[cogitator]

If in fact, it is ineffective, it is reasonable to expect that going back to its use and finding it useless, people will stop using it.

However, they may continue to use it for awhile in the mistaken belief that it is still effective (when it isn't), and using it when it is ineffective makes it worse than useless. I.e., using it when it is ineffective increases the development of resistance in target populations.

[Publius6961]

However, they may continue to use it for awhile in the mistaken belief that it is still effective (when it isn't), and using it when it is ineffective makes it worse than useless. I.e., using it when it is ineffective increases the development of resistance in target populations.

That is sophistry, pure and simple, and defies common sense.
If DDT is effective, the results and either immediate or evidebt in the short term.
If it promotes further resistance, as in selective survival of the fittest, it is long term. if there is a relationship between the two it is a manufactured one.