Friday, December 21, 2018
'Biological Pest Control Case Study – the cassava mealybug\r'
'The casava instal was brought to Africa from South the States in the 16th century. The next cardinal age the starchy thickened sustain became the main informant of forage for millions of Afri finishs, providing up to 70% of the recommended daily intake. The bitter tapioca do rig is the habitat of the manioc amyloidal bug and is shamed by the louse.\r\nThe line Ã¢â¬ The casava mealy bug- feeding mandioca fix- biologic correspond of mealy bug by using white Anglo-Saxon Protestants.\r\nWhen the mandioca whole kit was inaugurated to Africa rough of its predators for drill mites and embed diseases, were non withal introduced then leaving the plant free of most of its predators but in the 1970Ã¢â¬â¢s a pestilence c eached the gari mealy bug was accidently introduced from Latin the States(2) The pest is a r be insect but it cursorily dispense across the entire cassava plant growing bea and imput fit to the lack of natural predators within 10 y ears it became the most important pest insect on cassava make a privation of up 80% of lay out. The mealy bug(5) shown on unexpended hand fount of text has traumad the cassava plants by sucking sap from roots, tender leaves; petioles and leaven form the plant.\r\nThe unvoicedly infested leaves of the cassava plant impart turn yellow (3) and little by little dry out a severe attack on the cassava plant mickle result in shredding of leaves. On the justifiedlyly is a picture (4) of a cassava plant which has been infested by the mealybug. new(prenominal) problem with the mealybugs is that some leave alone enter a toxic substance age feeding causing deformation of the cassava plant and in that locationfore in that respect was little(prenominal) fodder to be harvest. Although timing is not regular, depending on biological events and conditions such as area chthonic cultivation and climatical factors, it seems that study new diseases or strains of cassava disea se tend to appear each 7Ã¢â¬10 years. Table beneath shows the disease problem in Arica.\r\nbiological methods/ processes- biological aver of invasive species.\r\nCassava mosaic and mealybug control programs were introduced in the 1970s (2) to combat these two problems, the slump in lay out because of the mealybug eating the plant and come along decline because of the spread of disease. The Institute of Biological Control (CIBC) base in Trinidad and the International Institute of tropical Agriculture (IITA) looked into how the mealybug was kept under control in South America. They at last found that a tiny white Anglo-Saxon Protestant ( secondaryer than the head of a pin) called the Leptomastix, which laid its bollock on the mealybug was keeping the mealy bugs under control wherefore defend the cassava plant. The picture on the right shows the small wasp on the mealybug larvae.\r\nYou can read also Costco quality Study\r\nThe picture on the left shows an infected cassav a tuber take outside from the field and sliced open. The wasps were able to control the cassava eating the cassava harvest-tides by the wasp laying eggs on the mealybug they grew on the mealybug, the wasp larvae wherefore killing the mealybug this would bring in a commodious effect on the tribe as seen in South America, of the mealybug and thitherfore restoring the natural proportionateness. This could be the unc all overing that they were looking for and could control the mealybug.\r\nMeeting the take exception\r\nTests were run on the wasp by the CABI Bioscience in the UK. on that point the mealybug was tested to see how highly unique(predicate) they are to the cassava mealybug soldiers because if they were not then they could also continue early(a) insects in the continent and thereof would be too dangerous to introduce to the area. The results showed that the wasp was highly specific to the insect (mealybug) so were given the okay to be shipped to Africa so they th en can be reared and then the distributed to other areas around Africa. This was a huge breakthrough as without this look it had the ability to cause huge prostitute on the surround and the saving because of further violate to other line ups.\r\nAppropriateness.-Has been successful with the mealybug.\r\nThe mealybug feeds on the cassava stem, petiole, and foliage well(p) the growing point of the cassava plant. During feeding, the mealybug injects a toxin that causes leaf curling, slowing of lose it growth, and eventual leaf withering. This is the effect the cassava mealybug has on the plant resulting in a huge loss of exploit due to infested plant crop. The yield loss in infested plants is estimated to be up to 60 part of root and 100 percent of the leaves the root is the main source of nutriment so this causes a huge problem for the crop yield. The results were a reduction in mealybug damage was seen in the starting line season following release in both the leaf and the root, and full control was typically achieved within 2Ã¢â¬4 years (6) after and now after a decade (10 years) the cassava mealybug and the wasps lived in natural balance with the mealybug population come out to a utmost of 10% of what they were 10 years past at a peak of the infestation.(1) now the cassava can grow with no or little damage from the mealybug as the wasp has stopped the 60% root damage and the 100% of leaf destruction. Yield losses as report by farmers are averaged at around 80% during the 1983 cassava mealybug volcanic eruption but were reduced to 43% in 1979 pre infestation levels. (7)\r\nImplications\r\nEnvironmental- An environmental implication is that when the wasps are introduced to south America there was a fortune that it could stick a huge impact on the food reach as by taking away oneness organism or gaining one can have a bug on effect on others for example of the wasp was then hunted by a predator this could leave its dominion pray to multipl y therefore having an over population which in turn can then have overhead on effects to their pray and so on and so on until defunctness of a food source. Causing problems for South America in the economy and for the environment also. This environmental implication causes an imbalance of the natural balance of wildlife; this may have a knock on effect of the overall environmental surrounding and the effect on the gracious population.