Biology and Prevalence in Northern Italy of Verrallia aucta (Diptera, Pipunculidae), a Parasitoid of Philaenus spumarius (Hemiptera, Aphrophoridae), the Main Vector of Xylella fastidiosa in Europe

Abstract

The meadow spittlebug, Philaenus spumarius (L.) (Hemiptera Aphrophoridae), the main vector of Xylella fastidiosa Wells et al. in Europe, has few known natural enemies. The endoparasitoid Verrallia aucta (Fallén) (Diptera, Pipunculidae) was first noticed a long time ago but very little is known about its biology and prevalence. In this study, the presence and prevalence of V. aucta were investigated in different regions of northern Italy, both in plain–foothill and montane zones. Parasitic larvae were identified by the dissection of spittlebug adults, P. spumarius and Neophilaenus campestris (Fallén), and by a new species-specific molecular tool targeting the ITS2 and COI genomic regions, developed in this work. A small-scale rearing was set up to gain information on the life cycle of V. aucta on its main host P. spumarius. During the four-year investigation (2016–2019) the pipunculid parasitoid displayed low prevalence, reaching a maximum parasitization rate of 17.5% (calculated over the adult spittlebug season) in vineyards of the Piemonte region. Over the whole period, no significant difference in the prevalence was found between male and female spittlebugs. Collected data and rearing observations suggest that V. aucta is monovoltine and synchronous with P. spumarius, laying eggs in newly emerged adults, developing as an endoparasitoid through two larval stages during the whole summer, and overwintering as a pupa in the soil.

Till evolution do us part: The diversity of symbiotic associations across populations ofPhilaenusspittlebugs

“…Of particular interest was the signal of the specialized dipteran parasitoid, V. aucta , in 24.7% of P. spumarius individuals studied. This ratio is comparable to the 17.5% infection prevalence estimates for P. spumarius populations from the northern Italy (Molinatto et al ., 2020), using diagnostic PCR reactions. Then, the COI amplicon sequencing-based screens of individual insects, besides confirming their identity, can provide believable information on some of their biotic associations.…”

“…Of particular interest was the signal of the specialized dipteran parasitoid, V. aucta, in 24.7% of P. spumarius individuals studied. This ratio is comparable to the 17.5% infection prevalence estimates for P. spumarius populations from the northern Italy (Molinatto et al, 2020), using diagnostic PCR reactions.…”

Xylella fastidiosa in Olive: A Review of Control Attempts and Current Management

“…The predation dynamics of the generalist predator Zelus renardii Kolenati on P. spumarius were reported by Liccardo et al [ 96 ]. Furthermore, Molinatto et al [ 97 ] reported the infestation of field-collected spittlebugs by the parasitoid fly Verrallia aucta Fallén. Data for these natural enemy–vector interactions are preliminary and additional studies are needed to fully understand the degree of parasitoid–prey specificity to avoid non-target effects associated with any augmentative biocontrol measure.…”

Vibrational disruption of feeding behaviors of a vector of plant pathogen

“…the main driver of X. fastidiosa secondary spread within Apulian olive orchards (Cornara et al 2017b(Cornara et al , 2019EFSA et al 2019). Extensive soil tilling, particularly in dry environments, such as Mediterranean olive orchards, may affect soil quality negatively, augment the risk of desertification, and reduce habitats sheltering beneficial arthropods, i.e., predators, parasitoids, and pollinators (Bodino et al 2020;Kairis et al 2013;Karamaouna et al 2019;Mesmin et al 2020;Molinatto et al 2020). Pesticides, on the other side, are not often compatible with integrated pest management techniques and have been listed among the main drivers of terrestrial biodiversity decline (Desneux et al 2007;Brühl & Zaller 2019;Chávez-Dulanto et al 2021;Sánchez-Bayo & Wyckhuys 2019).…”