You are spending the greatest amount of time in Italy. You have no activity in any other country that would make that country the "main destination" over Italy. Italy is therefore the country responsible for deciding on your visa application.
This is specified in article 5 of the Schengen Visa Code, in particular paragraphs 1 (b), found at http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02009R0810-20160412:
(b) if the visit includes more than one destination, the Member State whose territory constitutes the main destination of the visit(s) in terms of the length or purpose of stay; or
The next paragraph makes it clear that the first country of entry comes into play only if there is no single main destination:
(c) if no main destination can be determined, the Member State whose external border the applicant intends to cross in order to enter the territory of the Member States.
You should submit your visa application to the Italian consulate responsible for your place of residence, unless Italy has no representation there, or another country has agreed to handle applications for Italy. In that case, another Schengen country will be designated to act on Italy's behalf, and you would need to submit your application to that country instead.
(source: Schengen Visa Code, article 8)