Xylella Fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy

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Abundance of spittlebug nymphs (Hemiptera: Aphrophoridae) in Trás-osMontes region, Portugal

Publication . Rodrigues, Isabel; Villa, Maria; Baptista, Paula; Pereira, J.A.

Spittlebugs (Hemiptera: Aphrophoridae) are considered the main European vector of Xylella fastidiosa, a gram-negative bacterium responsible for serious diseases in important agronomic crops. Nymphs of spittlebugs develop in vegetation cover where they produce a spittle mass that provides protection from natural enemies and solar radiation. This spittle mass is visible to the unaided eye which facilitates its monitoring, the understanding of nymph’s dynamics and the implementation of control strategies against X. fastidiosa. In this context, the goals of this work were monitoring the abundance of spittlebug nymphs and identifying the host plants in the natural ground cover in the Trásos-Montes region, Portugal. For that, the presence, number of spittles per plant, number of nymphs per spittle, and spittle position low, medium or high were recorded over a sample unit of 100 × 25 cm in one olive grove (spring 2017 and 2018), in one almond orchard and one vine (spring 2018) from Trás-os-Montes. Thirty sample units randomly distributed over a transect covering 1 ha were selected per sampling date and sampling site. The peak of spittlebug nymphs occurred in the middle of April and first weeks of May in 2017 and 2018, respectively, in all sampling sites. Nine spittle masses and a mean of 1.93 ± 0.35 plants with spittle per m2 were recorded respectively in 2017 and 2018. In 2017, Crepis vesicaria L. and Bromus diandrus Roth were the most attacked species. In 2018, the presence of nymphs of the genus Neophilaenus was more abundant in the vine, presenting a mean of 0.60 ± 0.19 nymphs per m2, while Philaenus nymphs showed a higher abundance in the olive grove, presenting a mean of 0.17 ± 0.08 nymphs per m2. Nymphs of the genus Neophilaenus were identified with high frequency in the species Avena barbata subsp. lusitanica (Tab. Morais) Romero Zarco and Cynodon dactylon (L.) Pers and the Philaenus nymphs were identified more frequently in the species Erodium cicutarium (L.) L´Her. and in the genus Trifollium spp. It was verified that the number of nymphs registered in the Trás-os-Montes region was much lower than the numbers reported in other European regions, being necessary more years of study to understand the dynamics of spittlebug nymphs.

2019Conference object

Open access

Preferência de ninfas de Philaenus spumarius, potencial vetor de Xylella fastidiosa, pelas espécies do coberto vegetal em olivais em Trás-os-Montes

Publication . Villa, Maria; Reis, Carlos; Baptista, Paula; Pereira, J.A.

Xylella fastidosa é uma bactéria ftopatogenica agente causal do Síndrome do Declínio Rápido da Oliveira, que afeta numerosas espécies de plantas cultivadas e selvagens. Na Europa, X. fastidiosa foi detetada pela primeira vez em 2013 em olivais do sul de Itália, e posteriormente em diferentes regiões de França, Alemanha e Espanha. A 10 de abril de 2018 foi noticiada a existência de um foco de infeção em oliveira na região de Madrid (Espanha). Esta bactéria é transmitida por insetos sugadores de xilema das plantas, tendo o Aphrophoridae Philaenus spumarius L. (1758) sido identificado em Itália como o vetor principal da doença. Este inseto encontra-se amplamente distribuído em Portugal e a sua presença nos olivais pode trazer riscos associados de transmissão de doença. A fase imatura deste inseto ocorre em plantas da vegetação espontânea. Assim, com o presente trabalho pretendeu-se identificar a preferência das ninfas de P. spumarius pelas plantas espontâneas vulgarmente existentes nos olivais transmontanos. O trabalho decorreu durante a primavera de 2017, estando a ser repetido em 2018, em dois olivais, sendo que um deles foi parcialmente queimado no verão de 2016 e apresenta cobertura vegetal anormalmente vigorosa. São registados o número de plantas com espumas de P. spumarius, o número de espumas por planta e a sua posição na planta, e o número de ninfas por espuma. Até ao momento foram identificadas cerca de 90 espécies de plantas pertencentes a mais de 18 famílias, sendo as mais abundantes Poaceae, Fabaceae e Asteraceae. Mais do 85% das espumas foram registadas no olival parcialmente queimado, que apresentava maior cobertura vegetal, maior cobertura de Fabaceae e menor de Poaceae. As espumas foram encontradas principalmente em plantas pertencentes às famílias Asteraceae e Fabaceae. Várias famílias de plantas nunca apresentaram espumas. Os resultados obtidos permitirão uma gestão mais eficiente das coberturas vegetais com o objetivo de diminuir o risco de infeção por X. fastidiosa em olivais portugueses.

