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As suggested in this article, the evolution of the adaptive immune system didn't actually give vertebrates a huge benefit, it just led to an escalation of the arms race between vertebrates and pathogens. As a result, we cannot survive without an adaptive immune system anymore.

One can then ask what would happen if we were to create bio-engineered insects with an adaptive immune system in the lab. If a similar escalation between the pathogens and the immune system would take place, then ordinary insects outside the lab would also be affected. But these ordinary insects would not be able to evolve an adaptive immune system before being wiped out. So, it seems to me that all invertebrates, except those we keep in the lab would die.

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    $\begingroup$ No. Adaptive immune system does help only when an organism meets infection for the second time. It provides no help if there is no immunity yet. For short-living insects, developing long-term immunity does not provide much benefit. After the first wave of infection, a second generation of naturally-selected insects would have innate immune system well suited to combat subsequent waves of the same infection. $\endgroup$ – Alexander Aug 21 '17 at 23:18
  • $\begingroup$ What is the goal of your question and/or story? If you're simply asking if, from an evolutionary point of view, modified insects would win out over unmodified insects, the generic answer is, all other things being equal (thanks Occam!), absolutely... Except for Khan Noonien Singh... but maybe there simply weren't enough of the enhanced humans (thank goodness!). $\endgroup$ – JBH Aug 22 '17 at 1:54
  • $\begingroup$ @JBH It seems to me that merely creating modified insects in the lab and keeping them there would lead to disaster for the other insects, because the pathogens would evolve to adapt to the modified insects, making it impossible to survive with only an innate immune system. $\endgroup$ – Count Iblis Aug 22 '17 at 2:47
  • $\begingroup$ Only in the lab. I doubt the pathogens would spread since most diseases aren't airborne for long distances. $\endgroup$ – Bellerophon Aug 22 '17 at 8:25
  • $\begingroup$ @Count Iblis - pathogens would adapt to modified insects. For the original insects, new pathogens would not be necessarily more lethal. $\endgroup$ – Alexander Aug 22 '17 at 16:50
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I have several doubts about trustworthy of linked article, but let's take it for its face value.

Your plan is:

  • somehow induce creation if an adaptive immune system in a bunch of insects kept in captivity.
  • subject those to all possible pathogens available.
  • wait for them to develop resistance to pathogens.
  • wait for pathogens to learn how to overcome defenses.
  • release "enhanced" pathogens in the wild.

Do I get it right?

If so (otherwise, please, clarify):

  • I doubt a complex system like our own immune would fit in an insect, but let's assume it can be done.
  • "enhanced" pathogens may be able to circumvent defenses, but this does not mean they would be more dangerous than "normal" ones to "unprotected" insect population.
  • Insect do have an immune system, that is pre-charged (does not learn from surroundings) essentially because the do not need one: their reproductive cycle is short enough that successive generations adapt to pathogens.
  • When you release (worldwide? how?) your insect killer disease you'll stimulate insects to evolve and, after an initial hit successive generations will exhibit "innate" resistance for new pathogen.
  • All you would be doing is playing with fire and risk producing pathogens harmful to other species (including humans).

Bottom line: insect do not need to have an Immune System that learns in their lifespan because it is too short; their immune system learns in generations, but it's as efficient as ours.

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