Final answer:
The technique known as biological control involves introducing predators to regulate unwanted species populations. However, if the new species is not a specialist, it may prey on or outcompete native species, leading to decreased populations and ecological imbalances, thus becoming an invasive species.
Step-by-step explanation:
The method of introducing a predator to control the population of an unwanted species is called biological control. The population of the added species increased, leading to a decrease in several populations of other species in the ecosystem due to predation and competition for resources. When a new predator is introduced, especially if it's a generalist rather than a specialist, it can start preying on native species or outcompete them for food, habitat, or other resources, causing ecological imbalance. This unintended consequence is also linked to the fact that some species are pre-adapted to new environments and can become invasive species, thriving at the expense of native species populations and altering the ecosystem.