Disease Vectors and Pests: How Genetically Modified Insects Could Affect the World

Featured Image Caption: There are more than 500 million cases of mosquito-borne diseases every year. So it’s no surprise that one of the organisms that have had their genes modified are mosquitoes, helping reduce their reproduction rate and the spread of diseases. (Image Source: “mosquitoes” by Department of Foreign Affairs and Trade, licensed under CC BY 2.0).

Reference: Devos, Y., Mumford, J., Bonsall, M., Camargo, A., Firbank, L., & Glandorf, D. et al. (2022). Potential use of gene drive modified insects against disease vectors, agricultural pests and invasive species poses new challenges for risk assessment. Critical Reviews In Biotechnology, 42(2), 254-270. https://doi.org/10.1080/07388551.2021.1933891

Have you heard of genetically modified insects? Although it sounds like something taken out of a sci-fi movie, gene-modified insects aren’t radically changed mutants that will overrule the world. They are actually normal insects that have been slightly modified so they aren’t able to reproduce or spread a specific disease or pest as effectively or as quickly.

The prospect of genetically modifying insects to lessen the strength of disease crises is something scientists and health experts saw as a saving grace. Modifying a portion of insect populations like this could help control disease vectors and agricultural pests, posing some very important public benefits. But at what cost? Nobody is certain what the long-term effects of these modifications could have and how we can assess the risks against the benefits.

Why Modify the Genes of Insects?

Diseases that spread through animals tend to be highly contagious and hard to manage, especially if spread through fast-breeding animals (as is the case with most insects). So far, gene modification in insects has been used either to suppress the population or modify them.

Caption: CRISPR-Cas9 is one of the methods being used for genetic modification, as it’s fast and highly accurate. (Image Source: “CRISPR Cas9” by National Human Genome Research Institute, licensed under CC BY-NC 2.0).

Population suppression can be achieved by mutations that affect sex-specific survival, reduce offspring fertility, or lower the lifespan of all individuals. Population modification is used mostly for disease vector control. These mutations can affect disease survival and transmission within the individual by introducing genes that kill or block the reproduction of the pathogen inside the insect. That is to say, insects are being modified so they aren’t able to reproduce, survive, or spread disease, and therefore are less of a threat to human health and society.

What Are the Risks?

The truth is that we aren’t fully aware of the effects that these modifications could have on ecological relationships and the environment, but scientists have started to speculate about the outcomes that could branch out of meddling in the insects’ natural course.

One of the first concerns that arose was, what if the modification causes toxicity or induces allergies in humans? That is to say, despite fixing the problem of disease transmission, there may be unforeseen consequences to human health.

Another concern branching from population suppression is the possibility of disrupting ecosystem interactions. In other words, reducing the disease vector population could lead to the overpopulation (or crash) of another species that interacts or relies on the organism. As a result, we could see the rise of another disease vector, may that be for the same disease or perhaps even for another disease.

Then, there is always the possibility that the pathogen can become more virulent and still use the modified insect as a disease vector, potentially making it into a supervirus – viruses that have higher survivability towards medicines and other external factors.

And what if the genetic modification spreads, unintentionally, beyond the target population? This phenomenon is known as spillover and could cause unprecedented and incalculable damages.

So, What Now?

That is one complicated question that scientists are still assessing and debating. There is no denying that genetically modified insects could benefit us, as the prevalence of pests in agricultural systems and the incidence of diseases like dengue fever, malaria, chikungunya, and zika decrease. But what if this only pushes an onset of stronger pests and diseases? Or what if we unintentionally eradicate a species due to spillover? It is time to trust the wide, collaborative network of scientists and specialists that are invested in this area of science.

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Andrea Valcarcel

Having graduated with a Bachelor of Science degree in Animal Biology from Thompson Rivers University (BC, Canada), I am currently working as a marine mammal specialist and marine resource analyst in the Dominican Republic while also being an MSc candidate in Ecology and Environmental Sciences. My research so far has been mostly focused on corals and marine mammals, but I'm not completely set on being focused on marine sciences for the rest of my life. When not monitoring marine ecosystems, you can find me training therapy dogs and reading YA and fantasy novels. Twitter: @andreavalcar

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