A chance to speak up for mosquito eradication in the USA (by June 5)

Aaron Gertler 🔸

I am not at all an expert in mosquitoes, but I think it would be hard to figure out more than the direct effects on mosquitoes, which are sex specific. A few assorted thoughts:

Scale: the Google Debug program website says when applied, they need to releases 100s of thousands to millions of mosquitoes each week, so the scale is reasonably high.
They release only male mosquitoes, but it's not possible to rear only male mosquitoes (AFAIK), so they are killing all the females. The Debug project's Nature Biotechnology article says that they sort males from females as pupae (which may involve low welfare cost, I don't know when sentience emerges in insects and especially whether it's possible to feel pain as a pupa), and again as adults (which, if insects are sentient, probably is painful for those females). They report that 95% of females are removed as pupae, so a much smaller amount are being killed as adults. About 2.5% of what make it through the first sort are females, so we can estimate that to achieve daily releases of ~ 75k males, ~2000 females are killed as adults daily. The paper does not seem to report how the females are killed for either pupae or adults, which is a big gap from a welfare perspective.
According to this, Wolbachia often shorten lifespans. But several strains also seem to enhance immune function and have other mutualisms. So in some cases it could have positive welfare effects. I asked Claude about the specific strain used in the Debug program, and it reported that most of the welfare effects land on females, who are already just being killed. Of course, we don't know that much about measuring mosquito welfare, but at least in terms of survival, ability to find a mate (which correlates to locomotor and sensory performance), etc., this strain isn't bad. And if they use something that really harms the released males they won't outcompete the local males, which would drive up costs (because you have to release more mosquitoes to compensate).
The technique will result in a reduction in number of mosquitoes. It's not clear to me how other populations would respond to that - I'm not sure what competitors there are for mosquito resources. But if you think mosquitoes have bad lives this could be a good thing (or neutral if you have person-affecting leanings). The FAQ on the Debug page claims that in urban areas, because the mosquitoes are invasive, it will just be a "return to normal" -- but that ignores the fact that many other things have changed (reductions in native insect populations, for example). If it's true that this specific species doesn't make up a meaningful part of any other animal's diet the effect is likely to be small, but that sounds like something we don't really know (well-resolved urban food webs are rare). They might mean "no animal anybody in ecology especially cares about."
For many bugs, high mortality during captive rearing is common. That doesn't seem to be the case for mosquitoes -- survival rates in the 90s are reported in many captive colonies and mass die offs are unusual (according to this, thanks Claude). But the success rates for male mosquitoes in the Debug project is around 70%. The paper is fairly detailed on the rearing approach so someone with more mosquito expertise than I might be able to say more about welfare. Broadly, I'd still expect it's much better than wild mosquitoes -- they're fed, kept at comfortable temperatures, spared from predators, etc.
An interesting question long term would be how this affects pesticide use in urban areas. If most pesticide applications in cities aims at reducing mosquitoes, and we start using Wolbachia to control them instead, pesticide application might go down, resulting in recoveries of other insect populations and reduced sub-lethal harms. If you think bugs have good lives, yay. If you think they have awful ones, uh oh.

I'd likely support doing this -- effects on humans are good (which to be clear I weight very highly!), male mosquitoes seem broadly fine, and females are killed mostly as pupae, I'm clueless about the welfare interpretation of population effects. That said, others might feel more concerned about population effects, which probably depends a lot on how you feel about insects generally and how much you think this could alter insecticide usage.

I spent less than an hour on this comment though, so obviously this is not the final word!

mal_graham🔸

1mo*

I am not at all an expert in mosquitoes, but I think it would be hard to figure out more than the direct effects on mosquitoes, which are sex specific. A few assorted thoughts:

Scale: the Google Debug program website says when applied, they need to releases 100s of thousands to millions of mosquitoes each week, so the scale is reasonably high.
They release only male mosquitoes, but it's not possible to rear only male mosquitoes (AFAIK), so they are killing all the females. The Debug project's Nature Biotechnology article says that they sort males from females as pupae (which may involve low welfare cost, I don't know when sentience emerges in insects and especially whether it's possible to feel pain as a pupa), and again as adults (which, if insects are sentient, probably is painful for those females). They report that 95% of females are removed as pupae, so a much smaller amount are being killed as adults. About 2.5% of what make it through the first sort are females, so we can estimate that to achieve daily releases of ~ 75k males, ~2000 females are killed as adults daily. The paper does not seem to report how the females are killed for either pupae or adults, which is a big gap from a welfare perspective.
According to this, Wolbachia often shorten lifespans. But several strains also seem to enhance immune function and have other mutualisms. So in some cases it could have positive welfare effects. I asked Claude about the specific strain used in the Debug program, and it reported that most of the welfare effects land on females, who are already just being killed. Of course, we don't know that much about measuring mosquito welfare, but at least in terms of survival, ability to find a mate (which correlates to locomotor and sensory performance), etc., this strain isn't bad. And if they use something that really harms the released males they won't outcompete the local males, which would drive up costs (because you have to release more mosquitoes to compensate).
The technique will result in a reduction in number of mosquitoes. It's not clear to me how other populations would respond to that - I'm not sure what competitors there are for mosquito resources. But if you think mosquitoes have bad lives this could be a good thing (or neutral if you have person-affecting leanings). The FAQ on the Debug page claims that in urban areas, because the mosquitoes are invasive, it will just be a "return to normal" -- but that ignores the fact that many other things have changed (reductions in native insect populations, for example). If it's true that this specific species doesn't make up a meaningful part of any other animal's diet the effect is likely to be small, but that sounds like something we don't really know (well-resolved urban food webs are rare). They might mean "no animal anybody in ecology especially cares about."
For many bugs, high mortality during captive rearing is common. That doesn't seem to be the case for mosquitoes -- survival rates in the 90s are reported in many captive colonies and mass die offs are unusual (according to this, thanks Claude). But the success rates for male mosquitoes in the Debug project is around 70%. The paper is fairly detailed on the rearing approach so someone with more mosquito expertise than I might be able to say more about welfare. Broadly, I'd still expect it's much better than wild mosquitoes -- they're fed, kept at comfortable temperatures, spared from predators, etc.
An interesting question long term would be how this affects pesticide use in urban areas. If most pesticide applications in cities aims at reducing mosquitoes, and we start using Wolbachia to control them instead, pesticide application might go down, resulting in recoveries of other insect populations and reduced sub-lethal harms. If you think bugs have good lives, yay. If you think they have awful ones, uh oh.