Abundance of choice, abundance of complexity, abundance of competitors, abundance of debate and of decisions, the list goes on ---- plenticide happens because of primal fear from one or all of these reasons.
It needn't involve killing humans or even living beings - killing ideas and choices will do just as well in providing these plenticiders with their sought for relief.
A nuclear war or a big comet might destroy all life on it and even destroy its atmosphere forever - but this mundicide - death of a planet's life - because it was not a selective pruning back but rather a total loss of life and choice.
A tiny bit more deliberate is the incidental killing of lifeforms as human activity expands - ecocide - because we have been warned repeatedly that expanding these activities will lead to these deaths.
Criminal neglect or culpable negligence seems to be the terms we are looking for to describe these planet-wide crimes.
Fear of overwhelming abundance
But plenticide refers to deliberate plans to kill lifeforms to deliberately reduce variety, debate, competition, complexity.
So the Holocaust system took up a well known insecticide Zyklon-B and used it to kill off human 'competitors' (Jews , Romas, Slavs) as well as farm bugs - because they felt both made life much more chaotic and complex for the German nation during WWII.
We fail ourselves if we only call such killing a genocide, because that says only what/who was killed and not really why.
That 'why' comes down to plenticide...