Host selection and parasite infection in Aedes taeniorhynchus, endemic disease vector in the Galapagos Islands

摘要

Host selection in blood-sucking arthropods has important evolutionary and ecological implications for the transmission dynamics, distribution and host-specificity of the parasites they transmit. The black salt-marsh mosquito (Aedes taeniorhynchus Wiedemann) is distributed throughout tropical to temperate coastal zones in the Americas, and continental populations are primarily mammalphilic. It is the only indigenous mosquito in the Galapagos Islands, having colonised the archipelago around 200,000 years ago, potentially adapting its host selection, and in the process, altering the dynamics of vector mediated pathogen interactions in the archipelago. Here, we use blood-meal analysis and PCR-based parasite screening approach to determine the blood-feeding patterns of A taeniorhynchus in the Galapagos Islands and identify potential parasite transmission with which this mosquito could be involved. Our results show that A taeniorhynchus feeds equally on mammals and reptiles, and only one avian sample wasobserved in 190 successful PCR amplifications from blood meals. However, we detected endemic filarial worms and Haemoproteus parasites known to infect various Galapagos bird species in mosquito thoraces, suggesting that feeding on birds must occur at low frequency, and that A. taeniorhynchus may play a role in maintaining some avian vector-borne pathogens, although more work is needed to explore this possibility. We also isolated three different DNA sequences corresponding to hemogregarine parasites ofthe genus Hepatozoon from mosquito and iguana blood samples, suggesting that more than one species of Hepatozoon parasites are present in Galapagos. Phylogenetic analysis of Hepatozoon 18sRNA sequences indicates that A taeniorhynchus may have facilitated a recent breakdown in host-species association of formerly isolated Hepatozoon spp. infecting the reptile populations in the Galapagos Islands.