Is Host Selection by Mosquitoes Driving Vector Specificity of Parasites? A Review on the Avian Malaria Model

Rafael Gutiérrez-López,Vincent Bourret,Claire Loiseau

doi:10.3389/fevo.2020.569230

Abstract

Parasites and hosts are in a complex evolutionary arm race where host compatibility represents a key obstacle for successful infections. The degree of parasite specialization on a host varies along a continuum: on one end, extreme specialist parasites may be restricted to a single host species, and on the other, generalist parasites are able to infect a diverse set of hosts. Multiple intrinsic factors associated to the host, such as their immune system and physiological condition, can contribute to the evolution of host specificity of parasites and have been well-studied and documented in vertebrates. In contrast, vector specificity of parasites has been largely overlooked, especially in natural conditions. While a few studies suggested that insect vectors do not play an important role in shaping the parasite community structure since they may feed widely from the bird community, current studies have demonstrated the importance of vector feeding behaviour on transmission dynamics for several vector-borne pathogens. Here, we provide a review on the specialization of avian Plasmodium in vectors, emphasizing the necessity to study simultaneously the three players to further understand how host choice by the vectors might influence the distribution of parasites in the wild. In addition, we suggest specific research directions making use of both empirical data gathered in the field and controlled experiments on vector host‐feeding preferences

Highlights

The degree of parasite specialization for a host varies along a continuum: on one end, extreme specialist parasites may be restricted to a single host species, and on the other, generalist parasites are able to infect a diverse set of hosts, with a large diversity of intermediate states (Vázquez et al, 2005; Poulin, 2007; Hellgren et al, 2009; Mccoy et al, 2013)
For parasites such as avian Plasmodium, with a complex life cycle that involves two hosts, one vertebrate and one insect, additional parameters linked to the insect, such as its feeding behavior or immune system, may influence parasite specialization (Billingsley and Sinden, 1997; GutiérrezLópez et al, 2020)
Research projects based on a global approach to host-parasite relationships that integrates the pivotal role of vectors in avian malaria transmission are still very rare, but essential to understand the evolutionary strategies of parasites

Summary

INTRODUCTION

The degree of parasite specialization for a host varies along a continuum: on one end, extreme specialist parasites may be restricted to a single host species, and on the other, generalist parasites are able to infect a diverse set of hosts, with a large diversity of intermediate states (Vázquez et al, 2005; Poulin, 2007; Hellgren et al, 2009; Mccoy et al, 2013). Researchers performed experimental work to identify competent vector species for different avian Plasmodium lineages by studying sporogonic development in salivary glands or saliva (Valkiunas, 2005; Kazlauskiene et al, 2013; Palinauskas et al, 2016; Carlson et al, 2018; Gutiérrez-López et al, 2020). Among many lines of research that could improve our understanding of vector specificity, future projects should focus on (i) questioning the parasite transmission capacity of mammophilic mosquitoes since, so far, Plasmodium lineages have been found in head/thorax only and not in salivary glands, (ii) testing the vector competence of mosquitoes that share the same habitat as Cx. pipiens but are present in lower abundance, (iii) determining if the infection status of the mosquitoes influences their host selection, using a wide range of mammals and bird species, or, (iv) evaluating if lineages with different host specialization strategies (specialists vs generalists) are transmitted by mosquitoes

CONCLUSION

Findings

DATA AVAILABILITY STATEMENT