Press release November 18th, 2025

What is the key message of your study – in one sentence?

We found that the reed glasswing cicada, which has emerged as a new and significant pest in agriculture, harbours an unexpectedly wide range of microorganisms in various organs, including not only transmitted plant-pathogenic bacteria but also symbiotic microbes that probably play a role in its rapid adaptation to new host plants.

What were the key questions you pursued in the study – and what previous research findings, observations or gaps in research inspired you to do so?

As part of a collaboration between the Association of Hessian-Palatinate Sugar Beet Growers (Rathenaustraße 10, 67547 Worms, Germany) and the Max Planck Institute for Chemical Ecology in Jena, monitoring from 2017 to 2020 revealed that the reed glasswing cicada (Pentastiridius leporinus), which has been identified as a carrier of bacterial yellowing disease in sugar beet and is spreading in Hesse, Rhineland-Palatinate, Baden-Württemberg and Bavaria (Behrmann et al. 2021). In addition to the γ-proteobacterium Candidatus Arsenophonus phytopathogenicus (CAP), it also transmits the Stolbur phytoplasma Candidatus Phytoplasma solani (CPS), which causes the disease complexes ‘Syndrome des basses richesses’ (low sugar content syndrome, SBR) and Stolbur. This leads to a reduction in sugar content and ‘rubber beets’. This is accompanied by impaired storage and processing capabilities. Against this background, we have established a laboratory culture of the reed glasswing cicada and researched its biology (Behrmann et al. 2022). We have also discovered that this insect pest can use potatoes as a host plant and transmit its bacterial pathogens to them (Behrmann et al. 2023, Rinklef et al. 2024). As part of another research project, we are developing PCR-based methods for monitoring the spread of these plant pathogens. The rapid expansion of the host plant spectrum inspired us to investigate the possible causes.

Why is the reed glasswing cicada Pentastiridius leporinus a particularly exciting subject for research?

In a relatively short period of time, the native reed glasswing cicada has evolved from an endangered species into a rapidly spreading pest that transmits pathogens to an increasing number of crops (sugar beet, winter wheat, potatoes, onions, carrots, etc.), causing growing economic damage to agriculture. How this pest is able to adapt to the different defence mechanisms of its host plants is unknown. This insect is therefore particularly well suited for studying mechanisms that enable an expansion of the ecological niche in evolution. Furthermore, this pest is suitable as a model for the development of innovative and environmentally friendly control options.

In a nutshell: What are the most important findings of your study – in a few simple sentences?

In addition to the known plant pathogens Candidatus Arsenophonus phytopathogenicus and Candidatus Phytoplasma solani, we identified five other bacterial species (belonging to the genera Purcelliella, Karelsulcia, Vidania, Rickettsia and Wolbachia) in various organs of the reed glasswing cicada, which probably enable the cicada to feed on plant sap as symbionts. The genomes of both the plant pathogens and all symbionts were sequenced and their distribution in the body was localised.

Were there any results that really surprised you – such as an unexpected type of bacteria, an unusual location or a surprising variety of microbes?

We were amazed to find Wolbachia bacteria in the cells and Rickettsia bacteria even in the cell nucleus of tissues in the cicada.

How could the cicada's ability to switch from reed grass to sugar beet and potatoes be related to its microbial flora?

Many insects that feed exclusively on plant sap, such as aphids and cicadas, harbour symbiotic microorganisms in their bodies that provide vital substances such as vitamins. In the genomes of the microbial flora, we found genetic signatures that suggest that they can produce ten essential amino acids and B vitamins. In the genomes of plant pathogens, we have found various virulence factors that can contribute to the development of disease symptoms in infected plants. The transmitted plant pathogens cause visible disease symptoms and weaken the crops against vector insects.

What does it mean that CAP occurs in many tissues, while CPS is only found in the salivary glands – and how could this influence the transmission of plant diseases?

Only the microbes that occur in the salivary gland can be transmitted with the saliva to the respective host plant and from there via its plant sap to other individuals (horizontally). CAP, on the other hand, can also be transmitted to the next generation (vertically) with the eggs. In the case of obligate symbionts, it can be assumed that transmission to the next generation is exclusively vertical.

