Florida citrus farmers have been blanketing their orchards with pesticides in an attempt to eliminate the Asian Citrus Psyllid, an insect that caries a fatal citrus disease. But the campaign has had unintended consequences, namely the eradication of the natural predators of another citrus pest, the leafminer. According to the USDA Agricultural Research Service,
“The leafminer moth, Phyllocnistis citrella, forms channels as it feeds inside citrus leaves and, as a result, often makes the plant more susceptible to canker disease. Further exacerbating the leafminer problem is the spraying of more insecticide to combat another pest—the Asian citrus psyllid. The insecticide is killing off the leafminers’ natural enemies, allowing the pest to increase in numbers.”
The moral, in my opinion, is the same for both nature and the economy: don’t tinker with complex systems and avoid putting all your eggs in one basket, i.e. crop monocultures. Doing so is asking for “black swans” and catastrophic failure. As Nassim Taleb says, “counter-balance complexity with simplicity.” The race to layer insecticides on top of insecticides and then search for pheromonal solutions is too complex for my taste.