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* Froghoppers (Cercopidae)
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 Cercopis vulnerata
Is grapevine an accepted host for these insect 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 Graphocephala 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 Rhododendron and grapevine plants coexist
11 THANK YOU … for your attention!
Funded by: In collaboration of:
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