Analysis of Thaumatotibia leucotreta (Lepidoptera; Tortricidae: Olethreutinae) mitochondrial genomes reveal opportunistic host range expansion towards rose

Background: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick, 1913), is a significant pest of various important economic crops and is a EU quarantine pest. In the last decade the pest has been described on rose. In this study we determined whether this shift occurred within specific FCM populations across the Ethiopian zoogeographic region or whether the species opportunistically switches to this novel host as it presents itself. To achieve this we assessed the genetic diversity of complete mitogenomes of T. leucotreta specimens intercepted at import and analysed potential linkages with geographical origin and host species. Results: Genomic, geographical and host information were integrated in a T. leucotreta Nextstrain build which contains 95 complete mitogenomes generated from material intercepted at import between January 2013 and December 2018. Samples represented seven sub-Saharan countries and mitogenomic sequences grouped in six main clades. Discussion: If host strains of FCM would exist, specialization from a single haplotype towards the novel host is expected. Instead, we find specimens intercepted on rose in all six clades. Absence of linkage between genotype and host suggests opportunistic expansion to the new host crop. This underlines risks of introducing new crop species to an area as the effect of pests already present on the new crop might be unpredictable with current knowledge.