Gall wasps are plant-associated insects that cause their host plants to form novel and phenotypically diverse plant structures (galls), within which their offspring develop (Melika 2006). Gall wasps are usually host-specific, attacking one host plant species, or several species in the same genus (Melika 2006). Some gall wasps have been introduced outside their endemic ranges along with their host plants, and some of these species, such as Dryocosmus kuriphilus Yasumatsu and Phanacis hypochoeridis (Kieffer), have become “global invaders” and are commonly encountered across multiple continents (Buffington et al. 2020, Avtzis et al. 2018, Nastasi & Deans 2021). Further adding to knowledge of gall wasp introductions, we report the first record of Neaylax verbenacus (Nieves-Aldrey, 1988) in Canada, representing the first record of this genus and species in North America. This species is native to Mediterranean Europe (Nieves-Aldrey 1988, 2001, Melika 2006); our report represents the first record outside of its known endemic range.
Three adult female Neaylax verbenacus were observed and collected off Salvia × digenea plants in an urban garden in Winnipeg, Manitoba, Canada. Galls were subsequently observed on the fruits, the previously known plant organ galled by N. verbenacus. Both adult wasps and galls were posted as observations to the community science platform iNaturalist (https://inaturalist.org). Adult wasps were first observed on host plants on 5 June 2024, and galls were first observed on 7 July 2024. Collections and observations occurred throughout June, July, and August 2024 (GBIF 2024).
Adult wasps are deposited at PSUC (Frost Entomological Museum, The Pennsylvania State University, University Park, PA, USA).
The Neaylax specimens from Winnipeg (Fig. 1) are N. verbenacus based on the diagnostic characters given by Nieves-Aldrey (1988, 2001) and Melika (2006), particularly the lack of a strong median mesoscutal impression, the complete notauli (Fig. 2), the open fore wing marginal cell, and the lack of a pilose patch on the second metasomal tergite. This combination of characters distinguishes Neaylax from all other Nearctic Aulacideini (Nastasi et al. 2024a, 2024b). Our specimens perfectly agree with the SEM images in Nieves-Aldrey (2022), especially in characters of the mesosoma. The author of the species also confirmed the identification after examining our images (see acknowledgments).
Known hosts for N. verbenacus are Salvia pratensis L. and S. verbenaca L. (Nieves-Aldrey 1988, 2001). The host plant recorded here, S. × digenea, is a hybrid of disputed parentage, but may correspond to a cross of S. amplexicaulis Lam. with either S. nemorosa L. or S. × sylvestris L. Together, these and several other sage species form a complex group that is often treated simply as S. nemorosa (Stace et al. 2015). Salvia nemorosa was previously known to host two Neaylax species, N. salviae (Giraud) and N. nemorosae (Balás), but N. verbenacus has not yet been recorded from this plant or S. × digenea (Melika 2006).
The introduction of Neaylax verbenacus to Canada was probably accidental. Neaylax have been intercepted at US ports of entry on sage plants originating from Egypt and Israel (M. Buffington, pers. comm.). No further records of adults or galls were previously known in North America. After discussing findings with members of the community, the second author deduced that the plants on which Neaylax were observed were purchased from a market and distributed by prominent nurseries in Manitoba. Whether the purchased plants were hosts of gall wasps, or gall wasps were already present in the area is unclear. Given that observations of N. verbenacus in Winnipeg were all relatively closely located, it is possible that these individuals represent a localized introduction rather than an established population.
Michael Skvarla provided excellent recommendations for structuring the manuscript. Chris Friesen facilitated the exchange of specimens between the first two authors. Lyndi Garnett provided commentary on the identity of the Salvia species. Matt Buffington and Jerry Bowdrey provided useful information on Salvia gall wasp records in the US and United Kingdom. José Luis Nieves-Aldrey confirmed the identity of the Neaylax species.
This material is based upon work supported by the National Science Foundation under Grant Nos. DEB-1856626 and DEB-2338008. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. LFN was supported by additional awards from the Society of Systematic Biologists.
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Figs 1–5: Neaylax verbenacus (Nieves-Aldrey), adult female PSUC_FEM_81691 and galls in situ. 1 lateral habitus; 2 dorsal mesosoma; 3 gall in situ; 4 gall, cross section with developing cynipid larva; 5 host plant, flowering.
