Reversing Insecticide Resistance Using CRISPR

 

Researchers have tested using CRISPR to reduce insecticide resistance in pests. In simple form, this was done by editing the gene which controls insecticide resistance by returning it to a wild type allele, making it susceptible to insecticides. This obviously came with ethical concern so the researchers only made it a temporary solution. Hence, why they returned the gene to wildtype rather than removing the insecticide-resistant variant genes entirely by replacing them with susceptibility to pesticide genes. They term for this is a e-Drive cassette which spreads through CRISPR gene editing which binds to Cas9 DNA and cuts out voltage gated sodium ion channel (vgsc) insecticide resistant gene site. This solution is not permanent since removing insecticide resistance lowers fitness of pests.

What the e-Drive essentially does is disable the insecticide resistance gene by using CRISPR to ensure that the wild-type gene has a 100% frequency of being passed to offspring. Since the non-resistance gene is being spread rapidly, it can spread faster than the resistance gene within just a few generations, 8 to 10 to be specific. Although the cassette was also inserted with a fitness check which limits viability or fertility. So the wild type gene spreads, increasing susceptibility and reducing pests (for example on crops), then over time the added fitness check along with the natural lower fitness takes over and the non-resistant pests eventually die out. The population returns to a normal resistant one. The beauty of this e-Drive cassette is that it can be reintroduced whenever needed, for example, if the pest problems become large again, then the e-Drive can easily be added back. It is a short term, effective, easily implemented, and easily removed strategy that the researchers hope could also work on mosquitos for malaria.

This is a great development because insecticide-resistance is rapidly spreading throughout populations of pests. While we need to control pests from destroying things like crops, it is becoming increasingly difficult to use pesticides to kill them. We also do not want the e-Drive to become out of control which could seriously harm pest populations. As the researcher says, this strategy will work without creating any other perturbation to the environment. If we can successfully increase pesticide effectiveness without entirely harming a pest population, I am all for it.

Links

https://www.sciencedaily.com/releases/2024/11/241122172740.htm

https://www.epa.gov/pesticide-registration/slowing-and-combating-pest-resistance-pesticides

A plant gene may have helped whiteflies become a major pest

 

In this article written by Jonathan Lambert, a gene has been found to let insects neutralize the toxins found in plants commonly used for defense. This gene was first found 35-80 million years ago when a whitefly landed on a plant and somehow the gene made its way to the whiteflies genome. The gene then allowed the whiteflies to feed on flora. Ten or 20 years ago, many scientists thought that gene swapping wasn't possible and that a gene had to overcome many barriers in order to move from plant to insect. Now, we know that gene swapping is common and can occasionally happen between a plant and insect. This process is known as a horizontal gene transfer.

Researchers were able to determine that the gene is BtPMaT1. They think that this gene either came from a common ancestor of both plants and insects or that whiteflies somehow acquired the gene from plants. A study was done where RNA was inserted into tomato plants and they were later ingested by whiteflies. The RNA was made to disable the BtPMaT1 gene and after a week of feeding on altered plants 2,5000 whiteflies were dead. These effects suggest that the BtPMaT1 plays an important role in helping whiteflies go through plant defenses. 

I think that its crazy that whiteflies somehow acquired this gene from plants and can know use it to get through plant defenses. I hope more research is done on other insects or animals to see if maybe they have the gene as well. I also really liked how the study showed just how important the gene has become to whiteflies. I have also attached an article that looks at the genes more closely.

Links:

https://www.sciencenews.org/article/whitefly-plant-gene-transfer-pest-biology-chemical-toxin

https://www.theatlantic.com/science/archive/2021/03/whiteflies-gene-transfer/618407/