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Cabbage stem flea beetle : a DNA test to identify resistance to pyrethroids

Today, cabbage stem flea beetle is a major problem on rapeseed in France. Indeed, the efficiency of pyrethroids is very much reduced in some populations.

One of Terres Inovia's missions is to monitor evolution of insect pest susceptibility to insecticide in France. This monitoring is historically carried out through biotests consisting of putting pest populations in contact with different doses of insecticide. This test has the advantage of identifying the level of resistance regardless of the mechanism involved, but the amount of live adults required for the analysis is often limiting. Terres Inovia has developed a genotyping method to identify mutations responsible for resistance to insecticides of the pyrethroid family. This DNA test, which can be carried out on adults or larvae, is now used in addition to biotests and makes it possible to identify so-called target mutation resistance. It has also allowed to greatly increase the sampling.

In the cabbage stem flea bettle, the efficiency of pyrethroids varies greatly depending on the resistance mechanisms involved : efficiency is greatly reduced in the presence of super-kdr mutation and average in the presence of kdr mutation. The super-kdr mutation was first detected in 2015 in east-central France. The monitoring carried out by Terres Inovia shows that populations carrying this mutation are increasingly present on the territory, around the historical sector, but other spots have been identified well beyond this geographical area.

This DNA test is now routinely used by Terres Inovia to monitor coleoptera pest populations in rapeseed, and thus better manage durability of pyrethroids through knowledge of resistance levels and the use of alternatives to pyrethroids in the presence of super KDR mutation. We now propose this service to partners outside France who would like to identify the presence of mutations in their populations of cabbage stem flea beetle, as well as on some species of rapeseed weevils and meligethes. For any information or request for a quote, please contact the genetics and crop protection laboratory of Terres Inovia : labogpc@terresinovia.fr

Contact : Julien CARPEZAT (j.carpezat@terresinovia.fr)