I don't think there is a specific term, but I would suggest polytheocide.
Extermination
Homicide is the deliberate and unlawful killing of one person by another. Multiple is more than one.
Yes, the term often used to describe an animal killing a human is "zoonotic fatality" or "animal attack." However, in legal contexts, it may simply be classified as a fatal animal attack or an incident of wildlife-related death. There isn't a direct equivalent to "homicide" for such cases, as "homicide" specifically refers to human-on-human killing.
one concern is, that many pesticides are killing multiple insects
Yes, the movie "Texas Killing Fields" is loosely based on a real place in Texas where multiple murders occurred. There is no specific book directly tied to the movie, but there are books on true crime cases that have taken place in the Texas Killing Fields.
As specific targets? No.
Holocaust
A mass killing is often referred to as a massacre or a mass shooting, depending on the specific circumstances. It typically involves the deliberate killing of a large number of people in a single event.
Killing machine king cobra kool killers
Holocaust
ACUTE: injury/condition caused by a specific even CHRONIC: injury/condition developed over multiple events or prolonged time periods examples: ACUTE: I stepped off a curve, rolled my ankle and now it is swollen and killing me! CHRONIC: I work at a computer 40 a week for about 4 months now and my neck is KILLING me!
The expression "rat killing" likely originated from the act of physically killing rats, which was often done in large numbers or as a collective effort. It is used metaphorically to describe completing a task that is tedious, time-consuming, or involves a lot of work.