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Patterns of colonization and diversification on islands provide valuable insights into evolutionary processes. Due to their unique geographic position and well known history, the Galapagos Islands are an important model system for evolutionary studies. Here we investigate the evolutionary history of a winged grasshopper genus to infer its origin and pattern of colonization in the Galapagos archipelago. The grasshopper genus Sphingonotus has radiated extensively in the Palaearctic and many species are endemic to islands. In the New World, the genus is largely replaced by the genus Trimerotropis. Oddly, in the Caribbean and on the Galapagos archipelago, two species of Sphingonotus are found, which has led to the suggestion that these might be the result of anthropogenic translocations from Europe. Here, we test this hypothesis using mitochondrial and nuclear DNA sequences from a broad sample of Sphingonotini and Trimerotropini species from the Old World and New World. The genetic data show two distinct genetic clusters representing the New World Trimerotropini and the Old World Sphingonotini. However, the Sphingonotus species from Galapagos and the Caribbean split basally within the Old World Sphingonotini lineage. The Galapagos and Caribbean species appear to be related to Old World taxa, but are not the result of recent anthropogenic translocations as revealed by divergence time estimates. Distinct genetic lineages occur on the four investigated Galapagos Islands, with deep splits among them compared to their relatives from the Palaearctic. A scenario of a past wider distribution of Sphingonotus in the New World with subsequent extinction on the mainland and replacement by Trimerotropis might explain the disjunct distribution.

Two new species of the genus and the first report of a male Zheng, 1990 are presented. The new species has similar morphological features to Uvarov, 1933, but it differs from the latter in having 1) the hind tibia black; 2) the epiproct, in males, with a median groove in the basal 1/2 and in the apical 1/4; 3) the denticles of the male epiproct black; 4) the outside of the hind femur reddish-brown on the basal 1/4 and black on the apical 3/4; and 5) the ventral face of the hind femur black on the outer side. The second new species, , is morphologically close to Zheng, 1980 but differs from the latter in having 1) the length of the middle segment (12th segment) of antennae 1.2 times longer than its width; 2) the subgenital plate sharp-cornered in males; 3) the ovipositor smooth; 4) the upper half of hind femur outside surface with two black spots; and 5) the ventral face of the hind femur black on its outer side, red on the basal 2/3, and black on the apical 1/3 of its inner side. Finally, we provide a key to all known species of .

Evidence for global insect declines mounts, increasing our need to understand underlying mechanisms. We test the nutrient dilution (ND) hypothesis—the decreasing concentration of essential dietary minerals with increasing plant productivity—that particularly targets insect herbivores. Nutrient dilution can result from increased plant biomass due to climate or CO₂ enrichment. Additionally, when considering long-term trends driven by climate, one must account for large-scale oscillations including El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). We combine long-term datasets of grasshopper abundance, climate, plant biomass, and end-of-season foliar elemental content to examine potential drivers of abundance cycles and trends of this dominant herbivore. Annual grasshopper abundances in 16- and 22-y time series from a Kansas prairie revealed both 5-y cycles and declines of 2.1–2.7%/y. Climate cycle indices of spring ENSO, summer NAO, and winter or spring PDO accounted for 40–54% of the variation in grasshopper abundance, mediated by effects of weather and host plants. Consistent with ND, grass biomass doubled and foliar concentrations of N, P, K, and Na—nutrients which limit grasshopper abundance—declined over the same period. The decline in plant nutrients accounted for 25% of the variation in grasshopper abundance over two decades. Thus a warming, wetter, more CO₂-enriched world will likely contribute to declines in insect herbivores by depleting nutrients from their already nutrient-poor diet. Unlike other potential drivers of insect declines—habitat loss, light and chemical pollution—ND may be widespread in remaining natural areas.

