Aphrophoridae (Hemiptera) vectors of Xylella fastidiosa pauca OQDS juvenile quantitative sampling

Few Aphrophoridae, namely Philaenus spumarius, P. italosignus and Neophilaenus campestris transmit Xylella fastidiosa pauca ST53 causing the Apulian OQDS episode. Vector control is the effective, least impacting and sustainable action to manage and contain insect-borne pathogens. One of us (Porcelli) presented the first draft of a Aphrophoridae vector control strategy during the Symposium in Gallipoli. The same author proposed a more elaborated scheme for EFSA and in POnTE H2020 project kick-off. The strategy targets juvenile spittlebugs for vector control also because they are out of the olives trees, unable to transmit and far in time from transmission risks, pretty delicate and susceptible to several control means, relatively easy to count ex ante and ex post control action, with a control window wide enough to allow a second chance in case of first control action failure. Vector population size is one of the few key factor needed to shape a rational control strategy, but traditional adult sweeping net sampling or juvenile seeking by a looking glass do not gather the needed quantitative data. From 2016 we faced the need for novel sampling techniques focused on juvenile spittlebugs because naiades and nymphs are into the spittle and almost immotile, thus appearing the best possible instars for population measure. First experiments by flotation consisted in collecting herbs in olive orchards, either managed or abandoned, and in urban areas from within a transect and to wash the plants in water until any further juvenile was sieved out from the bath. Reducing the transect size from 0.25 to 0.04 m2 and adding NaCl and Sucrose to increase the juvenile floating we suggest a method simple and effective that recorded the highest Aphrophoridae juvenile population (about 10,470,000 per ha). Flotation demonstrated striking differences in population among managed, unmanaged groves and urban environments.