Effects Of Endosymbionts Wolbachia And Cardinium On The Reproduction Of Tetranychus Truncatus Ehara And Tetranychus Piercei Mcgregor From China

Both the Tetranychus truncatus Ehara and Tetranychus piercei McGregor, which belong to Arachnida, Acari, Acariformes, Tetranychidae, Tetranychus, are very important mite pests. Wolbachia and Cardinium are maternally inherited intracellular bacteria that infect a wide range of arthropods, which could manipulate their host’s reproductive mode and thereby enhance their own spread. Cytoplasmic incompatibility (CI) is one of the important manipulations. Many factors, including host genotype, bacterial stains, bacterial density and sperm cyst infection, have been proposed to affect expression of CI. In this study, we investigated the effect of Wolbachia and/or Cardinium on the reproduction and fitness of Chinese populations of Tetranychus truncates and Tetranychus piercei Mcgrvgor, and identified factors that affect Wolbachia-induced and Cardinium-induced CI. We also revealed characteristic localization patterns of Wolbachia and Cardinium in the female, which were suggestive of the route and mechanism of their vertical transmission. Our results probably indicated migrating Wolbachia and Cardinium with trophic flow from nurse cells, midgut and oviduct to the oocytes.Wolbachia and Cardinium have been found coinfecting in the same host apecies. Both Wolbachia and Cardinium bacteria have been studied to cause cytoplasmic incompatibility, but little is known about their interaction. In this study, we investigated the effects of both Wolbachia and Cardinium, and their interactions, in the Gansu (GS), Guangdong (GD) and Yunnan (YN) populations. GS population is Tetranychus truncatus Ehara, and GD population and YN population are Tetranychus piercei McGregor. In GS and GN populations, singly Wolbachia-infected males induced weak CI, and Singly Cardinium-infected male and doubly infected males induced strong CI. In the YN population, the level of incompatibility induced by doubly infected was higher than that by singly Cardinium-infected and singly Wolbachia-infected males. Our results intimated that Wolbachia promoted the strength of Cardinium-induced CI in the doubly infected mites. We did not find evidence that Cardinium was able to modify or rescue Wolbachia-induced CI. In our experiments, GD population and YN population are Tetranychus piercei Mcgrvgor, GS population is Tetranychus truncates. GS and GD population infected with wCon, and YN population infected with wOri. Cardinium of this three populations infected were very similar, similarity is97%-99%. In GS and GD populations, the level of CI was induced by doubly infected and singly infected males, was differently. It indicated that the host genetic background may affect the CI expression. In YN population, the wOri strain may promote CI which was induced by doubly infected males.To investigate the effect of Wolbachia and Cardinium densities on expression of CI, the copy numbers of the wsp gene and16S rDNA gene were measured using quantitative PCR. Adult males of12stages (1,3,5,7,9,11,13days old) in the GD and YN populations were examined.In the GD population, the interaction between Wolbachia and Cardinium was cooperative and competitive among the13days after adult emergence. In the YN populations, the infection density of Cardinium was promoted by Wolbachia in the doubly infected males after5days old. It may be the reason that the CI degree of doubly infected lines was stronger than that of singly Cardinium-infected lines.We examine the relationship between the levels of CI in singly infected and doubly infected mles and the infection of during spermatogenesis. Doubly infected Wolbachia and Cardinium, singly Wolbachia-infected and singly Cardinium-infected mites (male and female) of1-day-old were collected separately. Adult mites were prepared and treated by Fluorescence in situ hybridization (FISH). Our results showed that a positive correlation between CI levels and infection status of the developing sperm. We also revealed characteristic localization patterns of Wolbachia and Cardinium in the female, which were suggestive of the route and mechanism of their vertical transmission. Firstly, Wolbachia and Cardinium with trophic flow transferred from nurse cells to oocyte before vitellogenesis. Secondly, during the vitellogenesis, Wolbachia and Cardinium moved from midgut and hemolymph with trophic flow. Thirdly, in the process of eggshell formation, in the cavity and the oviduct additional cement and wax layers are added to the shell, Wolbachia and Cardinium moved from cavity and oviduct to the egg.