Animal genomes vary widely in size, and much of their architecture and content remains poorly understood. Even among related groups, such as orders of insects, genomes may vary in size by orders of magnitude–for reasons unknown. The largest known insect genomes were repeatedly found in Orthoptera, e.g., Podisma pedestris (1C = 16.93 pg), Stethophyma grossum (1C = 18.48 pg) and Bryodemella holdereri (1C = 18.64 pg). While all these species belong to the suborder of Caelifera, the ensiferan Deracantha onos (1C = 19.60 pg) was recently found to have the largest genome. Here, we present new genome size estimates of 50 further species of Ensifera (superfamilies Gryllidea, Tettigoniidea) and Caelifera (Acrididae, Tetrigidae) based on flow cytometric measurements. We found that Bryodemella tuberculata (Caelifera: Acrididae) has the so far largest measured genome of all insects with 1C = 21.96 pg (21.48 gBp). Species of Orthoptera with 2n = 16 and 2n = 22 chromosomes have significantly larger genomes than species with other chromosome counts. Gryllidea genomes vary between 1C = 0.95 and 2.88 pg, and Tetrigidae between 1C = 2.18 and 2.41, while the genomes of all other studied Orthoptera range in size from 1C = 1.37 to 21.96 pg. Reconstructing ancestral genome sizes based on a phylogenetic tree of mitochondrial genomic data, we found genome size values of >15.84 pg only for the nodes of Bryodemella holdereri / B . tuberculata and Chrysochraon dispar / Euthystira brachyptera . The predicted values of ancestral genome sizes are 6.19 pg for Orthoptera, 5.37 pg for Ensifera, and 7.28 pg for Caelifera. The reasons for the large genomes in Orthoptera remain largely unknown, but a duplication or polyploidization seems unlikely as chromosome numbers do not differ much. Sequence-based genomic studies may shed light on the underlying evolutionary mechanisms.

The general distribution of the grasshopper Eremippus simplex (Eversmann, 1859) is described. Its taxonomic position and ecological peculiarities are characterized. It is one of the most widespread representatives of the genus and is the only species crossing the 52nd parallel in the north direction. The species is associated with dry steppes, semi-deserts and northern deserts and prefers habitats with dominance of different low sagebrushes (Artemisia spp.) and salinized soils. In the southern parts of Siberia and in the south-eastern parts of European Russia, its populations were and are very rare and insular. The MaxEnt models generated for the contemporary period and for 2021–2040 and 2041–2060 according the Shared Socioeconomic Pathway 3-7.0 and the global climate model CNRM- ESM2-1 provide an opportunity to evaluate the suitability of conditions for the species and show that, in the future, the general character of its distribution may change quite slightly, but its populations may become more prosperous in the future.

Eukaryotic genomes are often rich in DNA repetitive elements, involving both transposable elements (TE) and tandemly repeated satellite DNA. Grasshopper species, known for their large genome sizes, comprising relatively a high proportion of genomic repeats. This study aimed to identify and perform a comparative analysis of DNA repetitive content in eight grasshopper species from the Pyrgomorphidae and Acrididae families. We utilized unassembled low-coverage Illumina paired-end short reads in the RepeatExplorer2 pipeline to identify genomic repeats, and RepeatMasker to estimate their abundance and divergence activity. Flow cytometry estimated genome sizes, ranging from 1C = 7.670 pg to 18.612 pg, with Aularches miliaris (18.612 pg) being the second largest insect genome reported to date. The repeat content ranged from 51% to 74%, with a mean value of 64.26% of the total genome. The major identified repeat elements included LINE, Ty3_Gypsy, Penelope, Ty1-copia, Helitron, Maverick, and satellite repeats, with LINE elements being the most abundant, constituting 24% to 54% of the total repetitive content in Apalacris varicornis and A. miliaris , respectively. The positive correlation of repetitive content and TEs with genome size suggests that their expansion has contributed to the large genome sizes observed. Satellite DNA analysis identified 65 satDNA families across the eight species. Additionally, phylogenetic analysis of TE protein domains revealed that consensus sequences from the same domain cluster together, suggesting domain-specific evolutionary pathways for TEs in the genome. This study reveals new dynamics into the role of repetitive DNA in genome gigantism as well as other evolutionary mechanisms in the Pyrgomorphidae and Acrididae families of Orthoptera.

We investigate where bottom‐up and top‐down control regulates ecological communities as a mechanism linking ecological gradients to the geography of consumer abundance and biomass. We use standardized surveys of 54 North American grasslands to test alternate hypotheses predicting 100‐fold shifts in the biomass of four common grassland arthropod taxa—Auchenorrhyncha, sucking herbivores, Acrididae, chewing herbivores, Tettigoniidae, omnivores, and Araneae, predators. Bottom‐up models predict that consumer biomass tracks plant quantity (e.g. productivity and standing biomass) and quality (nutrient content) and that ectotherm access to food increases with temperature. Each of the focal trophic groups responded differently to these drivers: the biomass of sucking herbivores and omnivores increased with plant biomass; that of chewing herbivores tracked plant quality; and predator biomass did not depend on plant quality, plant quantity or temperature. The Exploitation Ecosystem Hypothesis is a top‐down hypothesis that predicts a shift from resource limitation of herbivores when plant production is low, to predator limitation when plant production is high. In grasslands where spider biomass was low, herbivore biomass increased with plant biomass, whereas bottom‐up structuring was not evident when spiders were abundant. Furthermore, neither predator biomass nor trophic position (via stable isotope analysis) increased with plant biomass, suggesting predators themselves are top‐down limited. Stable isotope analysis revealed that trophic position of the chewing herbivore and omnivore increased significantly with plant biomass, suggesting these groups increased scavenging and meat consumption in grasslands with higher carbohydrate availability. Taken together, our snapshot sampling documents gradients of food web structure across 54 grasslands, consistent with multiple hypotheses of bottom‐up and top‐down regulation. The authors asked how biomass and trophic position of four major grassland arthropod taxa shift across 54 North American grasslands, sites spanning gradients of climate, nutrient availability and plant productivity. The results find support for both bottom‐up and top‐down processes governing the amount of consumer biomass a grassland can sustain.

