Nada,
Some things that come in pairs for the left and right side of our body (such as jeans, socks, shorts, shoes, spectacles) and are always written in the plural form. Therefore, they are paired with a plural verb (The jeans are made in Italy.)
If you are referring to a specific pair, then you have to write: "This pair of jeans is made in Italy." because you are now referring to one thing.