Plant-mediated interspecific horizontal transmission of an intracellular symbiont in insects

Abstract

Intracellular reproductive manipulators, such as Candidatus Cardinium and Wolbachia are vertically transmitted to progeny but rarely show co-speciation with the host. In sap-feeding insects, plant tissues have been proposed as alternative horizontal routes of interspecific transmission, but experimental evidence is limited. Here we report results from experiments that show that Cardinium is horizontally transmitted between different phloem sap-feeding insect species through plants. Quantitative PCR and in situ hybridization experiments indicated that the leafhopper Scaphoideus titanus releases Cardinium from its salivary glands during feeding on both artificial media and grapevine leaves. Successional time-course feeding experiments with S. titanus initially fed sugar solutions or small areas of grapevine leaves followed by feeding by the phytoplasma vector Macrosteles quadripunctulatus or the grapevine feeder Empoasca vitis revealed that the symbionts were transmitted to both species. Explaining interspecific horizontal transmission through plants improves our understanding of how symbionts spread, their lifestyle and the symbiont-host intermixed evolutionary pattern.

Phylogeography of Diaphorina citri (Hemiptera: Liviidae) and its primary endosymbiont, ‘Candidatus Carsonella ruddii’: an evolutionary approach to host–endosymbiont interaction

“…Studies of C. ruddii might help to clarify the genealogy and migration history of their hosts, because this P‐endosymbiont is present in 100% of hosts (data in this study) and is strictly maternally inherited . Some secondary endosymbionts are maternally inherited, but can also undergo horizontal transmission between hosts, leading to incongruent host–symbiont phylogenies . Although, more diversity and structure were observed in host mtDNA at the fine scale in some cases (e.g.…”

Genetic variability, community structure, and horizontal transfer of endosymbionts among three Asia II‐Bemisia tabaci mitotypes in Pakistan

“…A comparison of the phylogenetic tree of the secondary endosymbiont Arsenophonus (Figure ) with that of its B. tabaci host tree (Figure ) showed a pattern reminiscent of horizontal transmission, in which heritable facultative bacterial endosymbionts have been transferred either between related or divergent insects (Gonella et al, ; Gueguen et al, ; Mansoor et al, ; Oliver, Degnan, Burke, & Moran, ; Thao et al, ; Tsuchida, ; Weiss et al, ). Such pattern is consistent with the niche overlap observed for the three mitotypes in the Lahore collection sites (Figure ).…”

Fitness costs of infection with Serratia symbiotica are associated with greater susceptibility to insecticides in the pea aphid Acyrthosiphon pisum

“…Although the secondary symbionts of insects are maternally transmitted with high fidelity, they are occasionally transferred horizontally, allowing them to spread within and between species . Potential transmission routes include shared host plants or parasitoids, resulting in the direct acquisition of novel ecological traits …”