Transcriptomics of selected insecticide-resistant strains of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The fall armyworm Spodoptera frugiperda is a pest of several economically important crops in the Americas that has rapidly developed resistance to major insecticides. Despite this, the molecular mechanisms underlying resistance to the existing synthetic insecticide molecules are not completely characterized. We present a transcriptomic analysis of five selected resistant strains to the pyrethroids lambda-cyhalothrin and deltamethrin, the organophosphate chlorpyrifos, the chitin-synthesis inhibitor lufenuron and the naturalyte spinosad, as a step forward to facilitate further studies in the identification and characterization of genes related to resistance mechanisms. Two 454 EST-datasets, from the midgut and the fat bodies, yielded more than a million reads that were assembled into 4,346 contigs, with an average length of 580 bp, and 24,084 singletons, with an average length of 329 bp. KEGG analysis revealed putative members of the three major metabolic detoxification pathways involved in insecticide resistance. A general database mining from gene families involved in metabolic detoxification revealed 99 transcripts similar to cytochrome P450 monoxygenases, 24 to glutathione-S-transferases (GSTs), 24 to carboxyl-cholinesterases (CCEs), and 20 to target site proteins. Our data represent the first large-scale sequencing effort of the transcriptome of insecticide-resistant strains of S. frugiperda.