Samantha Page

Date of Award


Document Type



Environmental and Forest Biology

Thesis Advisor

Christopher M. Whipps


hymenopteran parasitoids, xylophagus insects, cryptic species, invasive species, molecular ecology


The European woodwasp, Sirex noctilio, is a wood-boring insect native to Eurasia and North Africa, which was accidentally introduced across the Southern Hemisphere where it caused extensive economic damage to conifer plantations. Discovered ten years ago in North America, S. noctilio competes directly with Sirex nigricornis, a native congener, through shared resources in host trees. The two species also share a suite of six parasitoids, which utilize both native and non-native species of woodwasps as hosts. To study these interactions, it is common practice to fell trees and split logs from which siricid larvae and their parasitoids are collected. It is exceedingly difficult to identify larval species due to their indistinct morphology. The objectives of this study were to: 1) differentiate between the native S. nigricornis and the non-native S. noctilio using PCR assays and 2) determine if such assays can be used to identify host species from a parasitoid’s gut contents. DNA was extracted from 206 siricid larvae and 202 were identifiable as S. noctilio (154, 73%) or S. nigricornis (48, 23%) using PCR, illustrating the applicability of this technique to differentiate among Sirex species. Identification of species from DNA extracted from host cadavers associated with parasitoid larvae was also successful (17 of 21, 81%). However, identification of species from DNA extracted from gut contents of parasitoids was also successful (12 of 35, 34%). Being able to successfully identify trophic linkages associated with non-native species is important to understand how they will invade an area and their ecological impacts.