Sunday, July 30, 2017

Let's control the fruit fly (Dacus spp): cosmopolitan pest of fruits and vegetables

Dr Abe V Rotor


Fruit fly (Dacus dorsalis (Family Tephritidae, Order Diptera) on banana and mabolo. Note the nature of damage, and size of the mature insect.

Old folks used to tell us kids in our time that the first rain in summer brings in the dangaw (Ilk) or fruit fly rendering native fruits, like duhat, macopa and guava, unfit to eat. True enough the first bite reveals tiny punctures, and when fully ripe. tunnels with tiny maggots squirming and catapulting to our disgust. We would throw away the whole fruit, and spit what we had hastily eaten.

But in those days the fruit fly had few hosts, until new varieties were developed and introduced. These became readily vulnerable, triggering the buildup and spread of the pest. New frontiers were opened, more kinds of crops cultivted, more varied agricultural practices developed breaking away from the natural cycle of the environment. Today the fruit fly has become a cosmopolitan pest of orchard, garden and field crops.

What a havoc the fruit fly can create on a mango tree laden with fruits. Or macopa in season. Guava. Caimito and the like. Orchards and plantations are ruined by this pest, a direct relative of the housefly.

And that's just part of a larger ruin. Trellises of ampalaya, squash, cucumber, and fields of pepper, tomato, eggplant, and other vegetables virtually go to waste.

Unless heavy doses of insecticide are applied - poison that coats whole fruits to repel the gravid female from laying eggs, poison to cover whole fields so that no place is left to harbor the pest for a second round of attack. And poison that can penetrate the ensconced maggots before it could do further damage. This is the most potent pesticide ever formulated. It is systemic poison because it circulated through the plant sap, like blood, and any insect that attacks from the inside or outside is certain to die.

It is a fact that poisons in food, air and many items cause cancer. Pesticides are culprits to many cases of cancer. So with kidney and liver problems, fatal or lifelong liability. Pesticides being mainly nerve poisons affect the brain and the senses, and therefore behavior and quality of life in general.

We relate the issue of pest to global warming which has disturbed our climatic pattern and modified geography. Rainfall has become erratic, Seasons unsuspectingly come early or late. Sometimes there is summer. Force majeure is more often and severe. Thus the need of new agricultural strategies.

Now we have greenhouses of tomato, melon, bell pepper, but greenhouse products are more expensive than those produced on open fields. Geneticists came up with Genetically Modified crops - like FlavrSavr tomato.Genetically modified organisms or GMOs are dangerous to health and human development, particularly among children. That is why GMOs are branded Frankenfoods (from Frankenstein, the man-made monster in Mary Shelley's novel of the same title.)

The fruit fly is not merely a pest. It is an element that has sown destruction to agriculture, and therefore to the economy. It is changing the way we live. Let's control it before it does more harm.

Let's control the fruit fly (not to be mistaken for the Drosphilla melanogaster), that has evolved into several species under the genera Bactrocera, Dacus and Ceratitis. They have become major pest worldwide of orchards, farms and garden, on avocado, banana, citrus, cacao, coffee, cucumber, guava, papaya, pepper, eggplant, tomato, melon, cucumber, and a host of other plants - not to mention the most important host, the mango.

Let's control the fruit fly by cutting off its life cycle, before it lays eggs on fruits - young and ripe - that ultimately causes them to fall or rot on the tree; and in its feeding introduces bacteria and fungi that exacerbate damage to the tree and plantation, not to mention the harmful effect it has to humans. That by keeping strict sanitation, collecting damaged fruits as possible breeding material, and eliminating alternate hosts to bridge the next season, its population can be kept on a safe level.
Let's control the fruit fly by bagging the fruits early with paper bag, cut newspaper, and other suitable materials, before the gravid female oviposits on the fruits, popular a practice on mango, nangka, cucumber, ampalaya, and other crops that are convenient to protect in this laborious means. Bagging also protects fruits from other pest, injury, excessive sunlight, and reduces blemishes and deformities.

Let's control the fruit fly by prudent use of chemical pesticide, applying it only as a last resort after all safer means are exhausted, and applying only at a threshold level determined collectively by growers in the area. Overuse of chemicals have spawned mutants in the pest population leading to increased resistance among survivors which they pass on to the next generation. Thus higher dosage or more potent chemicals are required in succeeding seasons. ------------

Let's control the fruit fly through cooperative farming, following specific schedules of planting, cultivation, and harvesting, among other cultural practices, like crop diversification, use of resistant varieties, roughing affected plants and residues and burning them. Quarantine control is easier to implement, so with other government rules, and specifications of products for the local and foreign markets.

Let's control the fruit fly to bring down the price of fruits and vegetables at affordable level, assure quality products and reduce crop loss, increase income of producers and processors, and reduce dependence on imported fruits and vegetables. And encourage backyard self-sufficiency, promote proper nutrition and good health.

Let's control fruit flies with the same resolve in suppressing global scourges of crops (tungro of rice, blight of cereals, borers of corn), and livestock (foot-and-mouth disease, mad cow disease), epidemics affecting human populations (HIV-AIDS, Ebola, Avian Flu), through personal initiative and or in support to national and international organizations. And through research and extension, through the academe and R and D institutions.~




Cucurbit fruit fly (Dacus cucurbitae), representation of a typical fruit fly (Dacus sp); baiting fruit flies with diluted vinegar in plastic bottle with punched holes to let attracted fruit flies to enter and get trapped), bagging of green mango fruits. Acknowledgment: Internet www infonet-biovision.org

No comments: