Wednesday, June 24, 2009
Part 1 - Practical And Safe Way of Controlling Pests
Dr Abe V Rotor
Entomology – the science of insects – is a subject I love to teach. But before I take up the subject of controlling insects, I would like to emphasize beforehand that insects in general are extremely useful to mankind and the environment. Contrary to what many people think our world could not be any better without insects.
We would be missing honey and silk, fruits and vegetables which insects pollinate, fish which feed on them, and the Monarch butterfly that meets us at the garden at sunrise.
On the other hand we detest the presence of their destructive kin: the cockroach that roams and spreads disease, ticks that spoil a dog’s lovely look, caterpillars that defoliate our favorite tree, or simply the buzzing of a mosquito that interrupts a good rest.
If these negative traits are not enough to take arms against these pests, think that the most ferocious animal on earth is not the lion but the mosquito. With the diseases mosquitoes carry they have brought unimagined deaths and sufferings to mankind. It is said that death due to mosquitoes alone surpasses that which all wars in history have caused. Their most prominent victim is Alexander the Great who died of malaria on the banks of the Tigris-Euphrates river.
So here are strategies of war against our insect enemies.
There is perhaps no substitute to natural resistance – that which is carried by the genes in a plant or animal - in combating a pest or disease, and in surviving under harsh environment. Where do these genes come from?
Even before scientists came to the conclusion that resistance (and also susceptibility) is hereditary, early farmers were already adopting the principle in plant breeding and animal husbandry, these being the foundation of the first green revolution that brought agriculture to its golden age in the last millennium.
It is evolution that brought desirable genes together in a species. “Survival of the fittest,” Darwin’s general formula is the gradual pooling of these genes through time, thousands if not millions of years. This also explains why varieties and breeds native to a place are more resistant than their introduced (non-indigenous) counterparts. Wittingly or not, man has caused the elimination of resistance genes, even as he chooses those that directly contribute to his economic welfare.
In order to gain from this knowledge, one may look into the adoption of these two measures.
1. Choose plants and animals that are genetically adapted to the place. They have the natural resistance to pests and diseases, as well as unfavorable conditions prevailing in the area.
2. Maintain physiologic resistance by enhancing soil nutrients and proper cultural practices. Healthy plants have less pest and disease problems. So with animals. This leads us to the next practical technology.
Proper Cultural Practices
If you see farmers planting and harvesting their fields at the same time, they are actually practicing a practical means of minimizing crop loss. Not only that the damage caused by a pest is spread out over the whole area, the insect’s life cycle is controlled, thus eliminating the possibility of pest and disease outbreak. There are of course other advantages of cooperative farming such as communal irrigation, mechanization, and collective marketing which are the answer to the problem on economics of scale.
A key to control pests is to eliminate their breeding places, such as uprooting infested plants, or pruning affected parts, then burn them. Plant trap crops ahead of planting time to attract the potential pest. The trap crop is then rouged and burn thus eliminating the threat. Eliminate weeds because they serve as alternate host. Now we understand why fields are left vacant after harvest and during summer. This allows the soil to rest, and to break the life cycle of pest and diseases.