>In 1997, the last year for which global data was available, over 5.5 million pounds of the pesticide fumigant methyl bromide were applied to tobacco fields worldwide.

A few tobacco plants in isolation are going to be protected from insects easily developing a resistance to their natural defenses. We've been growing tobacco plants in massively concentrated fields for 400 years in this country. Nicotine is still a useful insecticide, just as Penicillin is still useful antibiotic.

Bar the tobacco beetle, I presume.