Recent advances in vector studies of avian haemosporidian parasites

Abstract

Many recent studies addressed morphological and molecular characterization, distribution, genetic diversity and evolutionary relationships of avian haemosporidian parasites (Haemosporida). However, the information about relationships between bird haemosporidians and their vectors remains fragmentary and scarce. Experimental studies on this subject are few. Recent advances in vector research of avian haemosporidians (Haemosporida) have been briefly reviewed in regard to the experimental studies, which have been carried out at the Nature Research Centre, Vilnius, during the last five years, with particular attention to widespread species of Plasmodium and Haemoproteus parasites. New information about vectors of avian malaria parasites and haemoproteids is provided and discussed. We point out high virulence of widespread Haemoproteus species for bloodsucking insects of the Culicidae and Ceratopogonidae, and call for additional studies on this subject. Due to widespread abortive sporogonic development in bloodsucking insects, Polymerase Chain Reaction (PCR)-based diagnostics should be carefully used in vector research of haemosporidians because it detects parasites in blood-sucking insects for several weeks after initial infection, but does not distinguish abortive parasite development. That questions vector studies, which are based solely on PCR-based tools. Demonstration of infective sporozoites in insects is essential for definitively demonstrating the insects are vectors. Because of the complicated life cycles of haemosporidians, microscopic approaches and experimental research remain essential and should be applied in parallel with PCRbased detection tools in vector studies, particularly in wildlife.