How much does the host matter to the parasitoid? Distribution of Eurytoma (Hymenoptera, Chalcidoidea) species amongst two locally co-occurring gall-inducing hosts in the genus Diplolepis (Hymenoptera, Cynipidae)

Abstract

Gall wasps in the cynipid genus Diplolepis Geoffroy (Hymenoptera: Cynipidae) attack various species of native and introduced roses in Canada. Although gall forms are diverse, gall wasps are parasitised by highly concordant complexes of parasitoids and inquilines. Many species of gall wasps attack the same host plants and develop over the same periods in the season, suggesting that opportunistic parasitoids may be exploiting a range of hosts rather than specialising. We sampled larvae of Eurytoma Illiger (Hymenoptera: Cynipidae) from galls of D. variabilis (Bassett) and D. rosaefolii (Cockerell), gall inducers that develop fairly synchronously late in the growing season on leaves of Rosa woodsii Lindl. (Rosaceae) in the Okanagan Valley of central British Columbia, Canada. Galls were sampled at five different sites along a gradient from the north end of the valley to the Canada–United States border, a distance of 100 km. We extracted DNA, then amplified and sequenced the cytochrome b segment for each Eurytoma larva. We identified two well-supported clades that were differentiated by neither sampling location nor host. Instead, at least two species of Eurytoma, E. imminuta Bugbee and E. longavena Bugbee, exist at these localities, and both exploit at least two of the Diplolepis hosts found at these sites.

Species composition of the parasitoid genus Eurytoma (Hymenoptera: Eurytomidae) varies at a local scale in Diplolepis variabilis (Hymenoptera: Cynipidae) galls

“…The assemblage of arthropods present within galls is frequently described as static communities whose composition is essentially invariable at the level of the specific gall system (Askew 1980; Stone et al 2002; Shorthouse 2010). Recent work has improved our understanding of the complexities and variable patterns that emerge in these communities at local scales (Joseph et al 2011; Bannerman et al 2012; MacEwen et al 2020). For example, molecular approaches have demonstrated the presence of morphologically cryptic taxa co-existing within the guilds of gall-inducers, parasitoids, and inquilines present in gall component communities (Zhang et al 2014; Start 2019; MacEwen et al 2020; Ward et al 2020).…”

“…Recent work has improved our understanding of the complexities and variable patterns that emerge in these communities at local scales (Joseph et al 2011; Bannerman et al 2012; MacEwen et al 2020). For example, molecular approaches have demonstrated the presence of morphologically cryptic taxa co-existing within the guilds of gall-inducers, parasitoids, and inquilines present in gall component communities (Zhang et al 2014; Start 2019; MacEwen et al 2020; Ward et al 2020). Morphologically cryptic species are a likely source of undiscovered biodiversity present within a system (Jörger and Schrödl 2013; Struck et al 2018).…”

Delimiting the cryptic diversity and host preferences of Sycophila parasitoid wasps associated with oak galls using phylogenomic data

“…Assessing species richness and revealing axes of host specialization for gall parasitoids requires a well-resolved and stable parasitoid taxonomy, which in turn requires an integrative approach. Single or multi-locus approaches for taxon delimitation that use genes such as the mitochondrial loci COI and Cytb have been used extensively to understand gall community diversity (Ács et al, 2010;Davis et al, 2018;Forbes et al, 2016;Gil-Tapetado et al, 2021;Kaartinen et al, 2010;MacEwen et al, 2020;Nicholls et al, 2018;Nicholls et al, 2010;Sheikh et al, 2022;Smith-Freedman et al, 2019;Ward et al, 2020;Weinersmith et al, 2020;Zhang Y.M. et al, 2014;2019a), often in combination with morphological and/or ecological data.…”

“…Assessing species richness and revealing axes of host specialization for gall parasitoids requires a well‐resolved and stable parasitoid taxonomy, which in turn requires an integrative approach. Single‐ or multilocus approaches for taxon delimitation that use genes such as the mitochondrial loci COI and Cytb have been used extensively to understand gall community diversity (Ács et al, 2010; Davis et al, 2018; Forbes et al, 2016; Gil‐Tapetado et al, 2021; Kaartinen et al, 2010; MacEwen et al, 2020; Nicholls et al, 2010, 2018; Nicholls et al, 2018; Sheikh et al, 2022; Smith‐Freedman et al, 2019; Ward et al, 2020; Weinersmith et al, 2020; Zhang et al, 2014; Zhang, László, et al, 2019), often in combination with morphological and/or ecological data. However, results from one or a few genes can be limited in resolution, and single‐locus mitochondrial COI barcodes are known to be misleading due to confounding factors such as incomplete lineage sorting and introgression within both gall wasps and their associated parasitoids (Nicholls et al, 2012; Rokas et al, 2003; Zhang et al, 2021).…”

Delimiting the cryptic diversity and host preferences of Sycophila parasitoid wasps associated with oak galls using phylogenomic data

“…Assessing species richness and revealing axes of host specialization for gall parasitoids requires a well-resolved and stable parasitoid taxonomy, which in turn requires an integrative approach. Single or multi locus approaches for taxon delimitation that use one or more genes such as the mitochondrial loci COI and Cytb have been used extensively to understand gall community diversity (Ács et al, 2010;Davis et al, 2018;Forbes et al, 2016;Gil-Tapetado et al, 2021;Kaartinen et al, 2010;MacEwen et al, 2020;Nicholls et al, 2018;Nicholls et al, 2010;Sheikh et al, 2021;Smith-Freedman et al, 2019;Ward et al, 2020;Weinersmith et al, 2020;Zhang Y.M. et al, 2014;2019a), often in combination with morphological and/or ecological data.…”