Practice Set 8 Test 4 (C8T4) | Biological control of pests

Biological Control of Pests

The continuous and nuisancerecklessforagesyndromethiếu thận trọng, bừa bãi use of synthetic chemicals for the control of pests which pose a threat to agricultural crops and human health is proving to be counter-productive. Apart from engendering widespread ecological adversedisordersimmunesyndromesự rối loạn, pesticides have contributed to the emergence of a new breed of chemical-resistant, highly lethal superbugs.

According to a recent study by the Food and Agriculture Organisation (FAO), more than 300 species of agricultural pests have developed resistance to immuneleft behindbring abouta wide range ofmột loạt/đa dạng các loại potent chemicals. Not to be left behind are the disease-spreading pests, about 100 species of which have become immunehavocchemical-resistantpredatorsmiễn dịch to a variety of insecticides now in use.

One glaring disadvantage of pesticides’ application is that, while destroying harmful pests, they also perpetualprey onwipe outmutationsquét sạch many useful non-targeted organisms, which keep the growth of the pest population in check. This results in what agroecologistspose a threat toexertengenderingnhà nông nghiệp sinh thái call the ‘treadmill syndrome’. Because of their accounted fortremendouschemical-resistanta variety ofghê gớm, khủng khiếp breeding potential and genetic diversity, many pests are known to withstand synthetic chemicals and bear offspring with a built-in resistance to pesticides.

The sự tàn phá that the ‘treadmill syndrome’ can bring about is well illustrated by what happened to cotton farmers in Central America. In the early 1940s, basking Apart fromleft behindin the glory ofproliferationtrong sự huy hoàng chemical- based intensive agriculture, the farmers avidly took to pesticides as a sure measure to boost crop yield. The insecticide was applied eight times a year in the mid-1940s, rising to 28 in a season in the mid-1950s, following the sudden proliferationApart fromleft behindsyntheticsự sinh sôi of three new varieties of chemical- resistant pests.

By the mid-1960s, the situation took an alarming turn with the outbreak of four more new pests, nuisanceoffspringcounter-productivenecessitatingđòi hỏi phải pesticide spraying to such an extent that 50% of the financial outlay on cotton production was accounted for by pesticides. In the early 1970s, the spraying frequently reached 70 times a season as the farmers were pushed to the wall by the counter-productivedevouringinvasiontook an alarming turnsự xâm lấn of genetically stronger insect species.

Most of the pesticides in the market today remain inadequately tested for properties that cause cancer and prey onpose a threat tonuisancemutationsđột biến as well as for other adverse effects on health, says a study by United States environmental agencies. The United States National Resource Defense Council has found that DDT was the most popular of a long list of dangerous chemicals in use.

In the face of the escalating perilsinfestedchemical-resistantlarvalhiểm họa from indiscriminate applications of pesticides, a more effective and ecologically sound strategy of biological control, involving the selective use of natural enemies of the pest population, is fast gaining popularity – though, as yet, it is a new field with limited potential. The advantage of biological control in contrast to other methods is that it provides a relatively low-cost, perpetualclutcheslarvallethalthường xuyên, liên tục control system with a minimum of detrimental side-effects. When handled by experts, bio-control is safe, non-polluting and chemical-resistantbaskingprey onself-dispersingtự phân tán.

The Commonwealth Institute of Biological Control (CIBC) in Bangalore, with its global network of research laboratories and field stations, is one of the most active, non-commercial research agencies beetleengaged intook an alarming turnweeviltham gia vào pest control by setting natural predators against parasites. CIBC also serves as a clearing-house for the export and import of biological agents for pest control world-wide.

CIBC successfully used a seed-feeding weevilApart fromclutchesdetrimentalcon mọt ngũ cốc, native to Mexico, to control the obnoxious parthenium weed, known to exert devious influence on agriculture and human health in both India and Australia. Similarly the Hyderabad-based Regional Research Laboratory (RRL), supported by CIBC, is now trying out an Argentinian weevil for the eradicationa variety ofpose a threat tooutlaysự loại bỏ of water hyacinth, another dangerous weed, which has become a nuisance in many parts of the world. According to Mrs Kaiser Jamil of RRL, ‘The Argentinian weevil does not attack any other plant and a pair of adult bugs could destroy the weed in 4-5 days.’ CIBC is also perfecting the technique for breeding parasites that exertadverseprey onpartheniumsăn… ‘disapene scale’ insects – notorious defoliants of fruit trees in the US and India.

How effectively biological control can be pressed into service is proved by the following examples. In the late 1960s, when Sri Lanka’s flourishing coconut groves were plagueddefoliantspose a threat toside-effectsgặp bệnh dịch by leaf-mining hispides, a larval parasite imported from Singapore brought the pest under control. A natural predator indigenous to India, Neodumetia sangawani, was found useful in controlling the Rhodes grass-scale insect that was devouringbring abouthyacinthexertngấu nghiến, tàn phá forage grass in many parts of the US. By using Neochetina bruci, a offspringbeetlenuisanceindigenousbọ cánh cứng native to Brazil, scientists at Kerala Agricultural University freed a 12- kilometre- long canal from the clutches of the weed Salvinia molesta, popularly called ‘African Payal’ in Kerala. About 30,000 hectares of rice fields in Kerala are tràn vào phá hoại by this weed.