What are the consequences for the ecosystem can lead to the complete destruction of a separate

What are the consequences for the ecosystem can lead to the complete destruction of a separate species of predator or parasite?

In the ecosystem, each species takes its place and in the process of life plays a certain role to maintain its stability. Living organisms form trophic chains along which substances and energy are transferred. Predators and parasites are part of this chain and control the number of individuals they feed on. If the species diversity is great, then the disappearance of one species will not greatly affect the structure of the system, because the place of this species will be taken by another, feeding on the same organisms. If the species diversity is poor, then the extinction of one species will lead to an imbalance. For example, the disappearance of one species of predator will be followed by uncontrolled reproduction of consumers that feed on insects or vegetation, to the appearance of sick and wounded individuals among them. And, for example, the appearance of a large number of herbivores will lead to the destruction of vegetation and disruption of the soil structure, and then to the extinction of these herbivores due to lack of food. The disappearance of one type of parasite will lead to an increase in the number of individuals on which this species has parasitized. In addition, there will be weak and sick people among them, who will pass on their genes to their offspring, disrupting the course of natural selection.