Reproductive ecology affects invasion: Sirex noctilio as a case study

Reproductive ecology affects the population dynamics of insect species and their capacity to adapt to new environments. Consequently, reproductive ecology should influence the capacity of introduced insects to establish into new areas. With a century of recorded introductions throughout the Southern Hemisphere’s planted forests, Sirex noctilio is a great model species to understand the link between reproductive ecology and invasion. Understanding the reproductive aspects of the biology of the wasp, such as behaviour, sex determination or reproductive parasites can also open new doors towards the development of efficient monitoring and management strategies. The poster will present recent findings on the reproductive ecology of the wasp and will use this work to illustrate the need for a better understanding of reproductive biology in invasive insects. Some of this recent work demonstrated that after introduction in parts of South Africa, S. noctilio exhibited low levels of genetic diversity, leading to the production of diploid males and to a male-biased sex ratio. We also found that females exhibited low mating success and that mated females invested more in sons than in daughters, probably due to introduced populations not being adapted to the local environment. Further research focused on mating behaviour and demonstrated that size and age affect mating success in both sexes. Finally, an exploration into the genome of S. noctilio revealed the presence of pseudogenes horizontally transferred from the bacterial endosymbiont Wolbachia to S. noctilio, followed by a loss of the symbiosis.