Data from: Infection with Haemoproteus iwa affects vector movement in a hippoboscid fly – frigatebird system

Haemosporidian parasites, which require both a vertebrate and invertebrate host, are most commonly studied in the life stages occurring in the vertebrate. However, aspects of the vector's behavior and biology can have profound effects on the parasite dynamics. Here we explore the effects of a haemosporidian parasite, Haemoproteusiwa, on a hippoboscid fly vector, Olfersiaspinifera. Olfersiaspinifera is an obligate ectoparasite of the great frigatebird, Fregata minor, living among bird feathers for all of its adult life. This study examines the movements of O. spiniferabetween great frigatebird hosts. Movement, or host-switching, was inferred by identifying host (frigatebird) microsatellite genotypesfrom fly bloodmeals that did not match the host from which the fly was collected. Such host-switches were analyzed using a logistic regression model, and the best-fit model included the H. iwa infection status of the fly and the bird host sex. Uninfected flies are more likely to have a bird genotype in their blood meal that was different from their current host's genotype (i.e., to have switched hosts) than infected flies. Flies collected from female birds were more likely to have switched hosts than those collected on males. Reduced movement of infected flies suggests that there may be a cost of parasitism for the fly. The effect of host sex is likely driven by differences in the sex ratio of bird hosts available to moving flies.血孢子虫（Haemosporidian）需要脊椎动物与无脊椎动物两类宿主，现有研究多聚焦于其在脊椎动物体内的生活阶段。然而，媒介昆虫的行为与生物学特性，可对寄生虫的种群动态产生深远影响。本研究探讨了血簇虫（Haemoproteus iwa）对其虱蝇科媒介*Olfersia spinifera*的影响。*Olfersia spinifera*是大军舰鸟（Fregata minor）的专性外寄生生物，成虫阶段全程栖息于宿主鸟类的羽毛之中。 本研究考察了*O. spinifera*在不同大军舰鸟宿主间的移动行为。研究通过比对蝇类血餐中提取的宿主（大军舰鸟）微卫星基因型与采集该蝇类的原宿主基因型，推断其是否发生了宿主转换（即移动行为）。研究采用逻辑回归模型对这类宿主转换事件进行分析，最优拟合模型纳入了蝇类的*H. iwa*感染状态与鸟类宿主的性别两个变量。结果显示，未感染的蝇类，其血餐中的鸟类基因型与当前宿主基因型不符（即发生宿主转换）的概率，显著高于已感染蝇类；从雌性大军舰鸟宿主采集的蝇类，发生宿主转换的概率也显著高于从雄性宿主采集的个体。感染蝇类的移动能力下降，提示寄生作用可能对蝇类带来了适合度代价。宿主性别所产生的上述影响，可能源于移动蝇类可接触到的鸟类宿主的性比差异。