The Lies of Rachel Carson

Research has not shown that. At least unless you think "quickly" means hundreds of thousands of generations at high ppm. Most insects learn about it and avoid it, giving them no chance to evolve immunity.
Additionally, any immunity is lost in a few dozen generations, which is more than enough for pathogen control.

Oh, and what the heck is "genetic immunity"? Immunity of genes to attack by viruses?

"Through natural selection"

What the heck? If you're applying DDT then it's artificial selection. I don't think your sources are any good.

Also, I will lol if this person claims they are a molecular biologist. If so, they are a pretty bad one. Glu-ST is known to metabolize DDT, pretty much every animal we know of can metabolize DDT (that's why it's so non-toxic), but they can never metabolize enough to be completely healthy.

KDR is actually harmful to the mosquito and the population loses that resistance through natural selection once you remove the artificial pressure (DDT).

There were guys who used to eat the stuff to demonstrate its basic harmlessness and at least one guy who fell into a vat of the stuff and is still walking around. Survivors of the Nazi death camps were all sprayed with the stuff from head to foot to kill lice and keep them all from dying of typhus.

I remember reading somewhere that DDT banning is also responsible for the rampant return of bed bugs.