Parasite prevalence corresponds to host life history in a diverse assemblage of afrotropical birds and haemosporidian parasites

Abstract

Avian host life history traits have been hypothesized to predict rates of infection by haemosporidian parasites. Using molecular techniques, we tested this hypothesis for parasites from three haemosporidian genera (Plasmodium, Haemoproteus, and Leucocytozoon) collected from a diverse sampling of birds in northern Malawi. We found that host life history traits were significantly associated with parasitism rates by all three parasite genera. Nest type and nest location predicted infection probability for all three parasite genera, whereas flocking behavior is an important predictor of Plasmodium and Haemoproteus infection and habitat is an important predictor of Leucocytozoon infection. Parasite prevalence was 79.1% across all individuals sampled, higher than that reported for comparable studies from any other region of the world. Parasite diversity was also exceptionally high, with 248 parasite cytochrome b lineages identified from 152 host species. A large proportion of Plasmodium, Haemoproteus, and Leucocytozoon parasite DNA sequences identified in this study represent new, previously undocumented lineages (n = 201; 81% of total identified) based on BLAST queries against the avian malaria database, MalAvi.

Fig 1. Map of sampling locations in northern Malawi.

Vwaza Marsh Wildlife Reserve, red; Nyika National Park, orange. Image credit: USGS National Map Viewer.

Fig 2. Predicted (least-squares mean) probabilities of parasitism and their 95% confidence intervals.

Expected rates of parasitism illustrated according to (a—c) host nest type, (d—f) host nest location, (g—h) host flocking behavior, and (i) habitat. For all panels, Plasmodium is represented by a black diamond and the letter “P”, Haemoproteus is represented by a black square and the letter “H”, and Leucocytozoon is represented by a black circle and the letter “L”. Number of individuals and species comprising each trait are listed below their respective traits (number of individuals above, number of species below in parentheses). Note that the parasitism rate of zero has been plotted for the aquatic habitat without confidence intervals; because the four individual aquatic-habitat birds sampled lack Leucocytozoon infections and therefore could not be used in the statistical analysis (as noted in the Methods section) Thus no measure of statistical confidence is associated with this aquatic habitat plotted point.