) of D. melanogaster.

Membrane docking of an aggregation-prone protein improves its solubilization.

We used preS2-S'-beta-galactosidase, a three domain fusion protein that aggregates extensively at 43 degrees C in the cytoplasm of Escherichia coli to search for multicopy suppressors of protein aggregation and inclusion bodies formation, and took advantage of the known differential solubility of preS2-S'-beta-galactosidase at 37 and 43 degrees C to develop a selection procedure for the gene products that would prevent its aggregation in vivo at 43 degrees C. First, we demonstrate that the differential solubility of preS2-S'-beta-galactosidase results in a lactose-positive phenotype at 37 degrees C as opposed to a lactose-negative phenotype at 43 degrees C. We searched for multicopy suppressors of preS2-S'-beta-galactosidase aggregation at 43 degrees C by selecting pink lactose-positive colonies on a background of white lactose-negative colonies after transformation of bacteria with an E.