Interactions Between Endosymbionts Wolbachia and Rickettsia in the Spider Mite Tetranychus turkestani: Cooperation or Antagonism?

Abstract

Maternally inherited endosymbionts are widespread in arthropods, with multiple symbionts commonly co-existing within a single host, potentially competing for or sharing limited host resources and space. Wolbachia and Rickettsia, two maternally-inherited symbionts in arthropods, can co-infect hosts, yet research on their combined impacts on host reproduction and interaction remains scarce. Tetranychus turkestani (Acari: Tetranychidae) is an important agricultural pest mite, characterized by rapid reproduction, a short life cycle, and being difficult to control. Wolbachia and Rickettsia are two major endosymbiotic bacteria present in T. turkestani. This study used diverse parthenogenetic backcross and antibiotic screening to explore the reproductive effects of these two symbionts on T. turkestani. The results show that single Rickettsia infection induced male killing in the amphigenesis of T. turkestani, leading to arrhenotokous embryo death and fewer offspring. Single Wolbachia infection induced strong cytoplasmic incompatibility (CI). During dual infection, CI intensity decreased because Rickettsia's male-killing effect antagonized the Wolbachia-induced CI. Dual-infected mites had increased oviposition, lower mortality, a higher female-to-male ratio, and more offspring, thus enhancing T. turkestani's fitness. These findings will be helpful for understanding the nature of host-endosymbiont interactions and the potential for evolutionary conflicts, offering insights into their co-evolutionary relationship.