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Global Ecological Problems and Issues of Ecological Democracy in the Beginning of the New Millennium

A Discussion Paper for the Vasudhaiva Kutumbakam Ecological Democracy Working Group

 

 

 

 

 

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Loss of Biodiversity and Genetic Erosion                                                                                                                     ...Contd.

Modern monocultures are in direct contrast with this philosophy. They often grow only one genetically uniform variety of a single species at a time. This kind of fields can, at their worst, become real super-highways through which various plant diseases and pests can spread with astonishing speed, destroying whole crops while they proceed.

One of the most dramatic examples of what can happen was the Irish Potato Famine in the 1840s. Practically all the potatoes grown in Ireland at that time belonged to a few cultivars, none of which was resistant to a fungus called potato blight. When potato blight hit Ireland the whole crop was destroyed. One million people died in the famine and two million more had to emigrate to America. The population of the island was cut from six million to about three million in only a few years.

What if something similar would happen to the most widely spread rice cultivars that have replaced tens or hundreds of thousands of local varieties during the last decades? As Richard Douthwaite has observed: "...very few people also know that the (food) system is genetically unsustainable and might suddenly collapse, causing the deaths of hundreds of millions of people from starvation and leading to political, social and military consequences comparable to those of a nuclear war."

In a monoculture damages caused by pests and plant diseases are fought by two different methods. First, whenever a new disease or pest becomes a truly major problem, plant breeders try to breed new varieties that are resistant to the disease or pest in question. However, this takes so much time that often a lot of damage is done before the new, resistant varieties are available. Also, the resistant plant varieties are usually not resistant for a very long time. Plant diseases and pests evolve and mutate all the time, and because their breeding populations are very large and genetically diversified, it won't usually take long before they have overcome the problem. In other words: the resistance bred to cultivated plants is not permanent but has to be replenished and renewed over and over again with new genes.

As Dr J.P. Kendrick from the University of California puts it:

"If we had only to rely on the genetic resources now available in the United States for the genes and gene recombinants needed to minimize genetic vulnerability of all crops into the future, we would soon experience losses equal to or greater than those caused by southern corn leaf blight several years ago - at a rapidly accelerating rate across the entire crop spectrum."

The problem is, that when the genetic basis of the cultivated plants becomes more narrow, the plant breeders will have less material that they can use in order to renew the resistance of the plants against diseases and against the at least 15 000 known species of pests.

There has been a serious effort to save the various cultivars of important food plants by storing their seeds into international gene banks. However, seed can only be stored in a gene bank for a certain time before they lose their ability to germinate. This means that the stock have to be regenerated within a certain period of time by sowing the seed out and storing the new seed. However, the new seed will not be genetically identical with the original variety that had been stored into the gene bank. The original variety is a result of evolutionary adaptation into the conditions in a certain locality. When seeds collected from thousands or tens of thousands of different localities will be sown on the same locality, the process favours the varieties and traits that match the requirements and conditions of that particular site. Other kinds of characteristics - unfavourable for that particular site - and genetic material responsible for them will irrevocably be lost. Thus the gene bank approach will not be able to preserve genetic diversity for centuries. The only way to do this is to pay for individual farmers or village communities for maintaining small local seed collections on hundreds of thousands of dirrecent sites.

The other way to limit the damage is the use of pesticides and fungicides. This has proved to be a very problematic approach. Pesticides also kill the natural enemies of the pests, and sometimes the populations of the targeted pests recover much quicklier than those of their main predators. In field trials wrongly timed and measured applications of pesticides have sometimes increased pest populations by 1250 times.

Extensive use of insecticides has led to the resurgence of several insect pests of rice that were of only minor importance, before. One of them is the brown planthopper, which became Asia's most damaging rice pest in the 1980's, and started to consume rice crops in South and South-East Asia with an unprecedented rate.

In the USA it has been estimated, that crop losses due to pests would increase from 33 to 42 per cent, if the use of pesticides would be eliminated. It is interesting to note that the Americans currently lose - in spite of extremely heavy use of pesticides and other agricultural chemicals - one third of their crops to pests. It would be interesting to compare these figures to the losses suffered in the traditional farming systems that do not use any pesticides or fungicides, but which cultivate dozens of different plants and trees in the same land area. It may be that they have suffered much smaller losses.

Still another problem is the development of resistance to chemicals. The ability of the pests, viruses and fungi to adapt to changing environmental conditions also includes an ability to develop resistance to human-made poisons. When some individuals in a pest population find a way to survive a pesticide, all further spraying favours the individuals with the genetic or behavioural characteristics which allow them to survive the chemical. Because the pesticide will kill most other insects, the resistant pest population soon starts to dominate the area.

Chemical industry has tried to develop new pesticides in order to replace the older ones which have become almost useless in many areas. This far the pests have been able to develop new resistant strains much more quickly than the scientists have been able to create new poisons. According to Dr Sawicki of the Rothamstead Experimental Station: "Estabished resistance can be dealt with only by switching to alternative pesticides to which there is no resistance. This, however, is a transient solution because with time resistance develops to the alternative, which must be replaced by yet another compound. Each new insecticide selects in turn one or more mechanisms of resistance, and each mechanism usually confers resistance to several insecticides."

The development of resistance has often forced farmers to use very heavy doses of several different pesticides. According to the latest estimate, up to 300 000 people may annually die of pesticide poisoning. Pesticides kill bees and other insects that have a great value as pollinators of fruit trees and of many other important crops. If there are too few pollinators, the crops of insect-pollinated crops are reduced.

In many countries fish and shrimp harvested from rice paddies have been an important source of animal protein for the people. In Indonesia, for example, fish farming in rice fields used to produce about a quarter of all fresh, closed-water output of fish. In 1969 about 600 000 tons of fish were harvested from three million hectares of rice fields. However, the use of chlorinated hydrocarbons and other pesticides practically eliminated fish and shrimp from large rice field areas - or made them too poisonous for human consumption. This was one of the reasons why Indonesian government became so interested in the development of integrated pest management (IPM) in the 1980's.

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