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Wasps Turn Caterpillar Victims Into GMOs!

Sep 20, 2015 07:56 PM EDT
Ichneumonid wasp
(Photo : Key Biscayne National Park, Florida, Ichneumonidae; Anomaloninae)

Your corn crops are GMOs. Your sweet potatoes are GMOs. Your dog? Odds are that Fido is a GMO. Now however, researchers were surprised to learn that even caterpillars have been modified with foreign genetic information, and not by scientists. Wasps, it seems, like to 'play God' too.

That's at least according to a study recently published in the journal PLOS Genetics, which details how the genetic information naturally found in a virus touted by parasitic wasps can also be found hiding in the DNA of several common caterpillars.

To be clear, it was long known that the virus in question is an important tool for parasitic wasps, who lay their eggs directly into the living bodies of butterfly and moth larvae. Called bracoviruses, these diseases work to suppress a victim's immune system, disrupting the cellular supply lines for waging war against invasive wasp eggs. Free to grow unchecked, the wasp larvae eventually burst out of the caterpillar that hosts them, must like a horrific scene from the iconic film "Alien." (Scroll to read on...)

A moth caterpillar parasitised by wasps. The entire body of this victim has been eaten from the inside.
(Photo : Silvia Mecenero) A moth caterpillar parasitised by wasps. The entire body of this victim has been eaten from the inside.

Study author and biologist Jean-Michel Drezen, of François Rabelais University in Tours, France, has been studying this parasitic relationship for decades. With an improvement in DNA analysis technologies, he and his colleagues had hoped that analyzing a bracovirus on a genetic level would help them better understand the complex interplay between wasp, virus, and caterpillar.

However, what they discovered was extremely unexpected. Not only do bracoviruses use their own genetic information to disrupt cellular processes (which was expected), but those viruses also seemed to be carrying wasp DNA.

Put simply, Drezen witnessed wasp-specific genes hop from wasp to virus, and then, stunningly, into the DNA of a caterpillar host.

"I couldn't believe it," Drezen recently told Science Magazine. "We did not expect this at all."

What we're talking about here is a process called "horizontal gene transfer," where the genes of one species wind up in the DNA of a completely unrelated group. This is most commonly seen in bacteria and fungi, with the incredible wars waged by soil bacteria inspiring the modern genetic modification process. In fact, the same bacteria family that is widely used for lab-side GMO creation, called Agrobacterium, also happens to be a ubiquitous soil bacterium found all over the globe.

"The key strength of the study is it clearly demonstrates that [viruses] have been a source of horizontal gene transfer for some insects," wasp expert Michael Strand, of the University of Georgia, who was not involved in the study, told Science. (Scroll to read on...)

Parasitic wasp (Figitidae) egglaying in a hoverfly larva.
(Photo : Flickr: S. Rae) Parasitic wasp (Figitidae) egglaying in a hoverfly larva.

However, now knowing that it can occur, it's then safe to assume that it has occurred many-many times in the past; and that's exactly what Drezen set out to look for.

In an analysis of several species of moths and butterflies the researcher and his colleagues found sequences similar to a known segment of bracovirus DNA - one that wound up helping them resist the attacks of another viral group (baculoviruses) purely by chance! This was also confirmed lab-side with real specimens.

What does that mean? According to the study, this could indicate that at some point history, lucky victims of parasitic wasps actually survived attacks, reached adulthood, and reproduced. And thanks to their coincidental benefit, wasp and viral genes were left to persist for many generations to come.

In other words, a number of wasp and butterfly lineages are just more examples of naturally occurring GMOs.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

 - follow Brian on Twitter @BS_ButNoBS

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