Earth, Ecology and Environmental sciences

Climate change is influencing population dynamics of several pest insect species leading to the expansion of their range. Range expansion can be driven also by human-mediated dispersal, with the establishment of new insect populations in suitable areas far from their native range. In this process, interactions between insects and their natural enemies can change due to new environmental conditions or to different rate of dispersion. In recent years, pine processionary moth (PPM), one of the main forest pests in the Mediterranean region, is expanding its range favored by both higher winter mean temperatures and accidental human-mediated transportation. Here we outlined the genetic structure of PPM along its range in France using 23 microsatellites loci, characterizing the main patterns of expansion of this species and identifying the source populations of new colonies in the expansion areas. These data can be employed for developing assignment tools to genetically characterize PPM for a quick identification of their origin area. Finally, we developed a new set of microsatellite primers for the PPM specialist egg-parasitoid in order to track its dispersion following its host in the expanding areas. The low genetic variability found, not directly useful for tracking parasitoid expansion, shed light on the role of bacterial endosymbionts in the population genetic structure of this species.

This special issue of Annals of Forest Science compiles ten papers on “Wood formation and tree adaptation to climate”, which were presented at “Le Studium” International Conference in May 2018 in Orléans (France). These papers present observational, experimental and modelling studies investigating the influence of climatic changes on treegrowth from the hour to the century, and from the cell to the landscape.

The project addresses a fundamental problem of forest reaction forecast to the climate change and increasing concentrations of greenhouse gases for the terrestrial ecosystems of the Earth. The main target is to produce a retrospective assessment and a short-term forecast of annual tree-ring productivity (seasonal cell production) of the major conifer plant species in terrestrial forest ecosystems around Eurasia forced by climate and non-climatic factors. The analysis is based on an Interactive Information platform “Global Tree-Ring Growth Evolution Neural Network” (www.vs-genn.ru) and datasets available for the European and Asian dendroecological test-polygons. To achieve the goal of the project, we testified the Vaganov-Shaskin model and its parametrization, as a part of the developing IT system, based on direct long-term field observations for the tree-ring sites in Europe and Asia. As a result of the fellowship four papers were published in high impacted ISI journals. Moreover, a special issue of the ISI journal “Annals of Forest Science” is prepared.

Historical herbaria collected around the world are valuable source of data for studying past communities of folivore organisms and tracking their distributions through the time. Here we examined the world biggest herbarium collection stored in the Muséum National d'Histoire Naturelle (Paris, France) in order to explore past Tilia-feeding endophage complexes and their populations in the Holarctic and clarify the expansion history of the lime leafminer, Phyllonorycter issikii Kumata, 1963 (Lepidoptera: Gracillariidae), an invasive pest in Europe damaging limes, Tilia spp. (Malvaceae).

During this fellowship I performed several greenhouse and laboratory experiments, aiming at assessing the phytotoxic and microbiological effects of microencapsulated peppermint (Mentha x piperita L.) essential oil (MPO). The different doses of MPO were applied in the pot experiments either into vermiculite or top layer of arable soils. As the acceptor-species, I used four maize cultivars, one cultivar of mustard and a weed– lambsquarters (Chenopodium album L.). The microbiological analyses were performed using i) commercial strain of arbuscular fungus Rhizophagus irregularis on maize roots by intersection method, and ii) natural soil-microbiota by FDA biotest. I have found, based on the ED50 analysis, that the phytotoxic effect of MPO is both dose and species as well as soil-medium dependent. The biochemical analyses revealed, that the plants’ response to the application of MPO is typical for the allelopathic stress. The microbiological responses to the MPO applications were not clear enough to conclude and should be continued further.

Peatlands are key ecosystems in the global carbon balance due in part to the slow microbial degradation of the organic matter (OM) in peat soils. Role of peatlands as powerful carbon storage systems may be threatened by climate change, leading to a potential huge release of greenhouse gases to the atmosphere. Our knowledge on the mechanisms behind the microbial OM degradation is still incomplete, and it is also essential to develop better management strategies and mitigate global change impacts. In the frame of the present fellowship, the microbial extracellular enzymatic mechanisms of the OM degradation in peat soil and pore water were studied in a French altered peatland, assessing changes in soil depth and warming effect during an annual cycle. Additionally, to the research programme, during the present fellowship a new technique for the host laboratory was implemented (protocol to measure extracellular enzyme activities in pore water and peat soil), the fellow participated in several conferences and seminars, three publication were or are in the process of being published, and a new project with the host laboratory is in developing.

There is tremendous diversity of interactions between plants and other species. These relationships range from antagonism to mutualism. Interactions of plants with members of their ecological community can lead to a profound metabolic reconfiguration of the plants’ physiology. This reconfiguration can favour beneficial organisms and deter antagonists like pathogens or herbivores. Determining the cellular and molecular dialogue between plants, microbes, and insects, and its ecological and evolutionary implications is important for understanding the options for each partner to adopt an adaptive response to its biotic environment. Moving forward, understanding how such ecological interactions are shaped by environmental change and how we potentially mitigate deleterious effects will be increasingly important. The development of integrative multidisciplinary approaches may provide new solutions to the major ecological and societal issues ahead of us. The rapid evolution of technology provides valuable tools and opens up novel ways to test hypotheses that were previously unanswerable, but requires that scientists master these tools, understand potential ethical problems flowing from their implementation, and train new generations of biologists with diverse technical skills. Here, we provide brief perspectives and discuss future promise and challenges for research on insect–plant interactions building on the 16th International Symposium on Insect–Plant interactions (SIP) meeting that was held in Tours, France (2–6 July 2017). Talks, posters, and discussions are distilled into key research areas in insect–plant interactions, highlighting the current state of the field and major challenges, and future directions for both applied and basic research.