New York lesson

What lesson, if any, emerges from the upset New York gubernatorial race, in which Lt. Gov. Mario Cuomo defeated Mayor Edward Koch in the state's Democratic primary? Was Reaganomics a hidden factor, since Mr. Cuomo represents traditional Democratic liberalism and Mr. Koch was supportive of the administration until early this year?

In this connection it is interesting to note that Democratic incumbent Gov. Edward King, a proponent of supply-side economics, was defeated by a more liberal-to-mainstream Democrat, Michael Dukakis, in the recent Massachusetts primary. And Georgia boll weevil Democratic Congressman Billy Lee Evans was defeated in a primary where Reaganomics became an issue.

Probably the national economic factor was not as important as local considerations - and the personalities - in each of these contests. There was, for example, the outspoken statement by Mayor Koch that living in rural areas was ''a joke.'' If so, the joke turned out to be on Mr. Koch, who lost upstate New York by 100,000 votes.

It is noteworthy that polls had shown Mr. Koch out front, and that he had received the endorsement of all three major New York City papers. So the New York results may be telling candidates everywhere not to take the voting public for granted this year.