Distinct virulence of the microsporidian parasite in honey bees competing habitat.

Abstract

In natural ecosystems, parasites often infect multiple host species, particularly when hosts share habitats, facilitating host-to-host transmission and altering traditional host-parasite coevolution dynamics. This study examines the microsporidian parasite Nosema ceranae in Eastern honey bees (Apis cerana) and Western honey bees (Apis mellifera), assessing its virulence and proliferation dynamics. Using inoculation experiments, we measured bee mortality and parasite spore loads to infer virulence and proliferation. Additionally, time-series transcriptome analysis of both bees and parasites provide insights into host-pathogen interactions. The results reveal that N. ceranae produces more spores with lower mortality in A. mellifera but causes higher mortality with lower spore production in A. cerana. The parasite also suppresses host gene expression, with stronger suppression observed in A. cerana. These findings suggest that N. ceranae is adapted for low virulence and high proliferation in A. mellifera but exhibits high virulence and limited proliferation in A. cerana. This study highlights the evolution of distinct trade-offs between virulence and proliferation in a multi-host system, offering valuable insights into parasite-host dynamics and their ecological implications.