Transcriptome differential co-expression reveals distinct molecular response of fall-armyworm strains to DIMBOA.

Background: 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), the main benzoxazinoid found in corn, elicits variable larval responses from different pest moths. For the widespread and highly polyphagous Spodoptera frugiperda (Lepidoptera: Noctuidae), the fall-armyworm (FAW), DIMBOA acts as a feeding stimulant and improves larval growth at low concentrations. The FAW present two host plant-related strains, corn and rice strains, related to host preference on corn and other Graminae or rice.

Loci under selection and markers associated with host plant and host-related strains shape the genetic structure of Brazilian populations of Spodoptera frugiperda (Lepidoptera, Noctuidae).

We applied the ddRAD genotyping-by-sequencing technique to investigate the genetic distinctiveness of Brazilian populations of the noctuid moth Spodoptera frugiperda, the fall armyworm (FAW), and the role of host-plant association as a source of genetic diversification. By strain-genotyping all field-collected individuals we found that populations collected from corn were composed primarily of corn-strain individuals, while the population collected from rice was composed almost entirely of rice-strain individuals. Outlier analyses indicated 1,184 loci putatively under selection (ca.