Invertebrate Welfare — May 2021
This month: a deep dive into new RNAi insecticides, insect farming, and more.
RNAi insecticides: a major development in agricultural insecticide use
Why should you care about insecticides use?
Starting from a US-based estimate of the number of insects killed by insecticides (produced by WIld Animal Initiative) I estimated that somewhere between 100 trillion and 10 quadrillion insects are killed annually by insecticides, although my approach was fairly inexact.
This estimate suggests that insecticide use represents the single largest direct, human-caused, source of non-microscopic animal death in the world, by number of individual animals killed.
The “non-microscopic” caveat excludes nematodes and other very small animals (sorry nematodes!). These animals are so ubiquitous, tiny, and numerous that it’s really difficult to put together any kind of estimate.
As a scale reference/sign of how little attention we pay these creatures: at time of writing I can buy 50 million nematodes for $46 USD on Amazon.
If 1 quadrillion insects are killed by insecticides annually, and each death involves 10 seconds of pain, then every year, insecticides cause 317 million years of insect suffering.
These figures are totally made up, but I think it is relatively conservative: some insecticides are intentionally very slow acting (although most agricultural insecticides do kill more quickly). Insecticides are, however, very complicated to analyze from a consequentialist perspective. The insects killed by insecticides would eventually have died anyway, and it’s unclear how to value the lost time of their lives. And, if insecticides reduce overall insect populations, the number of insect deaths overall may be lower when insecticides are applied.
That being said, many of these complexities can be reduced if a particularly painful insecticide is swapped with an equally effective, less painful alternative -- an approach that seems robustly positive.
Given that it might be relatively easy to easily improve the lives of millions of animals through insecticide-related interventions, improving insecticides seems like a promising area for future animal advocacy work. And RNAi insecticides seem to be the next frontier for insecticides.
What are RNAi insecticides?
RNA interference (RNAi) insecticides, or gene-silencing insecticides, are a relatively new approach to insect management, and were developed in 2006.
The theoretical promise of RNAi insecticides is that they can target a single species of animal, dramatically reducing the number of deaths caused by insecticides.
These insecticides work by introducing RNA to an area that prevents a specific protein from being produced in a specific species of insect. This results in the death of that insect.
Since the insecticide blocks only specific messenger RNA, they can be targeted to specific nucleotide sequences found in only one species of insect.
Since most insecticides used today kill many species of animal, including those that do not actually damage crops, more selective agents like RNAi insecticides would likely reduce the overall number of insect deaths due to direct human action.
RNAi insecticides have been called a key to “A new green revolution.”
The two factors that make RNAi insecticides so promising are their comparatively low environmental footprint, and the possibility that they could easily resolve issues of increasing insecticide resistance in insect populations.
The environmental promise of RNAi insecticides is due to the decrease in non-target, non-pest death that would come from their application. For example, pollinator declines have been attributed in part to insecticide use, but these animals are not considered pests. RNAi insecticides could prevent insecticides’ contributions to these declines.
Insecticide resistance has become an area of increasing concern in the agricultural community, with major pests such as the corn rootworm becoming resistant to several families of insecticides, making pest management more and more difficult.
While insecticides probably get a bad rap in many people’s minds, their impact on the world shouldn’t be understated. The Green Revolution, during which modern agricultural methods, many modern insecticides, and insect-resistant crops were developed, saved millions of human infants from early mortality annually, and has likely prevented over 100 million human infant deaths from food insecurity over the last several decades.
This isn’t to say that the future of agriculture must involve insecticide use. But if we were to transition away from insecticides too rapidly, we might cause millions of additional deaths. It’s hard to wrap one’s mind around the food and crop loss that is prevented by insecticides, but the scale is massive.
It’s worth noting that insects resistant to RNAi insecticides might develop in time as well. Because creating new RNAi insecticides is relatively cheap, resistance to specific chemicals can be evaded by developing new products. But some insects have already been shown to develop resistance to the entire technique.
The main takeaway: RNAi insecticides, if they prove to be viable, will cause a huge shift in our approach to agriculture, and will have a massive impact on insect lives.
