Investigating the divergence times and patterns of Cirrospilini (Hymenoptera: Eulophidae), a group of niche specific parasitoids

The tribe Cirrospilini (Eulophidae: Eulophinae) contains some of the most important genera for both native and imported biological control of concealed agricultural pests. For example, Diglyphus contains some of the most significant parasitoids of dipteran leaf miners, Cirrospilus and Semielacher have been released against lepidopteran leaf miners, and Aulogymnus attacks cynipid gall wasps. While coevolution has been used to explain the incredible diversity found in insect-host relationships, recent work has found this is not always the case for parasitoids. Estimates of clade ages and origins can be used to shed light on the evolutionary pathways employed among hosts and parasitoids. Molecular, morphological, and combined analyses all support a monophyletic Eulophidae and Cirrospilini, with all cirrospiline genera except Cirrospilus monophyletic, providing relative stability to perform dating and divergence analyses. Fossil chalcids from Dominican and Baltic amber, used as calibration points, are coupled with COI mitochondrial and 18S and 28S D2-5 ribosomal DNA in this investigation. The results reveal age estimates for the origin of the tribe as much more recent than the majority of its host groups and families. Specialist genera, such as Diglyphus and Aulogymnus, have origins that arise much more recently than their respective specialist hosts and also more recently than the generalist cirrospiline genera used in the analysis, Cirrospilus and Zagrammosoma. The results provide evidence for sequential host colonization as opposed to coevolution as the main evolutionary force for this group of parasitoids, and indicate that specialist parasitoids evolve from within generalist clades.