LOS ANGELES (AP) — Scientists assessing long-term efforts to eradicate invasive ants on the Channel Islands off the Southern California coast have enlisted a four-legged expert to make sure a project to kill off the destructive pests has succeeded.

A yellow Labrador named Tobias has lived for three months with a handler on Santa Cruz Island. The specially trained dog keeps its snout to the ground, rooting through more than 1.6 square miles (4.1 square kilometers) of underbrush, searching for nests of Argentine ants that threatened the ecosystem after they were introduced decades ago.

Christina...