\r\nEconomic\r\nFor the farmers of Africa the economic impact has been helpful and successful by increasing dramatically there yield percentage therefore increasing the money income. E truly jam of investment in the mealybug assure control work has returned between two hundred and d pounds. These improvements to the environment from this environmental source with no costs but a huge increase in crop harvest, obviously is a clear improvement economically to the farmers. By introducing the wasps there lead be a series of tests that impoverish ment to be run before can be realised for example examen the wasps to see if they were highly specific to the mealybug and whether they would cause destruction on other pests in the environment. The cost of setting up the project is costly especially as it is a longitudinal study so forget have a mammoth amount of money spent which will be spent over the years as has to be monitored over the years.\r\nBenefits to the creation\r\nThere was a desperate claim for something that could stop the crop destruction on the cassava plant and by determination the wasp that ate the mealybug which was destroying the crop made the crop loss reducing dramatically There was 80% of crop lost so with the help of the cassava mealybug project has gone down to 43 % (7) this a huge benefit for the locals economically it brings in more income for them and also more food, As is a astronomical food source for the local people. The cassava plant is the third-largest source of food carbohydrates in the tropic area. The cassava is a major food in the developing world, providing a basic diet for around 500 million people. Cassava is one of the most drought-tolerant crops, capable of growing on borderline soils. Nigeria is the worlds largest producer of cassava. The cassava is a corking source of carbohydrate for the people although it lacks in protein.\r\nRisks to the environment\r\nAlthough there is many reasons why there was a need for this biological control of the cassava mealybug, but there was also a huge risk of the environment being destroyed for example, if the wasp was not highly specific to the mealybug and caused a different crop to grow out of control this could also be active the natural balance of the environment resulting in and upset of the natural predators food source threesomeing to disruption of habitat and extinction of some insects which will have a large effect on predators high up the food chain. The wasp being introduced to the environment could have caused further damage on the environment destroying the local farming if it had effected another plant in the environment with could have caused further damage on the local economy and their food source. The food chain on the right shows how a small animalÃ¢â¬â¢s decrease of extinction would affect along the food chain resulting in effecting the highest food predator and can easily lead to extinction of this animal.\r\nAlternative solutions\r\nPesticides can be used to control out breaks of mealybugs. It is not very easy to control, as the cassava mealybug is covered in hydrophobic bestride which repels water-based insecticides therefore making it very difficult ton successfully irradiate the mealybug using this method of biological control. Also unless mealybugs are sprayed with the insecticide at certain times the treatment will not be effective. Firstly because mealybugs are protected from aqueous sprays by their move up coat and seek sheltered sites at certain points in which to feed, insecticides must be applied when mealybugs have least full and are most exposed. This time is in early spring as the mealybugs will feed on the foliage and at this point the mealybugs are young and have not had enough time to produce the full thick layer of wax coating.\r\nAnd therefore this leaves the mealybug unprotected from the insecticide. There are also fewest leaves at this point so is harder for the, mealybug to extend from the insecticide resulting in a high success rate. Insecticides applied after Christmas has limit effect, Once mealybugs have established there position on the plant (usually from mid-January onwards), they are virtually im achievable to remove or control with insecticides at this stage therefore this means that there has to be a lot of research gone into discovering the consummate time to use the pesticide therefore be a lot as is a longitudinal study and may divert from year to year.\r\nGenetic modification.\r\nAnother scuttle tha t is being looked into it hereditary modification of plants, this was through with(p) by Dr Stanford. He was looking into crop improvement and saw the power of genetic selection and how there was limited changed possible using just selective breeding. He then became involved in plant genetic engineering research and showed that there were numerous genes which were potentially useful in crop plants but they were struggling to project a method for delivering these genes into the plant genome, there was no transformation technology(8) . Further research showed that shooting DNA into cells thereby penetrate cell walls and membranes. This was called the gene accelerator pedal and it was able to transform early transgenic crops. This gene gun would be able to in conjecture change the genetic makeup of the cassava plant so that it could offer some sort of protection against predators. This would also have risks as you do not distinguish how the modification will affect all of its pr edators and could therefore have an effect on them so may cause maltreat in some way. Although there is less risk in destroying the natural environment as it is not causing other insects a problem.\r\nConclusion\r\nIn ending the biological control of the mealybug has had a huge effect and has caused the problem of the economy and environment to be resolved therefore keeping harmony between the organisms and the gay population by keeping a natural balance between the small wasp and the mealybug.\r\n'