Occurrence in Morocco of potential vectors of Xylella fastidiosa that may contribute to the active spread of the bacteria

Abstract

Summary The bacterium Xylella fastidiosa represents a potential risk to the Moroccan flora. For this reason, several surveys were conducted in 2019 and 2020 to assess its occurrence and to establish an inventory of its potential insect vectors with emphasis on their characterization and importance from 85 sites in 25 provinces across the country. Using a sweeping net, 2604 specimens belonging to the Auchenorrhyncha suborder (Hemiptera) were collected. A total of 213 samples from different crops, including two ornamental species Nerium oleander and Polygala spp., were sampled and tested for the presence of X. fastidiosa by ELISA and PCR techniques during the same period within the same surveyed provinces (plus two additional ones, i.e. 27 provinces). Aphrophoridae species were mainly located in the northern part of Morocco where five potential insect vectors occur, namely Philaenus tesselatus, P. maghresignus, Philaenus sp., Neophilaenus campestris and N. lineatus. Philaenus tesselatus was the most important spittlebug recorded with uneven occurrence throughout the country. Philaenus spumarius has not been found in the present surveys which could indicate that it has been replaced by P. tesselatus. Therefore, the latter should be considered as the main potential insect vector of X. fastidiosa in Morocco. Current status and importance of spittlebugs, sharpshooter-leafhoppers, treehoppers and planthoppers are given. ELISA and PCR results did not show any positive results, which may be seen as good news indicating that X. fastidiosa was not found in Morocco. Regarding occurrence and importance of P. tesselatus in Morocco, pest risk analysis of X. fastidiosa in the country should be revised. Our findings highlight the factors that would contribute to the active spread of the X. fastidiosa once introduced into the country.