<b>Parthenogenetic Haemaphysalis longicornis </b><b>triploid genome</b>

Here we assembled a triploid chromosome-level genome of the parthenogenetic H. longicornis, and found that it originated from autopolyploid events rather than interspecific hybridization. We identified a set of functional genes that enable parthenogenetic ticks to complete embryogenesis without fertilization. Infection experiments with Rickettsia heilongjiangensis and severe fever with thrombocytopenia syndrome virus revealed that both pathogens proliferated faster with higher loads in parthenogenetic ticks compared to bisexual females. Contrary to the traditional belief that deleterious mutations accumulate in parthenogenetic populations, we found that deleterious mutations were actually fewer in parthenogenetic populations compared to bisexual ones. Ecological niche modeling predicted a wider potential global distribution for the parthenogenetic. This study provides the biological basis for the rapid expansion and enhanced vector competence of the parthenogenetic H. longicornis, highlighting its global risk for pathogen transmission.