Wednesday, June 24, 2009

Part 2 - Biological Control of Pest

Ducks feed on golden kuhol which became a major pest of
They also feed on insects and weeds for which they
are important biological agents of pest control.

Abe V Rotor

It is a common practice to remove unsightly cobwebs. But come to think of it. We are destroying natural insect traps built by spiders. Inside warehouses spiders prey on weevils and moths that destroy grains and other commodities. So with mosquitoes and flies at some corners of the house. No radar system or other echolocation instruments can detect the fine web, which makes this indigenous trapping devise.

On plants stalk the preying mantis that snatches its victim with one deadly grasp. The spotted ladybug overruns a colony of aphids and has its fill, unless the red ants guarding the aphids come to the rescue. A nest of hantik up in the tree has an army by the thousands. They swarm on intruders and large preys such as caterpillars.

Under the microscope one could examine the unsuspecting Trichogramma. Mass culture and dispersal of this parasite wasp has benefited sugar and corn planters since its discovery in the fifties.

Bacillus thuringiensis or Bt, has become the most popular entomophagous bacterium against Lepidopterous pest which include rice stem borers and corn borers. Applied as inoculums, Bt can cause widespread epidemic on these pests on the field.

Practical Pest Control at Home

Here are pest control techniques you can adopt at home.

1. To control furniture weevil and moths destroying the felt and the wood of the piano, place a dozen well dried black pepper (do not crush) in the piano chamber near the pedals. Paminta is a good repellant and has a pleasant smell.

2. Coconut trees whose shoots are being destroyed by rhinoceros beetle (Oryctis rhinoceros) can be saved with ordinary sand. If the trees are low, sprinkle sand into the leaf axils. Sand contains silica that penetrates the conjunctiva, the soft part of the body where hard chitinous plates are joined.

3. Bean weevil destroying stored beans, especially mungo, can be control by mixing a little ash of rice hull (ipa’) with the same principle as in rhinoceros beetle.

4. To get rid of nematodes in the soil, incorporate chopped or ground exoskeleton (skin) of shrimps into the soil, preferably mixing it with compost. Chitinase is formed which dissolves the cover of the egg and the body of the organism. Use poultry dropping to reduce nematode population.

5. To control cucurbit fruit fly, cover the newly formed fruits of ampalaya and cucumber with paper bag. Bagging is also practiced on mango fruits. Use newspaper (1/8 of the broadsheet) or used paper, bond size. Roll the paper, two inches in diameter, insert the young fruit, fold at the top and staple. Bagged fruits are clean, smooth and light green. Export quality mangoes were individually bag on the tree.

6. To discourage goats in nibbling the trunk of trees, paint the base and trunk with manure slurry, preferably their own. To keep termites away from mud-plastered walls, use termite soil (anthill or punso).

7. Raise ducks to eat snail pest (golden kuhol) on the farm. Chicken and birds are natural insect predators.

8. An extra size mosquito net can be made into a mini greenhouse. Here you can raise vegetables without spraying. You can conduct your own experiments such as studying the life cycle of butterflies.

9. There are plants which have repellant properties. Plant them around the garden. Examples are lantana (Lantana camara), chrysanthemum, neem tree, eucalyptus, madre de cacao (Gliricida sepium), garlic, onions, and kinchai.

10. To scare birds that compete for feeds in poultry houses, recycle old balls, plastic containers, styro and the like, by painting them with two large scary eyes, imitating the “eyes” on the wings of butterflies and months. Hang them freely where birds frequent the area. To scare off birds in the field, dress up used mannequins. They are more effective than the T-scarecrow. Cassette tapes tied along the field borders produce sound that scare maya and other pests.

Insects as Food

One practical means of insect control is by gathering them to supplement nutrition. Gathering of insects for food is not only confined among primitive societies but is still one of the practical means of controlling insects. Anyone who has tasted camaro’ (sautéed mole cricket) would tell you it is no different from a crustacean. Well, insects and shrimps belong to the same phylum – Arthropoda.

Locust may destroy crops, but in a way bring food to its victims. During a swarm, locust is gathered by the sacks and sold for food and animal feeds. So with gamu-gamu (winged termites) at the onset of the rainy season, which is also the time of emergence of salagubang, another insect delicacy. Other food insects are the grubs of kapok beetle, eggs of hantik, larvae of honeybee and cheese maggots.

When is a pest a pest?

When we see an insect, instinct tells us to kill it. It should not be. A caterpillar is a plant eater, but the beautiful butterfly that emergence from it is harmless. In fact it is an efficient pollinator. Hantik ants make harvesting of fruits very inconvenient because of their bite and sting, but they guard the trees from destructive insects. Houseflies carry germs, but without them the earth would be filled with dead bodies of organisms. They are nature’s chief decomposers working hand in hand with bacteria. Termites may cause a house to fall, but without them the forest would be a litter of fallen trees.

It is natural to see leafhoppers on rice plants, aphids on corn, bugs in the soil, grasshopper on the meadow, borers on twigs, fruit flies on ripening fruits. These organisms live with us under one biosphere. And if the rule is for us to dominate them, for all we know they have been dominating the earth for millions of years, even before mankind was born.

There is no way to escape pesky creatures. Conflict arises where their populations overrun our crops, spoil or stored products, and threaten our health and welfare. We have set thresholds of co-existence. As long as they do not cross this line, I think it is all right to be living with them, to ponder at the beauty of their wings, the fire they carry, the song they make, the magnitude of numbers, or simply to marvel at the mystery of their existence.

Green pond frog

Preying mantis

Nest of hantik ants

Burning is a practical way of getting rid of insect pest.
Burning is however, generally discouraged because it
deprives the farm of valuable organic matter, feeds for
livestock, and materials for mulching and mushroom

Living with Nature in Our Times,by AV Rotor, UST Publishing House, Manila.


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