Prevalence of the endoparasitoid Verrallia aucta in Central Scotland: A potential biocontrol for Philaenus spumarius (Hemiptera, Aphrophoridae), an important vector of Xylella fastidiosa

Xylella fastidiosa is a bacterial plant pathogen transmitted by xylem-feeding insect vectors such as the meadow spittlebug, Philaenus spumarius (Hemiptera, suborder Auchenorrhyncha, family Aphrophoridae). Although X. fastidiosa is not currently found in the UK, methods for reducing vector populations will play an important role in controlling the spread of disease in the event X. fastidiosa is introduced. The endoparasitoid big-headed fly, Verrallia aucta Fallen 1817 (Diptera, Pipunculidae), is a parasite specific to Aphrophoridae and has the potential to be used as a biological control agent; however, there is limited information available on its current presence and prevalence in Scotland. This study used Sanger sequencing and morphology to identify V. aucta within Central Scotland. Additionally, four species of adult Auchenorrhyncha collected during Summer 2021 from sites across Central Scotland were molecularly screened for presence of V. aucta parasitism. Sex and habitat prevalence in V. aucta parasitism in P. spumarius was also examined. Findings from this study demonstrate V. aucta is present in Scotland and specifically parasitizes Aphrophoridae. Parasitism rates of P. spumarius ranged between 17% and 57%, with both male and female adult P. spumarius parasitized equally and rates differing according to habitat. Together, this study improved our knowledge and understanding of the parasitism rate, distribution and nature of V. aucta parasitism in Scotland. Further work is required to strengthen our understanding of the host-parasite relationship and take the first steps towards using V. aucta as a natural biocontrol agent to protect plants against transmission of X. fastidiosa.

Automated summary

This study identified the presence of V. aucta in Central Scotland using Sanger sequencing and morphology, and investigated its parasitism on P. spumarius. The findings revealed the existence of V. aucta in Scotland and its ability to parasitize Aphrophoridae, with parasitism rates varying according to habitat.