Genomic variation among species is commonly driven by transposable element (TE) invasion; thus, the pattern of TEs in a genome allows drawing an evolutionary history of the studied species. This paper reports in vitro and in silico detection and characterization of irritans mariner-like elements (MLEs) in the genome and transcriptome of Bactrocera oleae (Rossi) (Diptera: Tephritidae). Eleven irritans MLE sequences have been isolated in vitro using terminal inverted repeats (TIRs) as primers, and 215 have been extracted in silico from the sequenced genome of B. oleae. Additionally, the sequenced genomes of Bactrocera tryoni (Froggatt) and Bactrocera cucurbitae (Diptera: Tephritidae) have been explored to identify irritans MLEs. A total of 129 sequences from B. tryoni have been extracted, while the genome of B. cucurbitae appears probably devoid of irritans MLEs. All detected irritans MLEs are defective due to several mutations and are clustered together in a monophyletic group suggesting a common ancestor. The evolutionary history and dynamics of these TEs are discussed in relation with the phylogenetic distribution of their hosts. The knowledge on the structure, distribution, dynamic, and evolution of irritans MLEs in Bactrocera species contributes to the understanding of both their evolutionary history and the invasion history of their hosts. This could also be the basis for genetic control strategies using transposable elements.

Mariner-like elements (MLEs) are class II transposons belonging to the Tc1-mariner family, that have successfully invaded many insect genomes. In the current study, the availability of the Hessian fly Mayetiola destructor genome has enabled us to perform in silico analysis of MLEs using as query the previously described mariner element (Desmar1) belonging to mauritiana subfamily. Eighteen mauritiana-like elements were detected and were clustered into three main groups named Desmar1-like, MauCons1 and MauCons2. Subsequently, in vitro analysis was carried out to investigate mauritiana-like elements in M. destructor as well as in Mayetiola hordei using primers designed from TIRs of the previously identified MLEs. PCR amplifications were successful and a total of 12 and 17 mauritiana-like elements were discovered in M. destructor and M. hordei, respectively. Sequence analyses of mauritiana-like elements obtained in silico and in vitro have showed that MauCons1 and MauCons2 elements share low similarity with Desmar1 ranging from 50% to 55% suggesting different groups under mauritiana subfamily have invaded the genomes of M. destructor and M. hordei. These groups are likely inherited by vertical transmission that subsequently underwent different evolutionary histories. This work describes new mauritiana-like elements in M. destructor that are distinct from the previouslydiscovered Desmar1 and provides the first evidence of MLEs belonging to mauritiana subfamily in M. hordei.