Abstract / Summary
Abstract Island ecosystems are highly vulnerable to invasive vectors and pathogens, yet many lack baseline information needed to detect emerging disease systems. Rangitāhua, approximately 1000 km northeast of mainland Aotearoa New Zealand, has had limited prior mosquito monitoring and no assessment of avian parasites. We conducted an integrated field and molecular study to identify mosquito species, assess haemosporidian parasite prevalence in mosquitoes and birds, and evaluate mosquito feeding ecology. We report the first record of the introduced mosquito Culex quinquefasciatus , consistent with recent establishment, alongside the endemic Culex pervigilans . Four Plasmodium lineages were detected across birds and mosquitoes. Three were closest to P. elongatum , P. vaughani and P. relictum but did not exactly match sequences in public databases, while P. matutinum exactly matched the LNN1 lineage. Plasmodium prevalence was high in tūī ( Prosthemadera novaeseelandiae ) and introduced passerines ( Turdus merula and T. philomelos ), whereas no haemosporidian infections were detected in kākāriki ( Cyanoramphus novaezelandiae ), although sample sizes were limited. Among female mosquitoes, parasite detection was greater in the native Cx. pervigilans (41%) than in Cx. quinquefasciatus (4%). Detection of Plasmodium in both birds and mosquitoes indicates active local transmission, although marked heterogeneity among bird and mosquito species suggests uneven transmission dynamics. DNA metabarcoding indicated that mosquitoes utilised a broad range of native and exotic plant taxa, which may facilitate their persistence in a resource-limited island environment. This study demonstrates the value of integrated ecological and molecular approaches for understanding invasion processes and detecting emerging vector–pathogen interactions on remote island ecosystems.