Spodoptera frugiperda is a noctuid moth also called "fall armyworm", as there are can be so many caterpillars that they form "carpets" on the ground—much like an army on the move. These armyworm attacks affect more than 100 plants, including cultivated ones (corn, rice, sorghum, cotton, soy). It is very common in both North and South America. FAO estimates that Brazil alone spends US$600 million each year on controlling infestations. Since January 2016, it has become invasive in Africa and it is now threatening the European continent.

As part of the international public consortium Fall Armyworm and in collaboration with CEA and INRIA, researchers at INRA have sequenced the genome of Spodoptera frugiperda. First they studied genes involved in the recognition of host plants, which are sources of food as well as choice of where to lay eggs. The scientists revealed a surprisingly large number of genes corresponding to the detection of toxins, or bitter compounds produced by plants. Then they looked at other families of genes needed to counter the chemical defenses that plants overproduce when under attack. Here too, an expansion of the genes, compared to their congeners, has been discovered. These are the same genes that can be involved in insecticide resistance.

Making such data available to the international scientific community will help identify which variant of the butterfly is currently invading Africa. This research will also lead to new means of biological control, and deepen the current understanding of the mechanisms underlying insecticide resistance.