Thermal tolerance in two Eucalyptus invasive insect pests and how this might affect biological control

Temperature is one of the main drivers in the establishment and success of biological control agents. Differences in thermal tolerance between insect pests and their biological control agents can contribute to insect herbivore outbreaks. The rise in global surface temperatures is contributing to greater variability in local climatic factors and is expected to disrupt the future biological control of insect pests. Thermal tolerance measurements of insects are used to understand their ability to establish and overwinter in new environments, identify climatic mismatches between insect pests and their biological control agents and to predict their potential distributions in their introduced ranges. We examined upper and lower lethal and critical thermal tolerance measures of Gonipterus sp. n. 2 and Leptocybe invasa, and their respective biological control agents, to gain insights into possible climatic mismatches between them and their biological control agents. Furthermore, to consider the impact of climate change on biological control programmes for these insect pests. Differences in upper and lower lethal thresholds between Gonipterus sp. n. 2 and Anaphes nitens indicated a climatic mismatch between Gonipterus sp. n. 2 and A. nitens. Critical and lethal thermal limits of L. invasa were within the thermal range of its biological control agents, Selitrichodes neseri and Quadrastichus neseri. The results of this study will facilitate the development of climate change prediction models and the establishment of climatically robust integrated pest management programmes for economically important forest insect pests.