Genetic basis of camouflage in an alpine plant and its long-term co-evolution with an insect herbivore
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Temporal dynamics and global flows of insect invasions in an era of globalization
Human-mediated transport has led to the establishment of more than 6,700 non-native insect species with wide-ranging effects on ecosystems, economies and human health. Understanding how different aspects of globalization affect the spread of non-native insects is crucial to reducing their effects. In this Review, we explore current and historical patterns, drivers and dynamics of global insect invasions facilitated by humans since prehistory. Multiple aspects of the history of globalization have influenced invasion dynamics, including the spread of agricultural practices in the Neolithic period, the advent of early empires and their trade routes, colonization, geopolitical events, wars and economic crises. Technological innovations such as steam ships, containerization and the internet have further accelerated global insect invasions. Spatial invasion patterns are characterized by frequent secondary spread via bridgehead populations, asymmetric intercontinental species flows originating disproportionally from Europe, and biotic homogenization of communities. Insect invasions are predicted to increase dramatically and their dynamics will shift, especially with the opening of trade routes and introduction pathways. Inspection at ports of entry and early detection systems are crucial to inform mitigation efforts. Future interdisciplinary collaborations will integrate knowledge from diverse and emerging data sources and technologies, advancing our understanding of insect invasion biology.
Methane emissions from thermokarst lakes must emphasize the ice-melting impact on the Tibetan Plateau
Thermokarst lakes, serving as significant sources of methane (CH4), play a crucial role in affecting the feedback of permafrost carbon cycle to global warming. However, accurately assessing CH4 emissions from these lakes remains challenging due to limited observations during lake ice melting periods. In this study, by integrating field surveys with machine learning modeling, we offer a comprehensive assessment of present and future CH4 emissions from thermokarst lakes on the Tibetan Plateau. Our results reveal that the previously underestimated CH4 release from lake ice bubble and water storage during ice melting periods is 11.2 ± 1.6 Gg C of CH4, accounting for 17 ± 4% of the annual total release from lakes. Despite thermokarst lakes cover only 0.2% of the permafrost area, they annually emit 65.5 ± 10.0 Gg C of CH4, which offsets 6.4% of the net carbon sink in alpine grasslands on the plateau. Considering the loss of lake ice, the expansion of thermokarst lakes is projected to lead to 1.1–1.2 folds increase in CH4 emissions by 2100. Our study allows foreseeing future CH4 emissions from the rapid expanding thermokarst lakes and sheds new lights on processes controlling the carbon-climate feedback in alpine permafrost ecosystems.
Gut microbiomes of cycad-feeding insects tolerant to β-methylamino-L-alanine (BMAA) are rich in siderophore biosynthesis
Ingestion of the cycad toxins β-methylamino-L-alanine (BMAA) and azoxyglycosides is harmful to diverse organisms. However, some insects are specialized to feed on toxin-rich cycads with apparent immunity. Some cycad-feeding insects possess a common set of gut bacteria, which might play a role in detoxifying cycad toxins. Here, we investigated the composition of gut microbiota from a worldwide sample of cycadivorous insects and characterized the biosynthetic potential of selected bacteria. Cycadivorous insects shared a core gut microbiome consisting of six bacterial taxa, mainly belonging to the Proteobacteria, which we were able to isolate. To further investigate selected taxa from diverging lineages, we performed shotgun metagenomic sequencing of co-cultured bacterial sub-communities. We characterized the biosynthetic potential of four bacteria from Serratia, Pantoea, and two different Stenotrophomonas lineages, and discovered a suite of biosynthetic gene clusters notably rich in siderophores. Siderophore semi-untargeted metabolomics revealed a broad range of chemically related yet diverse iron-chelating metabolites, including desferrioxamine B, suggesting the occurrence of an unprecedented desferrioxamine-like biosynthetic pathway that remains to be identified. These results provide a foundation for future investigations into how cycadivorous insects tolerate diets rich in azoxyglycosides, BMAA, and other cycad toxins, including a possible role for bacterial siderophores.
Endosymbionts modulate virus effects on aphid-plant interactions
Vector-borne pathogens frequently modify traits of their primary hosts and vectors in ways that influence disease transmission. Such effects can themselves be altered by the presence of other microbial symbionts, yet we currently have limited understanding of these interactions. Here we show that effects of pea enation mosaic virus (PEMV) on interactions between host plants and aphid vectors are modulated by the presence of different aphid endosymbionts. In a series of laboratory assays, we found strong interactive effects of virus infection and endosymbionts on aphid metabolomic profiles, population growth, behavior, and virus transmission during aphid feeding. Furthermore, the strongest effects—and those predicted to favor virus transmission—were most apparent in aphid lines harboring particular endosymbionts. These findings show that virus effects on host-vector interactions can be strongly influenced by other microbial symbionts and suggest a potentially important role for such interactions in disease ecology and evolution.
Metabolite-driven mechanisms reveal chemical ecology of Lehmann Lovegrass (Eragrostis lehmanniana) invasion in North American semi-arid ecosystems
Invasive plants threaten global ecosystems, yet traditional analyses of functional traits cannot fully explain their dominance over co-occurring natives. Metabolomics offers insights into plant invasions, but single-technique studies often miss critical biochemical mechanisms. We employ a multimodal metabolomics approach (¹H NMR, LC MS/MS, FT-ICR-MS, and MALDI-MSI) to investigate the biochemical basis of Lehmann lovegrass (Eragrostis lehmanniana) invasion in semi-arid North America, comparing it with a co-occurring native grass, Arizona cottontop (Digitaria californica). Our analysis reveals three metabolomic traits of Lehmann lovegrass compared to Arizona cottontop: Enhanced nitrogen allocation in shoots, reduced defensive metabolites in root layers; and increased root exudate modulation under stress conditions. These traits suggest Lehmann lovegrass succeeds through adaptation to increasing aridity rather than direct competition, demonstrating adaptation to nutrient-poor environments and high phenotypic plasticity in response to increasing aridity. This integrated metabolomic approach provides new mechanistic insights into invasion ecology and plant adaptation under environmental change.
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