Abstract
Simple SummaryParasitoid wasps in the family Braconidae are generally highly specialized and can be used as agents for biological control of arthropod pests. Psyttalia concolor, Psyttalia humilis and Psyttalia lounsburyi parasitize the larvae of the olive fruit fly (Bactrocera oleae), the most damaging pest of cultivated olives in the world. Psyttalia concolor is native to the Mediterranean, and P. humilis and P. lounsburyi are native to sub-Saharan Africa. Despite their potential for agricultural pest control, these species have been poorly characterized at the genetic level. We sequenced the mitochondrial genome of the three species and compared its organization with other Braconidae. Psyttalia had a unique gene rearrangement involving the positions of transfer RNA genes. We also present a phylogenetic reconstruction of the Braconidae and confirm the phylogenetic placement of Psyttalia in the subfamily Opiinae. The family Braconidae consists mostly of specialized parasitoids, some of which hold potential in biocontrol of agricultural pests. Psyttalia concolor, Psyttalia humilis and Psyttalia lounsburyi are parasitoids associated with Bactrocera oleae, a major pest of cultivated olives. The native range of Psyttalia concolor is the Mediterranean, and P. humilis and P. lounsburyi are native to sub-Saharan Africa. This study reports the mitochondrial genomes of the three species, thus laying the foundation for mitogenomic analyses in the genus Psyttalia. Comparative mitogenomics within Braconidae showed a novel gene arrangement in Psyttalia in involving translocation and inversion of transfer RNA genes. The placement of Psyttalia in the subfamily Opiinae was well-supported, and the divergence between Psyttalia and its closest relative (Diachasmimorpha longicaudata) was at ~55 MYA [95% highest posterior density (HPD): 34–83 MYA]. Psyttalia lounsburyi occupied the most basal position among the three Psyttalia, having diverged from the other two species ~11 MYA (95% HPD: 6–17 MYA). Psyttalia concolor and P. humilis were recovered as sister species diverged at ~2 MYA (95% HPD: 1.1–3.6 MYA). This phylogeny combining new sequences and a set of 31 other cyclostomes and non-cyclostomes highlights the importance of a comprehensive taxonomic coverage of Braconidae mitogenomes to overcome the lack of robustness in the placement of several subfamilies.
Highlights
The family Braconidae is a species-rich group that includes 40 subfamilies represented by over 1000 genera and more than 19,000 known species [1,2]
Psyttalia lounsburyi has been reported in Kenya and South Africa, where it was recovered from B. oleae infesting wild olives [20,22]
The present work lays the foundation for mitogenomics in the genus Psyttalia, and the clarification of the phylogenetic relationships of P. concolor, P. lounsburyi and P. humilis within Braconidae
Summary
The family Braconidae is a species-rich group that includes 40 subfamilies represented by over 1000 genera and more than 19,000 known species [1,2]. Psyttalia lounsburyi has been reported in Kenya and South Africa, where it was recovered from B. oleae infesting wild olives [20,22]. Psyttalia concolor has reportedly been reared from medfly (C. capitata) infesting argan fruit (Argania spinosa L., Sapotaceae) in Morocco [30] Those specimens were not subjected to DNA-based analyses, and the indistinguishability between P. humilis and P. concolor demands caution in the identification of Psyttalia, especially if emerged from hosts other than B. oleae, which is presently the only confirmed host of P. concolor [21]. P. humilis and P. lounsburyi, but the introductions had limited success, as only P. lounsburyi, the most specialized of the two parasitoids was recovered [18,33,34] Despite their potential utility and interesting evolutionary specialization as parasitoids of the olive fruit fly, P. concolor, P. humilis and P. lounsburyi have not been fully characterized at the level of the mitochondrial sequence. The present work lays the foundation for mitogenomics in the genus Psyttalia, and the clarification of the phylogenetic relationships of P. concolor, P. lounsburyi and P. humilis within Braconidae
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