Virus and bacteria tag team against parasitic wasp

Th pea aphid is a lucky little insect. It may be the target of parasitic wasps, but it has protection, in the form of a bacteria called Hamitonella defensa.

But the bacteria only protects the aphid if it is itself infected by a bacteriophage virus called APSE (which is short for A.pisum secondary endosymbiont”).

The phage bestows protective powers on the bacteria thanks to a single gene that encodes a toxic protein. It also makes a lot of it – the toxin-producing gene is almost three times as active as one of the most active genes in the bacterium’s own genome.

How exactly this poison kills the wasp is unclear and it’s worth noting that H.defensa‘s has toxins of its own. The most intriguing possibility is that somehow the viral and bacterial poisons work together to kill the wasp, but that’s a theory to be tested in the future. [Not Exactly Rocket Science]

The parasitic wap in question is called Aphidus ervi and is a nasty lil’ fella. While its not really a parasite itself; its an exoparasitoid, meaning it doesn’t itself infect a host, but use the host to lay its eggs in.

This means that that the poor host, an aphid perhaps, and as soon as the larvae hatch they will start eating the aphid alive from the inside out.

Nasty, indeed.


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