Large-scale genetic admixture suggests high dispersal in an insect pest, the apple fruit moth

Abstract

Knowledge about population genetic structure and dispersal capabilities is important for the development of targeted management strategies for agricultural pest species. The apple fruit moth, Argyresthia conjugella (Lepidoptera, Yponomeutidae), is a pre-dispersal seed predator. Larvae feed on rowanberries (Sorbus aucuparia), and when rowanberry seed production is low (i.e., inter-masting), the moth switches from laying eggs in rowanberries to apples (Malus domestica), resulting in devastating losses in apple crops. Using genetic methods, we investigated if this small moth expresses any local genetic structure, or alternatively if gene flow may be high within the Scandinavian Peninsula (~850.000 km 2 , 55 o-69 o N). Genetic diversity was found to be high (n = 669, mean He = 0.71). For three out of ten tetranucleotide STRs, we detected heterozygote deficiency caused by null alleles, but tests showed little impact on the overall results. Genetic differentiation between the 28 sampling locations was very low (average FST = 0.016, P < 0.000). Surprisingly, we found that all individuals could be assigned to one of two non-geographic genetic clusters, and that a third, geographic cluster was found to be associated with 30% of the sampling locations, with weak but significant signals of isolation-by-distance. Conclusively, our findings suggest wind-aided dispersal and spatial synchrony of both sexes of the apple fruit moth over large areas and across very different climatic zones. We speculate that the species may recently have had two separate genetic origins caused by a genetic bottleneck after inter-masting, followed by rapid dispersal and homogenization of the gene pool across the landscape. We suggest further investigations of spatial genetic similarities and differences of the apple fruit moth at larger geographical scales, through life-stages, across inter-masting, and during attacks by the parasitoid wasp (Microgaster politus).

Novel insight into lepidopteran phylogenetics from the mitochondrial genome of the apple fruit moth of the family Argyresthiidae

“…In heavy intermast years, the apple fruit moth can hatch to find no host material available and will therefore seek secondary hosts, causing serious damage to apple crops [ 27 ]. A. conjugella is known to have high genetic diversity and a wide distribution in Fennoscandia [ 28 – 30 ], but the lack of complete mitogenomes for A. conjugella and the family Argyresthiidae hampers further studies on systematics, population genetics, taxonomy and evolutionary biology.…”

Novel insight in Lepidoptera phylogenetics from the mitochondrial genome of the apple fruit moth of the family Argyresthiidae

“…In heavy intermast years, the apple fruit moth can hatch to nd no host material available and will therefore seek secondary hosts, causing serious damage to apple crops [27]. A. conjugella is known to have high genetic diversity and a wide distribution in Fennoscandia [28][29][30], but the lack of complete mitogenomes for A. conjugella and the family Argyresthiidae hampers further studies on systematics, population genetics, taxonomy and evolutionary biology.…”

Temporal sampling and network analysis reveal rapid population turnover and dynamic migration pattern in overwintering regions of a cosmopolitan pest

“…Insect pests are abundant in all agricultural regions of the world, and many are difficult to control due to their rapid development of insecticide resistance and active migration. For these pests, molecular evidence of genetic pattern and gene flow may provide important guidance in understanding the colonization history ( Yang et al, 2012 ; Kirk et al, 2013 ; Cao et al, 2019 ; You et al, 2020 ), tracking insecticide resistance ( Taylor et al, 2021 ), and investigating metapopulation dynamics ( Dinsdale et al, 2012 ; Elameen et al, 2020 ; Perera et al, 2020 ). Much work has been done on the genetic structure and phylogeography of widely distributed insect pests, such as Locusta migratoria ( Ma et al, 2012 ), Frankliniella occidentalis ( Yang et al, 2012 ; Cao et al, 2019 ), Nilaparvata lugens (Stål) ( Hu et al, 2019 ) and Plutella xylostella ( You et al, 2020 ).…”

“…Unlike vertebrate migrants, migration circuits of insects can involve multiple generations and experience different levels of connectivity due to their shorter generation time and lower degree of control over movement (flight) directions (Gao et al, 2020). Most population genetic studies of highly dispersive species report a pattern of low genetic differentiation and high gene flow (Jiang et al, 2010;Wei et al, 2013;Elameen et al, 2020), which is not unexpected, but not informative. This is due to the frequently applied genetic parameter N m refers to historical gene flow and thus inadequate for contemporary population dynamics.…”