the use of pesticides on crops has been a common farming practice for decades. what had been the greatest effect of natural selection through the use of pesticides on certain insect populations?

Either genetic frequency or genetic drift . genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time; genetic frequency is an allele that’s defined as the total number of copies of that allele in the population divided by the total number of copies of all alleles of the gene. HOPE THIS HELPS!!!