The number of arrests and criminal summonses handled by city cops last week plummeted compared to the same period in 2018 — and law enforcement sources warn it’s the “Pantaleo Effect.’’

Officer Daniel Pantaleo was fired by NYPD Commissioner James O’Neill on Aug. 19 over his role in the fatal takedown of Staten Island cigarette peddler Eric Garner, enraging police officers and their union leaders, who argue the cop was simply doing his job during an arrest.

Police Benevolent Association chief Patrick Lynch responded by angrily telling his members to “proceed with the utmost caution’’ when answering calls — and new statistics obtained by The Post on Monday suggest officers are heeding his warning.

Arrests dropped 27% between Aug. 19 — the day Pantaleo was fired — and Aug. 25 compared to the same period in 2018, with police making 3,508 busts compared to 4,827.

The number of criminal summonses issued fell nearly 29% over the same period, going from 1,655 to 1,181, the figures show.

Multiple law enforcement sources told The Post that while there is no organized slowdown, cops on the street clearly feel that the department doesn’t have their backs, so why should they needlessly put themselves on the line?

“Who wants to be the last cop standing?” a Manhattan cop said. “If someone’s in trouble and needs help or if a cop’s in trouble, obviously, you do what you have to do as a police officer. But if it’s discretionary, why put yourself in harm’s way?’’

An NYPD supervisor in Brooklyn said, “Of course it has to do with what happened to Pantaleo — cops are frustrated, upset. They feel they don’t have the backing of downtown, Police Headquarters and City Hall.

“It all goes back to cops feeling like they’re out on the street alone.’’

A Bronx cop said the stats are lower partly because officers are taking more time with calls after Pantaleo.

“They want to be more careful. They have to protect themselves because no one else is going to protect them,’’ the source said.

The Manhattan source said Garner’s case would never have happened today — because the city has told officers to back down on making such quality-of-life busts.

The Police Department said in a statement, “The brave women and men who joined the NYPD did so with a solemn promise to help people, to fight crime, and to keep New York City safe.

“These dedicated officers practice precision policing — focusing on the offenders who commit crimes, not the accumulation of raw numbers.”

Additional reporting by Tina Moore.