Use of Fungus Found Effective Against Carriers of Xylella

Summary

Preliminary field trial results show that the Beauveria bassiana fun­gus is effec­tive against the meadow spit­tle­bug, a car­rier of Xylella fas­tidiosa pauca, and researcher Claudio Cantini believes this could be a sus­tain­able solu­tion to com­bat the spread of the dis­ease asso­ci­ated with olive quick decline syn­drome. Cantini’s ongo­ing exper­i­ments involve apply­ing the fun­gus-based prod­uct to spit­tle­bug lar­vae in olive groves to decrease insect pop­u­la­tions and poten­tially open up new pos­si­bil­i­ties for using fungi against Xylella car­ri­ers.

Preliminary results of a field trial demon­strated that the Beauveria bassiana fun­gus appeared to be ben­e­fi­cial against the meadow spit­tle­bug, a known car­rier of Xylella fas­tidiosa pauca.

Claudio Cantini, a researcher at the Italian National Research Council’s Institute of BioEconomy, said the tests were a good first step in find­ing a sus­tain­able solu­tion to curb the spread of the dis­ease, which is asso­ci­ated with olive quick decline syn­drome (OQDS).

“The exper­i­men­ta­tion was car­ried out in the frame of the LIFE Resilience project, which aims to find sus­tain­able solu­tions to curb the spread of Xylella fas­tidiosa in inten­sive olive and almond groves,” Cantini said. ​“Then, we are imple­ment­ing the infor­ma­tion obtained by the large E.U.-funded research projects on Xylella, in order to find and com­mu­ni­cate to farm­ers sus­tain­able agro­nomic prac­tices, from actions that increase soil vital­ity to plant treat­ments, with the aim of enhanc­ing the resilience of trees to pests.”

As part of the three-year project, Cantini started to mon­i­tor the pres­ence of the meadow spit­tle­bug in var­i­ous olive groves in Follonica, Tuscany, where he noticed a high pres­ence of this insect in some areas, with sig­nif­i­cant dif­fer­ences in pop­u­la­tion den­sity between adja­cent zones.

“I started to do lit­tle pre­lim­i­nary tests with prod­ucts allowed in organic farm­ing, based on the infor­ma­tion gath­ered in Puglia,” Cantini explained. ​“I knew that a prod­uct based on the fun­gus Beauveria bassiana, which attacks var­i­ous types of insects, works well in a humid envi­ron­ment, and then I applied it, along with other prod­ucts, on the foam pro­duced by spit­tle­bugs.

After a week, the researchers noticed that the fun­gus-based prod­uct had a greater effect than a pyrethroid insec­ti­cide used as a pos­i­tive con­trol, as in some cases the foam dis­ap­peared, in other cases, the num­ber of insects decreased.

“The reduc­tion com­pared to the con­trol was 80 per­cent,” Cantini noted. ​“The fun­gus ger­mi­nated, pro­duced hyphae, passed through the insect’s cuti­cle, pen­e­trated and par­a­sitized it, caus­ing it to die.”

The prod­uct should be applied when spit­tle­bug lar­vae are present, there­fore, depend­ing on the area, between the end of April and mid-May. Considering that the spit­tle­bug lar­vae pro­duce the foam as pro­tec­tion, a com­mon mis­take fight­ing them is to apply sub­stances such as sul­fur.

“In those cases, since the spit­tle­bug feels some­thing unpleas­ant within its shel­ter, it moves away to pro­duce another foam nest, and the foam pro­duc­tion increases fur­ther,” Cantini said. ​“The dis­cov­ery of the action of fungi on insects dates back to the 1800s, but we still do not know all the effects on all the insects, and we believe that this exper­i­men­ta­tion could open new sce­nar­ios to the use of fungi against the car­ri­ers of Xylella and there­fore the spread of the bac­terium.”

“We feel a sense of urgency to com­mu­ni­cate this pre­lim­i­nary infor­ma­tion,” he added. ​“I sup­pose there will be some crit­i­cism over the fact that we released pre­lim­i­nary data that still need to be con­firmed, but I did not want to wait to release data that could be use­ful.”

Cantini said that he is draft­ing a short com­mu­ni­ca­tion with the sup­port of an ento­mol­o­gist, ​“so that next year, any­one in the sci­en­tific com­mu­nity can inves­ti­gate, ver­ify, and test this or other fun­gal strains and prod­ucts of dif­fer­ent com­pa­nies, remain­ing inde­pen­dent.”

The researcher believes that the dis­clo­sure of these results has a social util­ity, as it paves the way for fur­ther ver­i­fi­ca­tions by research insti­tu­tions and com­pa­nies.

“In my opin­ion, it is impor­tant to dis­sem­i­nate this type of solu­tions, espe­cially in light of what is sug­gested by the European Food Security Agency, namely that it will be dif­fi­cult to com­pletely get rid of Xylella, and there­fore it is nec­es­sary to care­fully mon­i­tor the plants and the pop­u­la­tion of insects to curb the prob­lem.”

Experiments with Beauveria bassiana will con­tinue in another tra­di­tional olive grove, sim­i­lar to those in Puglia, and in super-inten­sive cul­ti­va­tion of Arbequina.

“We pur­chased a hyper­spec­tral cam­era, and we are plan­ning to begin mon­i­tor­ing with drones as soon as we have final­ized the data col­lec­tion pro­ce­dure,” Cantini said.

• LIFE Resilience


• ANSA