This study investigated the potential of indigenous entomopathogenic bacterial (EPB) strains from Egypt to control the two most prevalent locust species, Schistocerca gregaria (Forsskål) (Orthoptera: Acrididae), and Locusta migratoria migratorioides (Reiche & Fairmaire) (Orthoptera: Acrididae). To assess the efficacy of the EPB strains, experiments were conducted in the laboratory, semi field, and field. The results showed that Xenorhabdus nematophila (Thomas et Poinar) BA2 (Enterobacterales: Morganellaceae) and Photorhabdus luminescens (Thomas et Poinar) EGAP3 (Enterobacterales: Morganellaceae) were the most effective strains against S. gregaria and L. migratoria migratorioides in laboratory settings. Under semi-field conditions, X. nematophila BA2 recorded nymphal mortality rates of 89.31% and 85.00% against the 2 nd and 5 th nymph instars of S. gregaria , respectively, and P. luminescens EGAP3 showed nymphal mortality rates of 88.00% and 80.00% against the 2 nd and 5 th nymph instars of S. gregaria , respectively. In field trials, X. nematophila BA2 exhibited the highest nymphal mortality rate of 88.70% at 7 days after spraying. Overall, the findings of this study suggest that X. nematophila BA2 and P. luminescens EGAP3 are promising candidates for environment-friendly, safe locust pest management. Further research is needed to explore and develop these bacteria for commercial use in agriculture.

Ranacris You & Lin, 1983, is a small genus in the subfamily Habrocneminae with an undefined phylogenetic position, exhibiting in previous molecular studies a distant relationship with the genera in the same subfamily but an extremely close relationship with the genus Menglacris Jiang & Zheng, 1994, in another subfamily, Catantopinae. In this study, a taxonomic revision of Ranacris was conducted based on the examination of types and non-type material and the comparison of qualitative and quantitative characters. A morphometric analysis was carried out to test the statistical significance of the quantitative distinguishing characters among Ranacris. A new junior synonym is proposed: R. yunnanensis Mao, Ren & Ou, 2011 = R. jinpingensis Zheng, Lin, Deng & Shi, 2015, syn. nov.

The distribution patterns of 3 rare acridid species, namely Asiotmethis jubatus (Uvarov, 1926) (Pamphagidae), Aeropedellus baliolus Mistshenko, 1951 and Mesasippus arenosus (Bey-Bienko, 1930), are described and compared. In the region, there are the type localities of these species. A. jubatus and M. arenosus are very rare and mainly associated with the dry steppes and the semi-deserts of the region, while A. baliolus are more or less common and distributed over the steppes from their northern boundary up to the southern one. The ecologo-geographic modelling based on the Maxent approach allows to reveal the potential distribution patterns of habitats applicable for each species to forecast possible shifts of species distributions relative to feasible climatic changes according the Shared Socioeconomic Pathway 3-7.0 and the global climate model CNRM-ESM2-1. The comparative analysis of the species distributions, the predicted distributions of suitable conditions and the forecasts of their possible shifts showed that predictions for the endemic steppe species can be quite different. The fore-casts for A. jubatus and M. arenosus based on the species distribution models and the predictions of high greenhouse gas emissions show that they may become relatively prosperous in the middle of the 21st century and the northern boundaries of the optimal parts of their ranges may shift northward. The predictions for A. baliolus show that the species optimal territories may catastrophically reduce in the future (from 265,000 km2 now up to about 18,000 km2 in the middle of the 21st century). As a result, the conservation status of A. baliolus may significantly change, because it will explicitly meet the IUCN criteria of the Vulnerable species.