"The complex adaptive nature of ecosystems means that evolutionary forces are strongest at lower levels of organization; we have learned that the hard way in our continual battles with the evolution of resistance to pesticides and antibiotics, and the unwillingness of [insects and] microorganisms to take a reasonable approach to making things easy for us (Levin 2001, p. 17) "
Whether you believe in conventional "evolution" theories or not is, in this case, arbitrary. The fact is, insects are, and have been since the insecticide glory days of the 1940-1950's continually adapting and evolving to become more resistant to pesticides and insecticides. How does this happen? Every time a chemical substance is sprayed in a effort to kill weeds or insects, a few naturally resistant members survive. As these surviving members reproduce, their off-spring subsequently carry the chemical-resistant genes. Because insects have the ability to reproduce very rapidly (within a single year multiple generations can come in to existence) the genetics that allow for that specific chemical resistance become the majority within the population. Eventually, even high doses of such chemicals will be rendered useless.
Why is this important? Because these same insects are the ones ravaging vegetable fields and causing detrimental yield loss for farmers. Beginning in the 1940's, farmers in the U.S lost about 7% of their crops to pests. That number climbed steadily in the 1980's to about 13%. Today, in parts of the U.S up to 60% of crops have been lost due to insecticide-resistant pests.
For this reason, IPM (Integrated Pest Management) and biological control are crucial practices in horticulture and vegetable crop production. These practices focus on more "creative" green ways of approaching insect management. Take Diatomaceous Earth as an example. Diatomaceous Earth (when purchased appears as a powder substance) is fossilized silica; a micro-organism marine algae. On a microscopic level, diatoms appear as fragmented, shattered glass particles. When insects like ants and beetles which possess an exoskeleton to aid in, among other functions, water retention walk or crawl over diatomaceous earth they soon find themselves spliced and splintered. The effect would be similar to a tire running over police road-spikes. Yea….
Grits, yes the edible kind, are another 'green' way of approaching pest infestation. When dry, grits can be consumed by small insects (everyone likes grits, right!). But once in the stomach, the grits begin to expand and eventually…POP!
Biological control is the use of a specifically chosen living organism to control a particular pest. This chosen organism might be a predator, parasite, parasitoid, herbivore or a disease that attacks the harmful insect. For example, parasitoid wasps and flies lay their eggs within a host insect. Eventually the immature development will kill the host. Unlike many insecticides, most biological controls are insect-specific which result in less environmental hazards. And unlike insecticides, a tolerance or immunity cannot be established, as the effects target the physical state of insects, not the genetic make-up.
It is important to note that biological control agents do not completely eradicate an infected area of the pest, as that would lead to starvation; but rather the agents reduce the population of insects to such that they are no longer a threat to the crops.
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