What can happen if a pesticide is used on an insect population but only kills 98% of insects

Answer:

It can make the resistant insect live and to produce more insects through reproduction.  This will happen if a pesticide is used on an insect population but only kills 98% of insects

Explanation:

Pesticides are chemicals used to kill the population of insects attacking the crops plants and household things. 98% of insects are killed by pesticides because they do not have the gene of resistance which disables them to survive. Some of the insects have resistant genes which helps them in surviving and reproducing more insects.

The number of these insects’ increases through reproduction. Some will be pesticides of "contact" that kill when the organism falls into direct interaction.  Some are "systemic" and it will be embedded into the molecular structure of a plant. Once they bite the crop, they destroy them and consume the chemical pesticide.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.