2018Conference object

Open access

Climate tolerances of Philaenus spumarius should be considered in risk assessment of disease outbreaks related to Xylella fastidiosa

Publication . Godefroid, Martin; Morente, Marina; Schartel, Tyler E.; Cornara, Daniele; Purcell, Alexander H.; Gallego Cambronero, Diego; Moreno, Aránzazu; Pereira, J.A.; Fereres, Alberto

The bacterium Xylella fastidiosa (Xf) is an invasive insect-borne pathogen, which causes lethal diseases to important crops including olives, citrus, almonds and grapes as well as numerous forest, ornamental, and uncultivated plants. Outbreaks of Xf-related plant diseases are currently occurring in the Mediterranean region, causing substantial losses to various agricultural sectors. Several models have recently been published to identify which regions are at highest risk in Europe; however, such models did not consider the insect vectors, which constitute the key driver of short-range Xf spread. We fitted bioclimatic species distribution models to depict the macroclimatic preferences of the meadow spittlebug Philaenus spumarius L. (1978) (Hemiptera: Aphrophoridae), the major epidemiologically relevant vector currently responsible for Xf spread in the Europe. Many regions of Western Europe and Mediterranean basin are predicted by models as highly climatically suitable for this vector, including all regions where severe Xf have occurred so far. Conversely, the driest and warmest areas of the Mediterranean basin are predicted as little suitable for P. spumarius. Models forecast that agricultural-important parts of the southern Mediterranean area might experience a substantial decrease in climatic suitability for P. spumarius by the period 2040–2060. Areas predicted as highly suitable just for the bacterium but not optimal for this vector are apparently still free of severe Xf outbreaks, suggesting that climate tolerances of P. spumarius might partly explain the current spatial pattern of Xf outbreaks in Europe and should always be considered in further risk assessments.

2021Journal article

Open access

Intermediate fragmentation surrounding vineyards favours the Coleoptera community within the crop

Publication . Taranto, Luisa; Rodrigues, Isabel; Santos, Sónia Marina Figueiredo Abrantes; Villa, Maria; Pereira, J.A.

Insects of the order Coleoptera play an essential role in agricultural sustainability by supporting many ecosystem services (such as biological control, nutrient cycling or pollination). In agroecosystems, the Coleoptera community may be influenced by the surrounding landscape, which can provide living resources, like food or shelter, during different seasons, originating spillover movements between different environments. The present study aimed to evaluate the response of the Coleoptera community to the landscape surrounding vineyards at different buffers. For that, Coleoptera were sampled in six wine protected designation of origin (PDO) regions of Portugal (35 vineyards), and landscape configuration and composition metrics were calculated at buffers of 500, 750, 1000, 1500 and 2000 m radii around the vineyards. In total, 2954 Coleoptera individuals belonging to 36 families were collected. The most abundant families were Chrysomelidae, Coccinellidae and Latridiidae. Results indicated that intermediate habitat fragmentation levels, particularly in semi-natural areas and vineyards, favoured Coleoptera biodiversity in vine-producing regions. Moreover, the range of activity of Coleoptera seems to be larger This work constitutes an important contribution to understanding the response of the Coleoptera community to the landscape context in vineyards in Portugal and contributes to the theoretical framework about the influence of habitat fragmentation on biodiversity.

2023Journal article

Open access

Olfactory responses to volatile organic compounds and movement parameters of Philaenus spumarius and Cicadella viridis

Publication . Rodrigues, Isabel; Benhadi-Marín, Jacinto; Rodrigues, Nuno; Baptista, Paula; Pereira, J.A.

Xylella fastidiosa, the causal agent of several diseases in crops of economic interest, could be rapidly transmitted and spread throughout the agroecosystem landscape by xylem sap-feeding insects. Chemical signals in the environment drive the behaviour of insects. Attractive or repulsive responses to signals may affect insects’ fitness, survival and reproduction, and elicit different movement patterns. Specific movement patterns derived from olfactory cues towards the selection of plants for feeding may trigger the transmission of the pathogen by the insect. Thus, understanding vectors’ olfactory response and movement parameters are of utmost importance. This work aimed to assess the olfactory response of Philaenus spumarius and Cicadella viridis adults to two Volatile Organic Compounds (VOCs) (cis-3- hexenyl acetate and cis-3- hexen- 1- ol) present in almond, olive and vine leaves. Insects’ behavioural responses were conducted in a four-arm olfactometer, and the two aforementioned VOCs were tested at different concentrations (5, 10, 20 and 30 μg/μl). At the lowest concentration, females of P. spumarius were significantly attracted by the two VOCs. At the highest concentrations, no significant differences were detected among treatments. Cicadella viridis individuals showed no significant differences in their choice at any concentration. Additionally, the walking movement of these insects was also studied in the absence of food. Females of P. spumarius and C. viridis can walk significantly more at a significantly higher velocity than males. Knowledge of the olfactory response of X. fastidiosa vectors and their movement parameters can be essential to develop new tools to limit the spread of this phytopathogen.

2022Journal article

Open access