Why is it remarkable that the cicada hosts seven different species of bacteria – including obligate symbionts, facultative symbionts and even pathogens – and how could this diversity explain its adaptability?

Obligate symbiotic bacteria adapt to their insect host over long periods of time to such an extent that they can no longer exist without it. In the course of co-evolution, their genomes shrink as genes that are no longer needed for survival outside the host are lost. Facultative symbionts have not adapted as strongly to their host and are also viable without the host. The transmitted bacteria CAP and CPS can reproduce both in the host plants and in the insects. While they cause disease in the host plants and thereby weaken their defences against sap-sucking insects, they benefit the transmitted host insects. We assume that all identified bacterial species increase the fitness of the reed glasswing cicada.

How could the fact that the cicada balances its diet through its microbes explain why it can now move on to so many plants – and what does this mean for the future of pest outbreaks?

Plant sap-sucking insects live on a deficient diet that is high in sugar but low in protein, which is why the production of vitamins and other essential substances is also limited. The nutritional supplements produced by the microbes promote the fitness and reproductive potential of the cicadas. The expanding adaptive potential of reed glasswing cicadas and other insect pests threatens agriculture and poses growing challenges for farmers.

In times of climate change, more and more ‘new pests’ are emerging. Can your study help to better understand and predict such developments?

Previous studies (Behrmann et al. 2021) on sugar beet in Hesse, Bavaria, Baden-Württemberg and Rhineland-Palatinate have shown that the spread of SBR is associated with the spread of the reed glasswing cicada and is likely to be promoted by climate change. We assume that other native insect species will emerge as pests in the future as they spread in the wake of climate change.

What specific approaches to sustainable plant protection could result from your findings?

Since plant pathogens can also be transmitted by other insect species, research is currently being conducted to determine whether crops that are resistant or tolerant to pathogens can be bred. Another approach is the development of new methods that can be used to specifically eliminate plant pathogens or the essential symbionts of vector insects. We hope that the cicadas' dependence on their symbionts can be exploited as a weak point for the development of an innovative control option.

What further questions do you plan to investigate now – and what new methods or technologies will you use to do so?

First, we are investigating whether cicadas can inject substances into the host plant with their saliva that weaken its defences. In addition to transcriptome and proteome analyses, chemical analyses are also being carried out. We are also investigating whether cicada saliva differs when they infest different host systems. In order to investigate the function of individual saliva proteins, their production in the salivary gland will be inhibited using RNA interference. For this purpose, so-called double-stranded RNAs (dsRNAs) will be injected against the target gene. We are currently developing dsRNA-based sprays for the targeted and environmentally friendly control of reed glasswing cicadas and other pests.

 

Publications:

Behrmann S, Schwind M, Schieler M, Vilcinskas A, Martinez O, Lee KZ, Lang C. (2021). 

Spread of bacterial and virus yellowing diseases of sugar beet in South and Central Germany from 2017–2020.

Sugar Industry 46, 476–485; https://doiorg/ 10.36961/si27343

 

Behrmann S, Witczak N, Lang C, Schieler M, Dettweiler A, Kleinhenz B, Schwind M, Vilcinskas A, Lee KZ. (2022).

Biology and rearing of the planthopper Pentastiridius leporinus, an emerging pest in sugar beets.

Insects 13, 656; doi.org/10.3390/insects13070656

 

Behrmann S, Rinklef A, Lang C, Vilcinskas A, Lee KZ. (2023).

Potato (Solanum tuberosum) as a new host for Pentastiridius leporinus (Hemiptera: Cixiidae) and Candidatus Arsenophonus phytopathogenicus.

Insects 14, 281; doi: 10.3390/insects1403028.

 

Rinklef A, Behrmann S, Löffler D, Erner J, Meyer MV, Lang C, Vilcinskas A, Lee, K.-Z. (2024).

Prevalence in potato of ‘Candidatus Arsenophonus Phytopathogenicus’ and ‘Candidatus Phytoplasma Solani’ and their transmission via adult Pentastiridius leporinus.

Insects 15 (4): 275; doi: 10.3390/insects15040275.