Diet affects the growth and behavior of Argiope bruennichi spiders and correlates with the species richness of their vertically and horizontally transmitted tissue-resident bacteria

The ability to spread and build quality webs is crucial to spider survival. These abilities may differ in response to dietary adjustments and changes in assemblages of tissue-resident bacteria, including vertically transmitted endosymbiotic taxa, particularly when expanding outside the native ranges. We measured the physical and behavioral parameters of the invasive wasp spider Argiope bruennichi subjected to four types of diets, including protein-rich and lipid-rich diets. We used 16S rDNA sequencing to evaluate vertically and horizontally transmitted tissue-resident bacteria, including endosymbionts, in the cephalothorax and legs of the tested spiders. The diet composition affected the body weight and carapace length as well as the locomotor parameters but not the orb-weaving abilities. Dietary treatments led to changes in the diversity and operational taxonomic unit (OTU) richness of facultative and obligate tissue endosymbionts, with Wolbachia and Rickettsia having higher relative abundance in spiders fed a lipid-rich diet. The higher OTU richness of facultative and obligate endosymbionts was associated with better locomotor performance. The other tissue-resident microbes were dominated by Firmicutes
the dominance and diversity of tissue-resident microbiomes also differed among spiders treated with different diets. The highest alpha diversity of tissue-resident microbes was present in spiders fed the standard diet, whereas all other diets led to a decrease in alpha diversity and various changes at the level of individual genera and OTUs. In conclusion, the tissues of Argiope bruennichi host tremendously diverse assemblages of bacteria, including obligate or facultative endosymbionts, which are sensitive to differences in diet composition and affect the locomotion of their hosts.