I’m very glad some people are finally working on this. This is one of the best suggested interventions I’ve seen in effective altruism to date. I correctly predicted that my biologist tumblr mutual nunuisancenewt would have a skeptical take though, and since he doesn’t have an account here, I will present his thoughts in his absence:
First, he’s very skeptical of the estimates for how many wild animals are affected by the new world screwworm. The only source given in your google doc is a paper which provides a statistic on the prevalence of myiasis in feral swine, which is really not enough information to conclude that myiasis is equally prevalent among all warm-blooded animals in South America. It’s plausible that screwworms are significantly more likely to target large mammals like pigs and cows to lay their eggs in, and that screwworm myiasis is rare among the small rodents and bats who make up the majority of the wild mammals in South America, since those mammals spend a lot more time in burrows and caves, and are more vulnerable to predation (making them less likely to die from parasites, and also making it a worse idea to lay eggs in them because they don’t live as long). KB Mathias cites a paper that cites another paper from 1937 that looked at 298 wild rabbits in North America prior to the eradication of the screwworm in that region, and found that 4% of them (12) were infected. This datapoint is evidence that screwworm myiasis is nearly as prevalent in smaller and more numerous wild animals than in larger and slower ones, but it is quite weak evidence. The EV estimates could easily be overstated by multiple orders of magnitude. Screwworms could conceivably affect closer to a million animals than a billion.
Secondly, there would be negative consequences for wild-animal-welfare to growing the cattle industry in South America, which this plan hinges on accomplishing. I’m extremely certain that total cattle welfare would be improved by eradicating the screwworm, despite resulting in higher cattle populations, but the expansion of cattle farming in South America would hasten the deforestation of the Amazon, which has profoundly negative ecological and climatic consequences. The Amazon is a carbon sink, and destroying more of it will worsen the effects of climate change, which is bad for wild animals on a large scale. Brian Tomasik argues here that rainforest beef production is net positive because it reduces the population of wild insects, but nunuisancenewt strenuously disagrees, (primarily) on the grounds that stable ecosystems are largely populated by specialists, who are larger, fewer in number, and practice K-selection, whereas disrupted ecosystems are largely populated by generalists, who are the reverse, and can be expected to experience more suffering. I’m not sure if this rule applies to a hectare of rainforest specifically, because of how unusually dense the wildlife is in such areas, but I would assume that habitat loss in the rainforest probably means more ecological disruption generally, affecting species across a much larger area than that which is directly affected.
He’s not concerned at all about the direct ecological effects of eliminating the screwworm, or any other parasite, since they have small and predictable effects on the ecosystem, and they represent a nutrient transfer away from large slow-breeding animals towards small fast-breeding animals, which means more animal suffering, even discounting the very serious direct harm they cause.
Myself, I’m about 90% sure the EV of expanded cattle farming in South America from reduced mortality rates is negative, and also about 90% sure that that negative EV is smaller in scale than the positive EV of reduced suffering from animals that counterfactually would have suffered myiasis and instead die of something else. But the scale of the second number is really, really uncertain without a lot more information. There’s a not-super-implausible timeline where the number of animals saved from myiasis is lower than the number of animals burned to death by rainforest clearing. I’m very interested to read the results of the Wild Animal Initative’s currently ongoing investigation on the effects of the New World Screwworm on wild animal welfare, but before then the available information seems very incomplete. I can’t find any better source on the number of animals affected by screwworm myiasis than yours. Information on wild animal suffering is frustratingly incomplete generally, and the complexity of ecosystems makes predicting the sign on wild animal interventions very, very hard. This case is no exception.
I’m very glad some people are finally working on this. This is one of the best suggested interventions I’ve seen in effective altruism to date. I correctly predicted that my biologist tumblr mutual nunuisancenewt would have a skeptical take though, and since he doesn’t have an account here, I will present his thoughts in his absence:
First, he’s very skeptical of the estimates for how many wild animals are affected by the new world screwworm. The only source given in your google doc is a paper which provides a statistic on the prevalence of myiasis in feral swine, which is really not enough information to conclude that myiasis is equally prevalent among all warm-blooded animals in South America. It’s plausible that screwworms are significantly more likely to target large mammals like pigs and cows to lay their eggs in, and that screwworm myiasis is rare among the small rodents and bats who make up the majority of the wild mammals in South America, since those mammals spend a lot more time in burrows and caves, and are more vulnerable to predation (making them less likely to die from parasites, and also making it a worse idea to lay eggs in them because they don’t live as long). KB Mathias cites a paper that cites another paper from 1937 that looked at 298 wild rabbits in North America prior to the eradication of the screwworm in that region, and found that 4% of them (12) were infected. This datapoint is evidence that screwworm myiasis is nearly as prevalent in smaller and more numerous wild animals than in larger and slower ones, but it is quite weak evidence. The EV estimates could easily be overstated by multiple orders of magnitude. Screwworms could conceivably affect closer to a million animals than a billion.
Secondly, there would be negative consequences for wild-animal-welfare to growing the cattle industry in South America, which this plan hinges on accomplishing. I’m extremely certain that total cattle welfare would be improved by eradicating the screwworm, despite resulting in higher cattle populations, but the expansion of cattle farming in South America would hasten the deforestation of the Amazon, which has profoundly negative ecological and climatic consequences. The Amazon is a carbon sink, and destroying more of it will worsen the effects of climate change, which is bad for wild animals on a large scale. Brian Tomasik argues here that rainforest beef production is net positive because it reduces the population of wild insects, but nunuisancenewt strenuously disagrees, (primarily) on the grounds that stable ecosystems are largely populated by specialists, who are larger, fewer in number, and practice K-selection, whereas disrupted ecosystems are largely populated by generalists, who are the reverse, and can be expected to experience more suffering. I’m not sure if this rule applies to a hectare of rainforest specifically, because of how unusually dense the wildlife is in such areas, but I would assume that habitat loss in the rainforest probably means more ecological disruption generally, affecting species across a much larger area than that which is directly affected.
He’s not concerned at all about the direct ecological effects of eliminating the screwworm, or any other parasite, since they have small and predictable effects on the ecosystem, and they represent a nutrient transfer away from large slow-breeding animals towards small fast-breeding animals, which means more animal suffering, even discounting the very serious direct harm they cause.
Myself, I’m about 90% sure the EV of expanded cattle farming in South America from reduced mortality rates is negative, and also about 90% sure that that negative EV is smaller in scale than the positive EV of reduced suffering from animals that counterfactually would have suffered myiasis and instead die of something else. But the scale of the second number is really, really uncertain without a lot more information. There’s a not-super-implausible timeline where the number of animals saved from myiasis is lower than the number of animals burned to death by rainforest clearing. I’m very interested to read the results of the Wild Animal Initative’s currently ongoing investigation on the effects of the New World Screwworm on wild animal welfare, but before then the available information seems very incomplete. I can’t find any better source on the number of animals affected by screwworm myiasis than yours. Information on wild animal suffering is frustratingly incomplete generally, and the complexity of ecosystems makes predicting the sign on wild animal interventions very, very hard. This case is no exception.