Location: Systematic Entomology LaboratoryTitle: A novel reference dated phylogeny for the genus Spodoptera Guenée (Lepidoptera: Noctuidae: Noctuinae): new insights into the evolution of a pest-rich genus
|KERGOAT, GABEL - Non ARS Employee|
|LE RU, BRUNO - University Of Nairobi|
|MEAGHER, ROBERT - Florida Department Of Agriculture|
|ZILLI, ALBERTO - London Natural History Museum|
|MITCHELL, A. - Australian Museum|
|CLAMENS, ANNE-LAUREN - Non ARS Employee|
|BARBUT, JEROME - University Of Paris|
|GIMENEZ, SILVIE - University Of Montpellier|
|NEGRE, NICOLAS - University Of Montpellier|
|D'ALENCON, EMMANUELLE - University Of Montpellier|
|NAM, KIWOONG - University Of Montpellier|
Submitted to: Molecular Phylogenetics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2021
Publication Date: 4/14/2021
Citation: Kergoat, G., Goldstein, P.Z., Le Ru, B., Meagher, R., Zilli, A., Mitchell, A., Clamens, A., Barbut, J., Gimenez, S., Negre, N., D'Alencon, E., Nam, K. 2021. A novel reference dated phylogeny for the genus Spodoptera Guenée (Lepidoptera: Noctuidae: Noctuinae): new insights into the evolution of a pest-rich genus. Molecular Phylogenetics and Evolution. 161:107161.
Interpretive Summary: The genus Spodoptera includes numerous species of high economic impact, including the Fall Armyworm (FAW) which has spread across multiple continents in recent years. This is first analysis of the relationships among species in this genus based on complete sequences of the mitochondrial genome and the first attempt to use estimate the ages of these species using molecular data. The results strongly suggest a means for examining the evolutionary origins of behaviors that lead to outbreak species such as FAW. This work is of interest to agriculturalists, pest control scientists, and entomologists.
Technical Abstract: The noctuid genus Spodoptera currently consists of 31 species with varied host plant breadths, ranging from monophagous and oligophagous non-pest species to polyphagous pests of economic importance. Several of these pest species have become major invaders, colonizing multiple continents outside their native range. Such is the case of the infamous fall armyworm, Spodoptera frugiperda (J.E. Smith), which includes two recognized host strains that have not been treated as separate species. Following its accidental introduction to Africa in 2016, it quickly spread through Africa and Asia to Australia. Given that half the described Spodoptera species cause major crop losses, comparative genomics studies of several Spodoptera species have highlighted major adaptive changes in genetic architecture, possibly relating to their pest status. Several recent population genomics studies conducted on two species enable a more refined understanding of their population structures, migration patterns and invasion processes. Despite growing interest in the genus, the taxonomic status of several Spodoptera species remains unstable and evolutionary studies suffer from the absence of a robust and comprehensive dated phylogenetic framework. We generated mitogenomic data for 14 Spodoptera taxa, which are combined with data from 15 noctuoid outgroups to generate a resolved mitogenomic backbone phylogeny using both concatenation and multi-species coalescent approaches. We combine this backbone with additional mitochondrial and nuclear data to improve our understanding of the evolutionary history of the genus. We also carry out comprehensive dating analyses, which implement three distinct calibration strategies based on either primary or secondary fossil calibrations. Our results provide an updated phylogenetic framework for 28 Spodoptera species, identifying two well-supported ecologically diverse clades that are recovered for the first time. Well-studied larvae in each of these clades are characterized by differences in mandibular shape, with one clade’s being more specialized on silica-rich C4 grasses. Interestingly, the inferred timeframe for the genus suggests an earlier origin than previously thought for the genus: about 17-18 million years ago.