Genome-wide analysis of diamondback moth, Plutella xylostella L., from Brassica crops and wild host plants reveals no genetic structure in Australia

Abstract

Molecular studies of population structure can reveal insight into the movement patterns of mobile insect pests in agricultural landscapes. the diamondback moth, Plutella xylostella L., a destructive pest of Brassica vegetable and oilseed crops worldwide, seasonally colonizes winter canola crops in southern Australia from alternative host plant sources. To investigate movement, we collected 59 P. xylostella populations from canola crops, Brassica vegetable and forage crops and brassicaceous wild host plants throughout southern Australia in 2014 and 2015 and genotyped 833 individuals using RAD-seq for genome-wide analysis. Despite a geographic sampling scale > 3,000 km and a statistically powerful set of 1,032 SNP markers, there was no genetic differentiation among P. xylostella populations irrespective of geographic location, host plant or sampling year, and no evidence for isolation-by-distance. Hierarchical StRU ctU Re analysis at K = 2-5 showed nearly uniform ancestry in both years. cluster analysis showed divergence of a small number of individuals at several locations, possibly reflecting an artefact of sampling related individuals. It is likely that genetic homogeneity within Australian P. xylostella largely reflects the recent colonization history of this species but is maintained through some level of present gene flow. Use of genome-wide neutral markers was uninformative for revealing the seasonal movements of P. xylostella within Australia, but may provide more insight in other global regions where the species has higher genetic diversity. Mobile insect pests regularly colonize annual crops from alternative host plant sources 1-3. Protecting crops from attack by these pests is difficult for pest managers due to the unpredictable nature of seasonal outbreaks, particularly when insecticide resistant genotypes are present 4,5. For mobile insect pests, dispersal among crop and non-crop host plant resources influences both the seasonal dynamics and genetic background of pest populations, with direct consequences for pest management 6-9. Molecular studies of population structure and gene flow can potentially provide insight into patterns of insect movement in agricultural landscapes 10,11. The diamondback moth, Plutella xylostella L., is the most destructive pest of brassicaceous crops worldwide 12,13. It attacks Brassica vegetable crops throughout tropical and temperate regions 14 and in recent decades has become a significant pest of canola crops in temperate regions 4,15-18. The propensity of P. xylostella to evolve insecticide resistance rapidly and a lack of alternative control options has led it to evolve resistance to most pesticides 4. Within Australia, P. xylostella has been a major pest of Brassica vegetable crops since the late 1800s 19 and a sporadic but damaging pest of canola crops since the 1990s following a dramatic expansion of canola production 18. Approximately 3 million hectares of canola is grown annually under a Mediterranean climate in southern Australia 20 , providing vast host resource...

DNA barcode identification of Conopomorpha cramerella (Snellen, 1904) (Lepidoptera: Gracillariidae) and other moths affecting cacao in Papua New Guinea

“…This approach has been reported for other pest Lepidoptera, where next‐generation sequencing approaches have provided unparalleled population genetic resolution of taxonomic lineages defined previously by mitochondrial DNA barcoding (Perry et al . 2018, 2020; Picq et al . 2018).…”

Characterization of a new strain ofMetarhizium novozealandicumwith potential to be developed as a biopesticide

“…The control of this pest costs farmers in the dairy, sheep and beef industries between 41 USD million and 90 USD million annually in lost production (Popay 2008 ). There are also introduced pests as Plutella xylostella (Lepidoptera: Yponomeutidae) commonly known as diamond back moth (DBM), a globally destructive pest of brassicaceous crops, which has developed resistance to many conventional and novel insecticides (Perry et al 2020 ).…”

Migration trajectories of the diamondback moth Plutella xylostella in China inferred from population genomic variation

“…Genetic approaches have been used to trace the historical and recent movements of species across geographical scales 37–40 and thus provide a powerful and efficient method of studying migration trajectories 41–44 . These approaches also have challenges.…”

“…25,32 Additionally, establishing insect migration routes can be challenging because insect migration often occurs nocturnally and at high altitudes, and because the small size of insects means that they cannot be easily tracked using standard observational approaches. 14,[33][34][35][36] Genetic approaches have been used to trace the historical and recent movements of species across geographical scales [37][38][39][40] and thus provide a powerful and efficient method of studying migration trajectories. [41][42][43][44] These approaches also have challenges.…”