As her thesis title states, Amy's project investigated the “Sex determination and symbiont transmission in the Sirex-Amylostereum mutualism”.  The literature review of the thesis laid a foundation for this by synthesizing the literature on the theoretical expectations and experimental evidence of factors that stabilize and destabilize mutualisms. Both mating and transmission (in how it affects specificity or continuity of symbionts between generations) are important in this regard. 

For her experimental chapters she worked on collections from two distinct regions. The first was a collection of Sirex noctilio and S. nigricornis and their associated Amylostereum areolatum and A. chailletii symbionts from Canada. She showed that these symbionts are exchanged between these Siricids, in contrast to the expectation of strict vertical transmission and specificity. The quality and novelty of the work, and its implications for control and ecology of Siricids in native areas, earned her a paper in the journal Biology Letters. 

The second and third research chapters of Amy’s MSc focused on South African populations of S. noctilio. For these she considered various factors that could affect the skewed sex ratio in the eastern part of South Africa. The work shows that a complex combination of genetic, behavioral and environmental factors interact to influence these population dynamics. 

Through this thesis Amy made an exceptional contribution to the knowledge in the field. As one of the examiners said: “I congratulate the candidate… on a well-designed and thorough study which has gone a long way towards improving our understanding of Sirex as an important invasive pest, and on the evolution and specificity of mutualisms in nature.” 

We congratulate Amy and wish her well for her PhD at Auburn University in the USA. 


Bernard Slippers, Jaco Greeff, Brett Hurley, Jeff Garnas, Mike Wingfield