Molecular surveillance of resistance in the field
The SMaRT project focuses on an insect pest that is particularly problematic in terms of resistance: the codling moth, Cydia pomonellaThis lepidopteran is the main This lepidopteran is the main pest affecting apple trees worldwide and accounts for two-thirds of all insecticide treatments carried out in French orchards, making this crop one of the most heavily treated. Today, most of the insecticides used against C. pomonella are encountering resistance, including a biopesticide, the granulosis virus (CpGV).
The phenotyping approaches (biotests) currently used to monitor resistance are limited by the cumbersome nature of this method. To improve monitoring, better assess risks, and develop responsive strategies (almost in real time) on a consistent territorial scale, it is essential to have “high-throughput” tests that can quickly analyze a large number of samples at a low cost. Such tools are now within reach thanks to the rise of new sequencing techniques (NGS).
In C. pomonellathe main families of synthetic insecticide molecules encounter specific resistance through mutations in target proteins (target-related resistance, TRR). There are other resistance mechanisms, known as non-specific (non-target-related resistance, NTRR), the most important of which is the detoxification mechanism that confers cross-resistance to virtually all chemical families used. The genetic basis and architecture of NTDR are complex (involving gene families) and are only partially understood in C. pomonella.
The main objective of SMaRT is to organize the conditions for a change of scale in the monitoring of resistance in C. pomonella : from national to regional and from individual to collective actors. Specifically, this will involve (i) completing the identification of the genetic bases of resistance already identified by biotesting in France, and (ii) carry out large-scale sampling in the main production areas in France, with a particular focus on the Basse Vallée de la Durance workshop site, in order to produce a comprehensive overview of the distribution and frequency of resistance through high-throughput sequencing.
This project is funded by ANSES as part of its phytopharmacovigilance program – https://www.anses.fr/fr/content/la-phytopharmacovigilance
