Feeding habits of Central European candidate vectors of Xylella fastidiosa on grapevine

A. Markheiser1, D. Cornara2,3, A. Fereres2, M. Maixner1

1 Julius Kühn-Institut (JKI), Institute for Plant Protection in Fruit Crops and Viticulture Siebeldingen, Germany 2 Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Cientificas (ICA-CSIC), Madrid, Spain 3 International Centre for Advanced Mediterranean Agronomic Studies - Institute of Bari (CIHEAM-Bari), Valenzano, Italy CANDIDATE VECTORS OF XYLELLA FASTIDIOSA IN CENTRAL EUROPE

Hemiptera - Europe Germany Auchenorrhyncha (Cicadomorpha)

Cicadas (Cicadidae)

Spittlebugs 104 26 (Aphrophoridae) species* species* ()

Sharpshooters (Cicadellidae: Cicadellinae)

*https://faunaeur.org; Meinecke (2015); EFSA Panel (2015), Cornara et al. (2020) Ent Gen

2 IDENTIFICATION OF CANDIDATE VECTORS FOR PIERCE DISEASE (PD) IN VINEYARDS

Active sampling – Sweep net + aspirator

◼ Two winegrowing regions in Germany ◼ Biweekly (30 x 5 sweeps) on the vine foliage and ground vegetation ◼ May to October 2017-2019

3 PREVALENT CANDIDATE VECTOR SPECIES IN VINEYARDS (2018, 4 LOCATIONS)

Aphrophoridae

Philaenus spumarius Neophilaenus campestris Aphrophora alni

Cicadellidae: Cercopidae Cicadellinae

Cicadellla viridis vulnerata

Is grapevine an accepted host for these species?

Are the any differences between spittlebugs and sharpshooters in feeding?

4 ASSESSING FEEDING HABITS OF CANDIDATE VECTORS ON GRAPEVINE

DC-EPG (Direct Current- Electrical Penetration Graph)

Relevant candidate vector species (15 males + 15 females)

Philaenus spumarius Neophilaenus campestris Cicadella viridis fennahi 6 h EPG-recording

5 ASSESSING FEEDING HABITS OF CANDIDATE VECTORS BY DC-EPG

◼ Six EPG-waveforms characterized for P. spumarius (Cornara et al. 2018):

np: non-probing C: pathway Xc: xylem contact Xi: xylem ingestion N: pathway interruption R: resting

◼ Characteristics could be found in various plant species (Cornara et al. 2020; Markheiser et al. 2020)

◼ Comparable waveforms identified for other spittlebugs and sharpshooters (Cornara et al. 2020; Cornara et al. 2021; Plant vessel xylem others/none Markheiser et al. in prep)

6 FEEDING HABITS OF CANDIDATE VECTORS ON GRAPEVINE

Markheiser et al. (2021) in prep

7 VARIABLE XYLEM INGESTION QUALITY

High frequency xylem ingestion (Xi) Earlier, both considered Xi! (Cornara et al. 2018)

Varying xylem fluid intake and potentially bacterial cells of X. fastidiosa? ≥ 0.1 Hz

Low frequency xylem ingestion (LF) Attachement of X. fastidiosa in the cibarium with respect to the variable flow rate?

< 0.1 Hz

Cornara et al. (2017), J Pe Sc

8 XYLEM INGESTION OF CANDIDATE VECTORS ON GRAPEVINE (WAVEFORMS Xi + LF)

WDI: Waveformduration per insect

a a a a

a b a b

b b a c

a a c b

a, b: Significant differences in WDI between insect species and sex within one waveform according to linear model (LM) and post-hoc comparison by estimated marginal means, Tukey-test (p<0.05, n=30) 9 PROBING SUCCESS OF SPITTLEBUGS AND SHARPSHOOTERS ON GRAPEVINE

Successful probe (EPG-record)

a a b b a a a a a ab ab a

a

a Unsuccessful probe (EPG-record) c b a bc a bc b ab a a

a, b, c: Significant differences within one kind of probe between insect species and sexes according to generalized linear model (GLM) with negativ binomial distribution and post-hoc comparison by estimated marginal means, Tukey-test (p<0.05, n=15) 10 SUMMARY AND CONCLUSION

◼ P. spumarius, N. campestris and C. viridis are not only present in vineyards, but feed on vine and thus pose a risk for spreading X. fastidiosa within vineyards

◼ The sharpshooters performed in grapevine more successful probes than the spittlebugs P. spumarius and N. campestris

◼ Differences in feeding quality e.g. Xi/LF between spittlebugs and sharpshooters verified, possibly triggering the intake of bacterial cells

◼ The introduced Nearctic Graphocephala fennahi, a member of the same genus as the American PD- vector G. atropunctata, may be relevant in areas were and grapevine plants coexist

11 THANK YOU … for your attention!

Funded by: In collaboration of:

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