It is a widely held view that we should not intervene in or "police" nature, in part because we cannot know the long-term impacts of intervention and we are likely do as much harm as good.

But of course, humans are already policing nature in a range of ways. One example is the biological control measure known as Rabbit hemorrhagic disease, popularly known as "calicivirus". It is currently being actively released into wild rabbit populations in Australia and New Zealand to reduce their impact on native fauna (not without controversy, because the disease appears to cause intense suffering).

Those familiar with Australia know that we have a rather unfortunate history of biological control measures. Most infamously we introduced the cane toad to kill the cane beetle which was threatening sugarcane plantations, only to see the cane toad devastate native wildlife across northern Australia.

My question: could such biological control measures ever be used to reduce wild animal suffering? It is unclear that Rabbit hemorrhagic disease reduces suffering (and it could well increase it), but could we conceive of a biological agent (viral, fungal, plant, insect) that conceivably could?

Yes! Does the sterile insect technique count? We could reduce a population of insects with it (perhaps if we wanted less r-selected organisms and more k-selected or something)