Although it is well known that insects are sensitive to temperature, how they will be affected by ongoing global warming remains uncertain because these responses are multifaceted and ecologically complex. We reviewed the effects of climate warming on 31 globally important phytophagous (plant‐eating) insect pests to determine whether general trends in their responses to warming were detectable. We included four response categories (range expansion, life history, population dynamics, and trophic interactions) in this assessment. For the majority of these species, we identified at least one response to warming that affects the severity of the threat they pose as pests. Among these insect species, 41% showed responses expected to lead to increased pest damage, whereas only 4% exhibited responses consistent with reduced effects; notably, most of these species (55%) demonstrated mixed responses. This means that the severity of a given insect pest may both increase and decrease with ongoing climate warming. Overall, our analysis indicated that anticipating the effects of climate warming on phytophagous insect pests is far from straightforward. Rather, efforts to mitigate the undesirable effects of warming on insect pests must include a better understanding of how individual species will respond, and the complex ecological mechanisms underlying their responses.

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1. Winter temperatures in northern latitudes are predicted to increase markedly as a result of ongoing climate change, thus making the invasion of new insect defoliators possible. The establishment of new outbreak pest species may have major effects on northern ecosystems that are particularly sensitive to disturbances. 2. Effects of winter minimum temperatures under field and laboratory conditions were examined and limitations by minimum temperatures on future range expansion were investigated for invasive [Operophtera brumata (Lepidoptera: Geometridae)] and potentially invasive [Agriopis aurantiaria (Lepidoptera: Geometridae)] birch‐feeding forest pests. The results for the studied invasive and potentially invasive moths were compared with the parameters of the resident moth species Epirrita autumnata (Lepidoptera: Geometridae). 3. The results showed tolerated critical temperatures of the invader (O. brumata) and the resident (E. autumnata) were more similar (differing only by 1 °C), whereas the potential invader (A. aurantiaria) was much less tolerant of cold temperatures. Although describing different stages of overwintering, results were consistent between laboratory and field studies except for those at one field location, at which other abiotic conditions are suggested to have significant influence on moth egg survival. 4. Based on the present results and expected changes in winter temperatures over the next 30 years, the range expansion of an established invasive species may be predicted. No limitations were found regarding the possible future invasion of a new pest species to northern Fennoscandia. The importance of studying a species' whole overwintering period is highlighted and further studies devoted to the effects of other abiotic factors in addition to the effects of temperature are suggested.

Due to their submerged and cryptic lifestyle, the vast majority of fungal species are difficult to observe and describe morphologically, and many remain known to science only from sequences detected in environmental samples. The lack of practices to delimit and name most fungal species is a staggering limitation to communication and interpretation of ecology and evolution in kingdom Fungi. Here, we use environmental sequence data as taxonomical evidence and combine phylogenetic and ecological data to generate and test species hypotheses in the class Archaeorhizomycetes (Taphrinomycotina, Ascomycota). Based on environmental amplicon sequencing from a well-studied Swedish pine forest podzol soil, we generate 68 distinct species hypotheses of Archaeorhizomycetes, of which two correspond to the only described species in the class. Nine of the species hypotheses represent 78% of the sequenced Archaeorhizomycetes community, and are supported by long read data that form the backbone for delimiting species hypothesis based on phylogenetic branch lengths. Soil fungal communities are shaped by environmental filtering and competitive exclusion so that closely related species are less likely to co-occur in a niche if adaptive traits are evolutionarily conserved. In soil profiles, distinct vertical horizons represent a testable niche dimension, and we found significantly differential distribution across samples for a well-supported pair of sister species hypotheses. Based on the combination of phylogenetic and ecological evidence, we identify two novel species for which we provide molecular diagnostics and propose names. While environmental sequences cannot be automatically translated to species, they can be used to generate phylogenetically distinct species hypotheses that can be further tested using sequences as ecological evidence. We conclude that in the case of abundantly and frequently observed species, environmental sequences can support species recognition in the absences of physical specimens, while rare taxa remain uncaptured at our sampling and sequencing intensity.