The global changes underway include climate disruption, changes in land use, as well as changes in agricultural practices (notably reduced inputs) and biological invasions. These impose new constraints on insect populations, to which species sometimes respond rapidly. The research work carried out within Area 2 aims to analyse and understand the evolutionary trajectories of the species studied (demography, adaptations, history of invasions), the role of associated microbiota in these trajectories, and to test the sustainability of several innovative management methods, such as the sterile insect technique, agroecological solutions (e.g. push-pull repulsion-attraction strategies) and preventive locust control tools. Theoretical or simulation-based approaches are also being developed to provide new tools for analysing genomic diversity or anticipating crises.
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One of the challenges of our research is to move from analysing the past to predicting future trajectories. |
Research focuses on insects of interest to agronomy and forestry, both native (moths, processionaries, locusts) and invasive (fruit flies, bark beetles, Asian ladybird beetles). They include both fundamental and highly finalised approaches. They involve complementary disciplines and approaches, such as theoretical or statistical development, population genomics, phenotyping and experimental evolution. They concern both natural populations collected or monitored in the field and experimental populations bred under controlled conditions.
Developing strategies to control and/or manage pest populations requires in-depth knowledge of their evolutionary history. In the current context of a gradual reduction in the use of pesticides, it is vital to: (i) identify the geographical origin of pest populations, which is a prerequisite for characterising natural enemies that can then be used as biological control agents; (ii) reconstruct the routes taken by exotic pest species to identify the historical, demographic and genetic factors responsible for the evolutionary success of these populations; (iii) to understand the mechanisms involved in the adaptation of phytophages to their host plants (e.g. in the corn borer Ostrinia nubilalis), or more generally in the expression of their life history traits (e.g. phenology in the pine processionary Thaumetopoea pityocampa; phase polyphenism in the desert locust Schistocerca gregaria), in order to anticipate possible evolutionary dynamics, particularly in the face of changes in agricultural practices and global change.
Population genetics provides powerful tools for inferring evolutionary history based on the analysis of genetic polymorphism. CBGP has widely recognised skills in this field. We are making the most of our mastery and expertise in the technologies associated with the new generations of high-throughput sequencing and genotyping (both in terms of their implementation in the laboratory and their statistical analysis) to characterise the evolutionary history of pest populations. At the same time, we aim to strengthen our skills in quantitative and evolutionary genetics. The aim is to combine genome analysis with the detailed characterisation of phenotypes, in order to determine the genetic basis of the adaptation of insect pests to their biotic and abiotic environment.
Another area of research in Area 2 aims to gain a better understanding of the contemporary dynamics of pest populations. This involves, for example, measurements of life history traits in controlled environments, which provide indirect information on the demography of a species and the role of ecological factors in demographic changes (e.g. the influence of plant cover on phase polyphenism in locusts). At the same time, the development of innovative spatial genetics methods will make it possible to characterise the dispersal capacities of organisms and the role of spatial heterogeneity in the landscape in the fine structuring of populations (e.g. the effect of the landscape and agricultural practices on the population dynamics of the oriental fruit fly Bactrocera dorsalis). All these indirect inferences (based on both genetic and non-genetic approaches) will make it possible to construct spatially explicit mechanistic models of population dynamics, incorporating the knowledge acquired about the life-history traits of species. In particular, these mechanistic models will make it possible to test in silico the effectiveness of alternative techniques to the use of plant protection products for pest management. One of these techniques, entomovectoring, involves using insects to spread biopesticides in pest populations (e.g. using sterile male oriental fruit flies to spread the entomopathogenic fungus Metarhizium).
In addition to indirectly reconstructing the history of populations or their demography, continuing evolution experiments under controlled conditions in the laboratory will provide a better understanding of the dynamics of adaptation and the importance of the constraints and evolutionary compromises that species face, particularly during biological invasions (e.g. in the Asian ladybird Harmonia axyridis and the spotted wing drosophila Drosophila suzukii). Another context in which the study of these dynamics of rapid evolution takes on its full meaning concerns the assessment of the risks associated with the implementation of genetic forcing techniques (gene drive) for the management of pests. These techniques involve the release of genetically modified organisms designed to propagate a variant of interest (e.g. a mutation that reduces fertility) in natural populations. This emerging method of population control raises a number of scientific and societal questions. We are therefore proposing to develop new research programmes aimed at studying the evolutionary dynamics of these genetic constructs in natural populations, in order to better assess the associated environmental risks (emergence of resistance, spread by gene flow in non-target populations, transfers between species, etc.).
Characterising insect microbial communities and gaining a better understanding of the evolutionary ecology of interactions in multi-trophic systems (microbes–insects–host plants) can contribute to the development of insect pest management strategies by exploiting or manipulating these interactions. For example, a better understanding of the role of the intestinal microbiota of phytophagous insects in adaptation to the host plant would make it possible to propose control strategies by manipulating the microbial communities involved (e.g. in the spotted wing drosophila D. suzukii, the European corn borer O. nubilalis or the pine processionary T. pityocampa). In other contexts, the study of interactions between microbes and their hosts could lead to the development of « natural repellents » made up of microbial cocktails, biological control using viral agents, and control by manipulating the biological functions of the pest itself (linked, for example, to immunity).
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Project holder (WP coordination): Charles Perrier
Funding: Fondation Agropolis
This interdisciplinary project combines genetics, ecology and ethnology to better understand the intrinsic, environmental and human factors that have facilitated Carmenta foraseminis recent emergence as a pest insect foraging on cocoa in South America.
