Heritable beneficial bacterial endosymbionts have been crucial for the evolutionary success of numerous insects by enabling the exploitation of nutritionally limited food sources. Herein, we describe a previously unknown dual endosymbiosis in the psyllid genus Cacopsylla, consisting of the primary endosymbiont "Candidatus Carsonella ruddii" and a co-occurring Enterobacteriaceae bacterium for which we propose the name "Candidatus Psyllophila symbiotica." Its localization within the bacteriome and its small genome size confirm that Psyllophila is a co-primary endosymbiont widespread within the genus Cacopsylla. Despite its highly eroded genome, Psyllophila perfectly complements the tryptophan biosynthesis pathway that is incomplete in the co-occurring Carsonella. Moreover, the genome of Psyllophila is almost as small as Carsonella's, suggesting an ancient dual endosymbiosis that has now reached a precarious stage where any additional gene loss would make the system collapse. Hence, our results shed light on the dynamic interactions of psyllids and their endosymbionts over evolutionary time.

• Klíčová slova
• comparative genomics, endosymbionts, psyllids, symbiosis,
• MeSH
• Bacteria MeSH
• Enterobacteriaceae genetika   MeSH
• fylogeneze MeSH
• Hemiptera * genetika   MeSH
• symbióza genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Most sap-feeding insects maintain obligate relationships with endosymbiotic bacteria that provide their hosts with essential nutrients. However, knowledge about the dynamics of endosymbiont titers across seasons in natural host populations is scarce. Here, we used quantitative PCR to investigate the seasonal dynamics of the dual endosymbionts "Candidatus Carsonella ruddii" and "Ca. Psyllophila symbiotica" in a natural population of the pear psyllid Cacopsylla pyricola (Hemiptera: Psylloidea: Psyllidae). Psyllid individuals were collected across an entire year, covering both summer and overwintering generations. Immatures harboured the highest titers of both endosymbionts, while the lowest endosymbiont density was observed in males. The density of Carsonella remained high and relatively stable across the vegetative period of the pear trees, but significantly dropped during the non-vegetative period, overlapping with C. pyricola's reproductive diapause. In contrast, the titer of Psyllophila was consistently higher than Carsonella's and exhibited fluctuations throughout the sampling year, which might be related to host age. Despite a tightly integrated metabolic complementarity between Carsonella and Psyllophila, our findings highlight differences in their density dynamics throughout the year, that might be linked to their metabolic roles at different life stages of the host.

• MeSH
• Bacteria MeSH
• Hemiptera * mikrobiologie   MeSH
• lidé MeSH
• Pyrus * MeSH
• roční období MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Wolbachia is one of the most abundant intracellular symbionts of arthropods and has profound effects on host biology. Wolbachia transmission and host phenotypes often depend on its density within the host, which can be affected by multiple biotic and abiotic factors. However, very few studies measured Wolbachia density in natural host populations. Here, we describe Wolbachia in the pear psyllid Cacopsylla pyri from three populations in the Czech Republic. Using phylogenetic analyses based on wsp and multilocus sequence typing genes, we demonstrate that C. pyri harbours three new Wolbachia strains from supergroup B. A fourth Wolbachia strain from supergroup A was also detected in parasitised immatures of C. pyri, but likely came from a hymenopteran parasitoid. To obtain insights into natural Wolbachia infection dynamics, we quantified Wolbachia in psyllid individuals from the locality with the highest prevalence across an entire year, spanning several seasonal generations of the host. All tested females were infected and Wolbachia density remained stable across the entire period, suggesting a highly efficient vertical transmission and little influence from the environment and different host generations. In contrast, we observed a tendency towards reduced Wolbachia density in males which may suggest sex-related differences in Wolbachia-psyllid interactions.

• MeSH
• fylogeneze MeSH
• Hemiptera * genetika   MeSH
• Pyrus * MeSH
• roční období MeSH
• Wolbachia * genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH