Host tissue identification for cryptic hymenopteran parasitoids associated withSirex noctilio

Abstract

1 Establishing host-parasitoid relationships is challenging for cryptic insects feeding deep in the xylem tissue of trees. Sirex noctilio is a xylophagous feeder and recent invader of North America that co-occurs in pines (Pinus) with a native siricid (Sirex nigricornis) and a suite of shared hymenopteran parasitoids. This insect has a long history as a destructive pest in Southern Hemisphere pine plantations. 2 To establish explicit trophic linkages between native hymenopteran parasitoids and two species of woodwasp (Sirex) in North America, a polymerase chain reaction assay was developed to amplify mitochondrial DNA that was restriction digested with the aim of identifying species. The assay was used to identify species of Sirex from cadavers and gut contents from different parasitoid stages with the aim of establishing host-parasitoid relationships. 3 The host woodwasp species was identified successfully from parasitoid gut contents collected from larvae, pupae and adults. Across all parasitoid life stages, woodwasp host was identified in 52.9% of ibaliid parasitoids and 78.5% of rhyssine parasitoids. Host was successfully identified from 88.1% of associated siricid cadavers. 4 These results demonstrate the utility of molecular techniques to verify host-parasitoid associations that previously had only been inferred. Development of molecular tools is a rapid and crucial tool for establishing trophic linkages and is particularly useful in situations involving non-native species with cryptic lifestyles.

Beneath the bark: associations among Sirex noctilio development, bluestain fungi, and pine host species in North America

“…All logs (n = 583) were split within 3 months of the initial collection date. PCR assays were used to identify siricid tissue using methods described in Foelker et al (2016b). All live and dead siricid larvae and parasitoid gut contents were identified as S. noctilio.…”

Complex ecological relationships among an assemblage of indigenous hymenopteran parasitoids, the exotic European woodwasp (Sirex noctilio; Hymenoptera: Siricidae), and a native congener

“…This native parasitoid assemblage is composed of an egg/early instar parasitoid, four late instar rhyssine parasitoids, and a rhyssine cleptoparasitoid. All species have been directly linked to S. noctilio through both observational and molecular means (Foelker et al 2016). The study described here constitutes the most comprehensive evaluation of parasitism of S. noctilio in North America.…”

“…They have different fungal symbionts (but see Hajek et al (2013)), emergence phenologies (Ryan et al 2012), and attack trees in different stages of decline (Schiff et al 2012). Despite this, parasitoids appear to have readily adopted S. noctilio as a host (Long et al 2009; Eager et al 2011; Ryan et al 2012; Standley et al 2012; Foelker et al 2016).…”

Population level interactions between an invasive woodwasp, an invasive nematode and a community of native parasitoids

“…Four species of rhyssines (Ichneumonidae) parasitize later larval instars, and Pseudorhyssa nigricornis (also Ichneumonidae) is a kleptoparasitoid attacking the rhyssines (Foelker and Parry 2021) (Table 1). The biologies of these native parasitoid species are not well understood, although molecular analyses have shown that the rhyssines (analyzed as a group) and I. l. ensiger parasitize both S. nigricornis and S. noctilio (Foelker et al 2016b).…”