How does evolution apply to the use of insecticides and antibiotics?
The changes in the environment brought about by antibiotics result in evolutionary changes in the genetic makeup of the bacteria.
The bacteria lose genetic material in order not be affected by the antibiotics. The Beak of the Finch page 260-262.
This is an example of adaptive evolution. Another examples is the blind fish of Death Valley. The fish have lost the genetic information for making eye tissue.
This is a counter example for Neo Darwinian evolution. The loss of information is not an example of Neo Darwinian evolution. Neo Darwinian evolution implies and requires an increase in information.
The development of antibiotic resistance is the result of an adaptation caused by the loss of genetic information. This is a type of evolution but not Neo Darwinian evolution.
Insecticides and antibiotics act respectively on populations of insects and bacteria to check growth in number. Both are harmful chemicals and are able to kill living organisms. Application of both the chemicals, often ill-advised, has prompted evolution of resistant organisms.
An insecticide kills most of the insect pests when introduced in the field but some insects will definitely escape death after an exposure. Such insects are naturally resistant to the particular chemical insecticide. Hence in an artificially created environmental situation, the resistant ones become more successful: could be described as survival of the fittest.
Now as the population dwindles, i.e. in absence of most insect competitors, population of resistant organisms will flourish. Eventually the insecticide will fail to kill most insects as their population becomes resistant.
This is the reason why in today's world mosquitoes are all DDT resistant; but in 1940s Nobel prize was awarded to Paul Mueller for the discovery of the chemical: which was then described as highly efficient to control malaria!
The story is similar in case of injudicious use of antibiotics. World is now fighting against highly resistant super bugs. In case of bacteria, the condition becomes more serious as bacterial population evolves faster, and can directly acquire genes by transformation.
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