Acquisition and transmission of lethal bronzing phytoplasma by Haplaxius crudus

Lethal Bronzing (LB) is a fatal palm disease caused by the phytoplasma ‘Candidatus Phytoplasma aculeata’. This disease causes significant economic losses in palm industries and landscapes. The American palm cixiid, Haplaxius crudus, was recently identified as the vector of the phytoplasma. However, the knowledge about LB phytoplasma transmission is limited due to the lack of a method to generate phytoplasma-infected insects in the laboratory. In this study, the acquisition and transmission of the LB phytoplasma by H. crudus were investigated. Successful acquisitions of the phytoplasma by H. crudus were observed at two days of the acquisition access period on LB-infected palm spear leaves. Analyses revealed increased phytoplasma infection rates of H. crudus as the longer acquisition access periods and latent periods were given. A significantly higher phytoplasma infection rate was shown after various acquisition access periods and latent periods than the infection rate of the field-collected H. crudus population. Transmission of the phytoplasma from LB-infected spear leaves to sucrose media by H. crudus was also observed using digital PCR assays. These results further support the vector status of H. crudus and offer valuable information to understand LB phytoplasma transmission. Additionally, these results opened the door to future LB phytoplasma-vector study by providing a way to generate vectors with high phytoplasma infection rates in the laboratory setting.