I remember reading this book as a teenager, so most likely it is a YA novel.
The premise of the story is that humanity is attempting to recolonise the Earth, after having abandoned it many generations earlier. The first colony ship to arrive has the misfortune to crash-land, separating the two pilots from the section of the ship that contains the cryogenically frozen colonists. Accompanied by the ship's AI, the pilots set out to cover the great distance standing between them and the rest of the ship.
Throughout their journey, the protagonists observe that the wildlife they encounter demonstrates surprising signs of intelligence. Whilst travelling across the ocean, the ship's AI is able to communicate with a pod of whales by translating their whale-song. The whales reveal the story's big plot twist - that after the majority of humanity had fled to the stars, the final remaining human scientists performed extensive gene splicing experiments, in order to grant all living creatures on Earth the gift of sapience.
As the protagonists finally reach the rest of their ship, the disastrous consequences of the scientists' misguided gift become apparent. The pilots are attacked by swarms of millions upon millions of insects, whose planet-encompassing hive mind doesn't take kindly to the return of humanity. Taking shelter in the ship, the pilots despair that the recolonisation effort is doomed, as the highly organised insects will have no difficulty massacring the hopelessly outnumbered colonists, just as they eliminated the final remnants of humanity that had remained on Earth years before.
In the end, the ship's AI is the one who saves the day. Having determined how to communicate with the insects, the AI travels to the heart of the hive mind, and successfully manages to negotiate a peace treaty. The story ends with the pilots preparing to awaken the frozen colonists, ready to face the challenges of sharing the Earth with countless other sapient species.