Pine processionary moths hybridisation in a Mediterranean complex area

The study highlights from a biogeographical perspective the asymmetric gene leakage between two species of pine processional moths in a narrow contact zone in the Mediterranean.

Photo: Donald Hobern - Wikimedia Commons

Pine processionary moths, whose areas of distribution are in contact with western Turkey, are important defoliators in the Mediterranean basin. In this study published in Ecology and Evolution, the authors reveal patterns of hybridisation in this contact area, which may have a significant evolutionary impact on the Thaumetopoea species. The researchers suggest that the dynamics in the species contact zone should be investigated to understand the extent of this impact but also consider that we are now closer to interpreting how this area was formed for the pine processionary moths and how it has been maintained to date.

The article highlights that the distributions and genetic patterns of the moth species studied were strongly influenced by both the climatic oscillations of the Quaternary and the complex geological history of the Aegean region. These species survived the last glacial maximum in disjointed refugia and were found in western Turkey at the edge of recolonization routes. The expansion of the Thaumetopoea wilkinsoni population limited Thaumetopoea pityocampa to the west coast of Turkey. The authors also found evidence of recurrent introgression of male T. wilkinsoni in several populations of T. pityocampa, which implies a transfer of genetic information from one species to another as a result of hybridisation.

The results of this research suggest that some mechanisms of prezygotic isolation, which prevents mating and fertilisation, such as differences in the timing of adult appearance, may be a factor in isolation between sister species. These results will shed light on several issues related to the phenology, morphology and genetics of pine processionary moth populations in and around the contact area.

Full reference:

İpekdal, K., Burban, C., Sauné, L., Battisti, A., Kerdelhué, C. 2020. From refugia to contact: Pine processionary moth hybrid zone in a complex biogeographic setting. Ecology and Evolution, 00: 1–16.

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Kahraman Ipekdal
Kahraman Ipekdal studied biogeography and management of forest pest insect populations; mainly that of the pine processionary moth (Thaumetopoea pityocampa and T. wilkinsoni), the chestnut gall wasp (Dryocosmus kuriphilus) and the western conifer seed bug (Leptoglossus occidentalis).