Philaenus tesselatus (Hemiptera: Aphrophoridae), the main potential vector of Xylella fastidiosa in Morocco: seasonal abundance, phenology and host-plant colonization by nymphs

Abstract

Summary The bacterium Xylella fastidiosa presents a potential risk to the Moroccan flora, particularly for the citrus, olive, almond and grapevine industries. Philaenus tesselatus, the meadow spittlebug, is the most important Moroccan spittlebug, though recorded with uneven occurrence and considered to be the main potential insect vector of X. fastidiosa. A three-year field survey (2019 to 2021) was conducted at three sites in the provinces of Larache and Kenitra in northwestern Morocco, to study seasonal abundance, phenology and host-plant colonization by nymphs. Philaenus tesselatus is a univoltine species. Nymphs occurred in groundcover from end of mid-March to mid-May, with abundance peaking between end of March and mid-May. Emergence of teneral adults occurred between April and May, depending on the year. Adults were present on ground vegetation from March until early August, with the highest abundances surveyed by sweep net in April, and occurred in canopy in low abundance between the end of May and mid-September, depending on site. Both nymphal and adult abundances were significantly higher in Larache than at the other two sites. Philaenus tesselatus, the meadow spittlebug, is a polyphagous species, recorded on nine botanical families of host plant species including Asteraceae, Poaceae, Fabaceae, Polygonaceae, Apiaceae, Primulaceae, Urticaceae, Papaveraceae and Malvaceae, and 37 host plant species, of which 29 were identified. The Asteraceae were best represented. Carduus pycnocephalus, Vulpia geniculata, Anthoxanthum odoratum and Cistus salviifolius were the most suitable for this spittlebug. Avena barbata, L. foemina, Scolymus hispanicus and S. oleraceus were dominant in the herbaceous layer. Philaenus tesselatus preferred to feed on the mid-section of the host plants. A single foam can host zero to five individuals, but foams with one or two nymphs were most frequent. Implications of our findings for the setting up of a survey program to control X. fastidiosa and its vectors in case the bacterium is introduced to Morocco are discussed.