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Q:
the plants and fruits we eat everyday are full with pesticides and herbicides in their genes. If a farmer uses quimicos to make fruit fly infertil so, it will dessaperar in two generations... what do you think we are eating when we eat an apple treated geneticly with this chemical andnd pesticide?

A:Expert Answer

This particular technology is called the ‘Sterile Insect Technique’ or SIT. The SIT involves no chemical or genetic additions to the food. Instead, sterilizing insects means to modify them using radiation and release them to drive their populations down through massive infertility of males. It’s a method that’s effective while being environmentally safe, but it doesn’t work on all species of insects. Scientists from the academic, government and industrial spheres continue to work together to find these sorts of solutions.

 

So let’s explore SIT, because this topic involves a lot of cool science history!

 

SIT is actually an old technique, developed in the 1950s to fight the New World Screwworm. Screwworm was a fly which made its living by eating cattle from the inside out, usually entering through eggs laid in small cuts In the 1930s, entomologist Edward Knipling had noted that female Screwworm flies only mate once in their life. He hypothesized that if he could get them to mate with sterile males, then the females would only lay infertile eggs.

 

He knew, if his idea held out, that this would allow for the control of pests without the need for chemical insecticides. Elimination efforts began in the 1950s, and the pest was eliminated from the U.S. in 1982.

 

Although this technique was developed to fight screwworm, other pests had the same biological quirks. The Mediterranean fruit fly is a pest species which is known to infest well over 200 species of high-value crops. The fly is a good invader, using a mixture of biological and behavioral quirks to establish in nearly every climate around the globe. Its wide host range guarantees that it will become a problem wherever a pregnant female happens to land.

 

 

Medfly continues to be held at bay in the U.S., and elimination programs have started throughout North, Central and South America. Techniques continue to be refined and genetic engineering has been considered as a potential source of new traits.

 

The other part of this question revolves around what happens when we eat fruits and vegetables produced under medfly SIT programs, which is a natural next step for people to wonder about.

 

Medflies are sterilized using small amounts of radiation, which causes lots of random mutations in the DNA of developing sperm cells. The result is the accumulation of mutations which simply cause the DNA to not work properly in the next generation.

 

The females have not been irradiated, so each egg produced from this mating contains a small amount of radiation damaged DNA. In areas where these flies have been eliminated, like most of the US, it’s unlikely that any DNA from released flies has been consumed because males do not deposit anything under the fruit.

 

 

 

I feel like a lot of misconceptions about agriculture come from the fact that there are some very significant barriers to finding information online. Good information is often hidden figuratively behind a layer of jargon or literally hidden behind a paywall. Either way it can be extremely difficult for folks to access good information, and I hope I’ve been able to satisfy your curiosity on this topic.

 

I really like this topic, because of the history of SIT and because of how effectively scientists from so many sectors of the scientific community have collaborated on this. If you would like to know more, I would direct you to the Relax, I’m an Entomologist Facebook page, the Biology Fortified blog, the Genetic Literacy Project, and my blog Ask an Entomologist.

 

References

Franz, G. (2005). Genetic sexing strains in Mediterranean fruit fly, an example for other species amenable to large-scale rearing for the sterile insect technique. In Sterile Insect Technique (pp. 427-451). Springer Netherlands.

Malacrida, A. R., Gomulski, L. M., Bonizzoni, M., Bertin, S., Gasperi, G., & Guglielmino, C. R. (2007). Globalization and fruitfly invasion and expansion: the medfly paradigm. Genetica, 131(1), 1-9.

Myers, J. H., Savoie, A., & Randen, E. V. (1998). Eradication and pest management. Annual review of entomology, 43(1), 471-491.

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