I hate to say it, but getting rid of mosquitos would probably have bigger consequences than that. The females are the only ones sucking blood, the males on the other hand help pollinate plants, exterminating them could potentially affect our food production lines...
... But not gonna lie I'd still genocide the fuckers, ecological damage be damned.
Most positive effects on the planet but not humans?
Cattle, they're a major source of greenhouse gasses, as are all the industries built around growing, processing, and transporting them.
I'm off the opinion that no animal would be beneficial to remove. In almost every instance where we have exterminated a species there has been negative unanticipated consequences. Even mosquitos and bed bugs, there are predators that eat them and subsequent predators that eat them and so on. It's kind of like the butterfly effect. It's a balance formed from eons of coexistence that is not to be tampered with. There is so many examples where scientists try to introduce an animal to exterminate another that has gone horribly wrong. Regardless of my opinion, all living things have a part in our world. I'm not a vegetarian btw, but I do use Arch.
Deleting all mosquitoes would have a significant impact on the environment, many birds and spiders mainly prey on them. Delete just mosquitoes that bite humans. It's a much narrower range and wouldn't affect the environment as much.
I think I'm going to go with Africanized honeybees. My understanding is they're a man-made calamity, so pressing the delete key on them wouldn't like, upset the circle of life and piss off Mufasa or whatever.
Hard to say. Mosquitos, is probably not one of them because even as much as we hate them, many animals prey on them, so unless other insect replaces them as a food source for those animals, them disappearing would probably affect many other species and subsequently, other species that may feed or depend in some form on those that feed on mosquitos.
My answer would probably be ticks, since I don't think there's many animals that feed on them and their only usefulness is population control, which should be doable by other species either way.
Edit: bed bugs as well, since it was mentioned by other commenters, I hate those fuckers and last I checked they weren't any animal's primary food source.
Any change to the biodiversity on our planet will have a negative effect. What is a pest to you is food for another species, or a pollinator, or any of dozens of valuable purposes.
Obviously worms in general are needed, but any big group of mainly parasitic ones I could happily delete without a second thought. Ideally let's also destroy any records of their existence.
I like the thought of an animal that already existed, terrifying, gruesome and truly terrible. But we humans were given a wish to extinguish a single type of animal from the face of the earth. And so we whose. And all memory of this horror from the dark was lost as it was cast into oblivion and humanity was relieved from its existence. Now all we are left with are in comparison cuddly squeaky companions of the animal kingdom and all is well, even the animals are glad to got rid of the horror. And now you ask that question when everything truly necessary was already done and now we ponder which one is the worst when all is well.
Humans. Can you imagine how happy all of nature's spicies would be to get rid of this murderous polluting ravaging selfish disease of species called human? All animals to start to breath clean air, restore their trees and natural habitat, slowly recover their climate, and the fish thriving without plastic , toxic waste and oil pollution.
It is the best animal to delete for positive outcome no other choice comes close.
Wasps. You can kill the mosquitoes with tricks atleast, wear essential oils or lotions, use those fly killer lights.
I do not like honeybees or bumblebees for their sting, but atleast they are docile if unharmed and careful, and even great for nature and pollination. I do not hate them like I hate wasps/hornets.