That could be a big if: while commercialized RNAi insecticides are available or in development for several species, environmental organizations have already begun campaigning against them on the grounds that they are intentional genetic modifications of animals with unknown consequences.
There are always some risk associated with using a new insecticide, but for RNAi products in particular, there is some evidence that they can accidentally target the wrong gene, which would carry some risk of affecting non-target animals. Additional technological progress could reduce this problem; but whether it convinces the environmental groups remains to be seen.
What are the implications of RNAi insecticides on invertebrate welfare?
The primary considerations for assessing a change in insecticides are: does it change how much affected animals suffer, and does it change how many individuals suffer?
If this change does change which individuals are killed, a further question to analyze is whether newly affected or newly unaffected animals are better or worse off for the change.
I was able to find some information to address the first question: does it change how much affected animals suffer?
One study in Colorado potato beetles found that there was a fairly minimal reduction in crop destruction in the first 24 hours after treatment, but a larger reduction between 24 and 48 hours. This suggests that RNAi insecticides take at least 24 hours in this species to kill or severely injure insects. This appears to be significantly longer than most conventional pesticides.
RNAi insecticides function typically by silencing a gene necessary for cell division, so the insect can no longer do cell division, or some other essential process.
It’s unclear to me how painful a decrease in cell division would be. It seems likely that pain would be caused by the failure of basic bodily functions that require cell division. Chemotherapy also works by stopping cell division, and seems to be very painful, but it’s unclear to me if that’s from other effects from the drugs.
Based on the duration and mechanism of action, it seems reasonably likely that RNAi insecticides cause as much or more suffering as many other common insecticides — they are at least not obviously better.
However, on the question of what happens to the non-target animals who otherwise would be killed (by a standard insecticide), the jury is still out — at least until we have more data on frequency of different causes of death among invertebrates.
Even if they have non-target effects, RNAi insecticides will almost certainly dramatically reduce the number of insects killed directly by humans, so much of the question of their impact on welfare will be how this change impacts insects that these new insecticides do not kill.
Insect farmed for food
Yellow mealworms have been approved as human food in the EU, the first insect to secure this approval.
Notably, while this might be a first step to more insect-based human foods, the insect farming industry is primarily focusing on raising insects to feed animals, especially fish.
This is likely good news for French company Ynsect, one of the largest insect producers in the world, and the largest mealworm producer in the world.
Currently, there are 11 other pending applications for various insect species to be approved for human consumption under Novel Food Regulations in the EU.
There are even more regulations under consideration outside the scope of this regulatory body, such as a proposal to feed various animals, including insects, to other non-ruminant animals. This proposal received significant public pushback from animal advocacy organizations last month.
Brexit is causing major issues for the UK’s edible insect industry.
Apparently, transitional regulations that allowed the production of insects in the EU were not included in legislation that was passed into UK law as part of the transition, and the legal status of these facilities is unclear.
UK companies also received significant public funding from the EU.
The UK’s Food Standards Agency is currently reviewing whether or not to pass on the transitional regulations into the UK, so this issue may be resolved in the near future. Until then, the UK’s insect production is in a legally ambiguous territory.
Miscellaneous links
A new book on wasps joins the growing genre of pop science profiles of insect species. Last year a similarly prominent book on termites was published. Maybe these will offset the decline of insect representation in biology textbooks.
Apparently some people are eating the Brood X cicadas that emerged across the East Coast of the US this weekend.
The first genetically modified mosquitoes released in the US (in Florida by company Oxitec) are now hatching.
Harvard Law School’s Animal Law and Policy Clinic is petitioning the National Institutes of Health to consider octopi and other cephalopods as animals and for them to be fully protected by animal cruelty regulations that protect vertebrate animals in federally funded research.
The new Animal Welfare (Sentience) Bill introduced in the UK parliament does not explicitly include invertebrates, but does include a provision that allows them to become covered by future amendments. Dr. Jonathan Birth argued in The Guardian that evidence may arise that will strengthen the case for these amendments.