Traditional parties suffered a strong setback in Italy's local elections that ended on Monday, as various protest candidates became mayors of key cities.

In the second round in 118 municipalities, where no candidate won more than 50 percent in the first ballot, the center-left Democratic Party (PD) was defeated in Palermo as well as in Parma although it won 14 out of 26 capital cities.

Former premier Silvio Berlusconi's People of Freedom (PdL) party and its former ally Northern League, soundly defeated two weeks ago, lost a number of traditional strongholds such as Piacenza, Alessandra and Como.

But what many local analysts called "a word to the wise" was the symbolic victory in two rounds of comedian Beppe Grillo's Five-star Movement ahead of political elections scheduled for spring 2013.

The movement, made of common citizens communicating through social media, consolidated its sensational growth by contesting against mainstream parties.

Grillo's candidate Federico Pizzarotti, a 39-year-old employee at a local bank, defeated a veteran politician supported by a center-left coalition in Parma, an important city of nearly 200,000 inhabitants in central Italy.

Grillo's victory showed both rejection of corrupted traditional parties and anger towards Prime Minister Mario Monti's government in coping with the crisis only with tough austerity measures, political science professor at Bologna University Carlo Galli said.

"I do not think mainstream parties will be able to reorganize themselves before the 2013 political elections," he told Xinhua.

The country is going towards "a period of political instability," he said. Possible alliances will revolve around the only probably stable party, PD, "which however will not be sufficient to govern the country."

Grillo's candidates also won in the northern small towns of Mira and Comacchio taking advantage of a recent party funding scandal involving Northern League's leader Umberto Bossi and his family.

"Parties have talked a lot about generational change, but without concretely acting in this direction," Pizzarotti said on Tuesday, adding that as the new mayor of Parma he will use "the greatest honesty and transparency in all decisions."

He then asked journalists to leave him alone. "I have to work now," he said.

In fact, according to local analysts, it was the "fresh energy" of Grillo's candidates to attract thousands of Italians disillusioned by the escalation of scandals in the traditional political landscape of all colors.

"PD and PdL's defeat was largely predictable, although it was even more serious than expected," said Roberto D'Alimonte, a political science professor at LUISS University in Rome.

D'Alimonte pointed out that local elections have showcased the discontent of center-right voters who have either abstained or supported Grillo's candidate in protest.

"For this reason, it is possible to say that the result of general elections scheduled for the next year will especially depend on the choice of center-right voters," he said.

Experts also agreed that Grillo's symbolic victory expressed the strong will of Italians to participate actively in the rebuilding of their homeland, which is struggling amid the debt crisis, severe austerity measures and record-high unemployment.

Writer Massimo Franco, a member of the London International Institute for Strategic Studies, hopes that mainstream political parties will prove able to correctly interpret "the dynamics of a country that has sent last advice before evicting them."

"Italians have expressly said what they do not want anymore," Franco said. It will not be easy for traditional parties to attract electors in next year's vote "without seriously examining the reason of the defeat and their role in the country," he said.