Bacterial endosymbionts identified from leafhopper (Hemiptera: Cicadellidae) vectors of phytoplasmas

Authors: Cooper, William - Rodney; Walker, William; Angelella, Gina; Swisher Grimm, Kylie; FOUTZ, JILLIAN - Washington State University; HARPER, SCOTT - Washington State University; NOTTINGHAM, LOUIS - Washington State University; NORTHFIELD, T - Washington State University; WOHLEB, CARRIE - Washington State University; STAUSBAUGH, CARL - US Department Of Agriculture (USDA)

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2023
Publication Date: 3/4/2023
Citation: Cooper, W.R., Walker III, W.B., Angelella, G.M., Swisher Grimm, K.D., Foutz, J.J., Harper, S.J., Nottingham, L.B., Northfield, T.D., Wohleb, C.H., Stausbaugh, C.A. 2023. Bacterial endosymbionts identified from leafhopper (Hemiptera: Cicadellidae) vectors of phytoplasmas. Environmental Entomology. 52(2):243-353. https://doi.org/10.1093/ee/nvad015.
DOI: https://doi.org/10.1093/ee/nvad015

Interpretive Summary: Many insects harbor beneficial bacteria called symbionts that provide them with nutrition, or with protection from natural enemies, insecticides, and plant defenses. Researchers from the USDA-ARS in Wapato, WA and Kimberly, ID, and from Washington State University, identified symbionts from leafhopper vectors of plant diseases caused by phytoplasma including cherry X-disease (aka, little cherry disease) and potato purple top disease (aka, BLTVA). They discovered several symbionts from that were previously unknown and that may be beneficial to the vectors. They also provided evidence that the symbiont, Wolbachia, may increase the number of beet leafhoppers that carry the potato purple top phytoplasma. Results of this study provide a foundation to conduct more research on leafhopper symbionts and how they influence biology and management of these important insect vectors.

Technical Abstract: Insects often harbor bacterial endosymbionts that provide them with nutritional benefit or with protection against natural enemies, plant defenses, insecticides, and abiotic stresses. Certain endosymbionts may also alter acquisition and transmission of plant pathogens by insect vectors. We identified bacterial endosymbionts from four leafhopper vectors (Hemiptera: Cicadellidae) of ‘Candidatus Phytoplasma’ species by direct sequencing 16S rDNA and confirmed endosymbiont presence and identity by species-specific conventional PCR. We examined three vectors of Ca. Phytoplasma pruni, causal agent of cherry X-disease [Colladonus geminatus (Van Duzee), Colladonus montanus reductus (Van Duzee), Euscelidius variegatus (Kirschbaum)] – and a vector of Ca. Phytoplasma trifolii, the causal agent of potato purple top disease [Circulifer tenellus (Baker)]. Direct sequencing of 16S identified the two obligate endosymbionts of leafhoppers, ‘Ca. Sulcia’ and ‘Ca. Nasuia’, which are known to produce essential amino acids lacking in the leafhoppers’ phloem sap diet. About 57% of C. geminatus also harbored endosymbiotic Rickettsia. We identified ‘Ca. Yamatotoia cicadellidicola’ in Euscelidius variegatus, providing just the second host record for this endosymbiont. Circulifer tenellus harbored the facultative endosymbiont Wolbachia, although the average infection rate was only 13% and all males were Wolbachia-uninfected. A significantly greater percentage of Wolbachia-infected Ci. tenellus adults than uninfected adults carried Ca. P. trifolii, suggesting that Wolbachia may increase this insect’s ability to tolerate or acquire this pathogen. Results of our study provide a foundation for continued work on interactions between leafhoppers, bacterial endosymbionts, and phytoplasma.