Parasitoids are central to classical biological control, yet predicting their long‐term effectiveness post release remains challenging. In Aotearoa New Zealand, three Microctonus (Hymenoptera: Braconidae) species have been used against pest weevils, but key aspects of their biology remain poorly understood. This is evident in postrelease decline of M. hyperodae efficacy and geographically variable nontarget impacts among M. aethiopoides strains. Such cases highlight knowledge gaps in host‐searching behaviour, reproductive mode, adaptability to environmental conditions, and microbiome composition within parasitoids and hosts. We review studies, mainly on Hymenopteran parasitoids, focusing on key adaptive traits important in biocontrol: reproductive mode, olfaction, thermal tolerance, and symbiont interactions. Synthesising findings from host specificity, behavioural, and molecular analyses, we identify broader patterns and key gaps. While molecular research on Microctonus is limited, evidence from other systems shows trait‐specific adaptive responses, with variation in olfactory sensitivity, reproductive strategies, and the microbiome interactions influencing host use success and potentially persistence. While field‐level efficacy is often assessed, species‐specific evaluation of life history traits under relevant environmental conditions is essential, followed by genomic and transcriptomic studies to reveal the molecular basis of adaptation. Integrating behavioural, molecular, microbiome, and ecological insights will be essential for optimising parasitoid releases and ensuring long‐term biocontrol success in New Zealand.
Hussain et al. (2026) studied this question.