Transcriptional differences between the two host strains of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Authors: ORSUCCI, MARION - University Of Montpellier; MONE, YVES - University Of Montpellier; AUDIOT, PHILLIPPE - University Of Montpellier; GIMENEZ, SYLVIE - University Of Montpellier; NHIM, SANDRA - University Of Montpellier; NAIT-SAIDI, RIMA - University Of Montpellier; FRAYSSINET, MARIE - University Of Montpellier; DUMONT, GUILLAUME - University Of Montpellier; BOUDON, JEAN-PAUL - University Of Montpellier; VABRE, MARIN - University Of Montpellier; RIALLE, STEPHANIE - University Of Montpellier; KOUAL, RACHID - University Of Montpellier; KERGOAT, GAEL - University Of Montpellier; Nagoshi, Rodney; Meagher, Robert - Rob; D'ALENCON, EMMANUELLE - University Of Montpellier; NEGRE, NICHOLAS - University Of Montpellier

Submitted to: Peer Community in Evolutionary Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2021
Publication Date: 1/3/2022
Citation: Orsucci, M., Mone, Y., Audiot, P., Gimenez, S., Nhim, S., Nait-Saidi, R., Frayssinet, M., Dumont, G., Boudon, J., Vabre, M., Rialle, S., Koual, R., Kergoat, G., Nagoshi, R.N., Meagher Jr, R.L., D'Alencon, E., Negre, N. 2022. Transcriptional differences between the two host strains of Spodoptera frugiperda (Lepidoptera: Noctuidae). Peer Community in Evolutionary Biology. 2:1-19. Article e1. https://doi.org/10.24072/pcjournal.77.
DOI: https://doi.org/10.24072/pcjournal.77

Interpretive Summary: The fall armyworm (FAW), is an important agricultural pest in the Americas and an emerging pest in sub-Saharan Africa, India and East-Asia, causing damage to major crops such as corn, sorghum and soybean. Scientists with the University of Montpellier in collaboration with scientists from USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, conducted genetic studies to determine the impact of plant diet on several traits linked to the fitness of field collected larvae in different host habitats for the two host strains. The findings indicate that the corn strain is specialized to corn as a preferred host, whereas rice strain does not appear to have a preferred host plant. These studies suggest that control measures can be more localized or focused depending on which strain is involved in an outbreak of the pest.

Technical Abstract: Spodoptera frugiperda, the fall armyworm (FAW), is an important agricultural pest in the Americas and an emerging pest in sub-Saharan Africa, India and East-Asia, causing damage to major crops such as corn, sorghum and soybean. While FAW larvae are considered polyphagous, differences in diet preference have been described between two genetic variants: the corn strain (sf-C) and the rice strain (sf-R). These two strains are sometimes considered as distinct species, raising the hypothesis that host plant specialization might have driven their divergence. To test this hypothesis, we first performed controlled reciprocal transplant (RT) experiments to address the impact of plant diet on several traits linked to the fitness of the sf-C and sf-R strains. The phenotypical data suggest that sf-C is specialized to corn. We then used RNA-Seq to identify constitutive transcriptional differences between strains, regardless of diet, in laboratory as well as in natural populations. We found that mitochondrial transcription is the main difference between the two strains. Since mitochondrial genotypes are also the main genetic variation between the strains, we propose that the mitochondrial genome is the main target of selection between the two strains.