New tool to predict the optimal time of intervention to control the nymphs of Philaenus spumarius, insect vector of Xylella fastidiosa in Europe Researchers from two CSIC institutes developed a predictive tool that can help limit the populations of the main insect vector of the bacterium Xylella fastidiosa, which causes diseases that seriously affect several key crops in our agriculture, such as olive trees, vines and almond trees.  Philaenus spumarius is a polyphagous insect of the group commonly known as cicadas, which is present in practically the entire northern hemisphere. For a long time, it was unknown to agriculture, but the detection of the X. fastidiosa bacterium in Europe in 2013 has considerably increased the interest in its study, since this insect is the main vector of this bacterium in Europe. In particular, strains of this bacterium have devastated olive plantations in Apulia (Italy), causing the uprooting of millions of olive trees, as well as thousands of almond trees in Mallorca and Alicante and at this moment it poses a serious threat to both vineyards and almond and also olive groves in Andalusia. Understanding the life cycle and phenology of P. spumarius is key to limiting the spread of X. fastidiosa and its impact on different plantations.  The study recently published in the journal Environmental Entomology of the American Society for Entomology (ESA) was conducted between the Institute of Agricultural Sciences (ICA-CSIC) and the Institute for Cross-Disciplinary Physics and Complex Systems (IFISC, CSIC-UIB). This study, based on field data obtained in different localities of the Iberian Peninsula, proposes a mathematical model with which a tool has been built to predict the time of hatching of P. spumarius eggs. The research team monitored P. spumarius eggs, from oviposition to hatching, along with daily temperatures and relative humidities at four field locations in the Community of Madrid that were at different altitudes. The data collected were used to construct a model of growth as a function of cumulative temperature (degree-days) to predict egg hatching of the insect in the Iberian Peninsula. In addition, the model was validated with field observations made at different locations in Spain.  The resulting model has been used to develop a decision support tool to calculate the optimal time to apply control measures on P. spumarius nymphs, such as surface tillage or weeding. The results suggest that applying control measures on two different dates would optimize the elimination of nymph populations in the field. This would considerably reduce the risk of disease spread.  The tool developed calculates the probability of hatching of P. spumarius eggs using the information provided by AEMET stations, which can be accessed through this link: https://pseggs.ifisc.uib-csic.es/.  From this information it is possible to determine the appropriate times to apply the 2 treatments proposed as optimal in the work, when the hatching probabilities are 0.35-0.4 and 0.9, respectively.Clara Lago et al., Degree-day-based model to predict egg hatching of Philaenus spumarius (Hemiptera: Aphrophoridae), the main vector of Xylella fastidiosa in Europe, Environmental Entomology, 2023; nvad013, https://doi.org/10.1093/ee/nvad013 http://ifisc.uib-csic.es/en/news/philaenus-spumarius-insect-vector-xylella-f...