France has recently adopted the Ecophyto 2018 plan, which recommends the development of effective biological control programs against pests as alternatives to pesticides. It is acknowledged that successful and safe biological control depends on 1) accurate genetic and phenotypic characterization of the strains of natural enemies released; 2) strong knowledge of their life-history traits, strategies of host exploitation and population dynamics; 3) good understanding of the processes determining their successful establishment. Nevertheless, such studies are rarely, if ever, conducted, which hampers our ability to implement efficient programs against pests. During this project, joining our complementary skills, we will tackle these topics, thereby addressing key questions in evolutionary biology about speciation, hybridization, adaptation, specialisation, and interaction dynamics.
We will focus on four species complexes of the genus Trichogramma (Hymenoptera), one of the most studied and commercialized groups to control pests of major economic importance in Europe. Nevertheless Trichogramma are frequently released without taxonomic, genetic, phenotypic or behaviour characterization and in-depth risk assessment study. This practice must be improved to comply with a recent decree adopted in France stipulating that macro-organisms must be precisely characterized before released, to ensure traceability and prevent unintended effects. Trichogramma species complexes are poorly understood and entities with weak reproductive barriers may exist. Strains display significant inter- and intra-population variations in biological traits that are influenced by environmental factors, and several traits important for biocontrol success have been poorly documented (e.g. movement and dispersal capacities). Infections by symbionts can influence individual fitness, reproductive isolation and ecological specialization, but there is little data on most symbionts associated with Trichogramma species. Finally their evolutionary history is poorly known. Using novel and powerful methods, we will:
1) Investigate species limits, phenotype biocontrol traits and quantify gene flow and evolutionary potential within the species complexes. We will characterize sampled strains and those already commercialized, using high-throughput methods of genotyping (RAD-sequencing), phenotyping (high-throughput ethomics), and endosymbiont screening, still rarely used, though informative and powerful.
2) Study the impact at the population level of the individually-characterized traits
3) Analyse the evolutionary processes at play when populations are introduced into a novel and complex habitat, either alone or in pluri-specific combinations.
Understanding the selective pressure driving Trichogramma evolution (e.g. how strategies of host exploitation have evolved) and developing knowledge on phenotypes, hybridization potential of released strains with each others and local fauna or on the relative influence of competition and facilitation for parasitoid communities organization should allow us to i) better select appropriate strains for targeted biocontrol, ii) maximise the chances of safely introducing agents into a new habitat and iii) better anticipate their impact and modify control strategy if needed. Biological control often involves public-private partnerships. These collaborations are essential as (i) agents are produced and sold by private firms and (ii) identification and evaluation of biocontrol candidates require scientific skills. This is why we included a work package dedicated to the maintenance of characterized strains and knowledge transfer towards stake-holders (ecologists, agricultural practitioners, private companies) through a web-interfaced database. This WP will be organized around the recently established Biological Resource Center devoted to biological control using macro-organisms and hosted by ISA.
Project ID: ANR-14-CE18-0002
Monsieur Jean-Yves Rasplus (UMR 1062 Centre de Biologie et de Gestion des Populations)
The project coordinator is the author of this abstract and is therefore responsible for the content of the summary. The ANR disclaims all responsibility in connection with its content.