Probing the role of propagule pressure, stochasticity, and Allee effects on invasion success using experimental introductions of a biological control agent

To study the role of population size and how it relatesto the Allee effect in the early stage of establishment, the leaf beetle Neolema ogloblini (Chrysomelidae) a biocontrol agent released against Tradescantia fluminensis (Commelinaceae) in New Zealand, was used as a model species. By manipulating initial population size over replicated releases, we examined how population size influences: (i) the probability of establishment and (ii) the per capita population growth of established populations.