REGENTS QUESTION ON BIOLOGY!!! I need help on this difficult question, read it below.?

Question

Growers of fruit trees have always had problems with insects. Insects casue visible damage to fruits, making them less appealing to consumers. As a result of this damage, much of the fruit cannot be sold. Insecticides have been useful for controlling these insects, but, in recent years, some insecticides have been much less effective. In some cases, insecticides do nothing to stop the insect attacks. Idenify the original event that resulted in the evolution of insecticide resistance in some insects. PLEASE EXPLAIN HOW YOU GOT YOUR ANSWER. THANK YOU SO MUCH!!!!!!!!

Answer 1

I don't think your question is asking so much for a specific event as a general one which would cause the insects to be immune to the insecticide.

After an initial application of the insecticide, not all of the insects present may have been killed.  Maybe it rained, and the chemicals washed off, or the person who applied the chemicals didn't use enough, or the insects may have been more tolerant of that chemical.  The insects that survived the first exposure to the chemical then bred and passed on that resistance to their offspring, and through continued insecticide applications that would kill the weaker insects, the ones that survived were the ones who could resist the chemicals best.

A similar event is happening with bacteria that are becoming resistant to antibiotics - from antibacterial handsoaps and cleaners, and use of prescription drugs for less than the full time the drugs are prescribed or to treat conditions not caused by bacteria (colds are caused by viruses, and antibiotics don't affect them).  Sure, these may kill 99.9% of all germs, but the 0.1% that survive REPRODUCE and their "offspring" are also resistant to antibiotics.