Is biological pest control better than chemical pest control?

Rukjit Randhawa

Food is vital for humans to survive, the population of the world is immense as it approaches 6 billion and all these humans need to be fed on a continual basis. Therefore, a large quantity of food needs to be produced rapidly and on a very large scale. Generally farmers across the western world do produce food very quickly and efficiently and there tends to be a surplus of food, whereas, in less developed countries they have a shortage of food. Due to the size of the world’s population and it’s high levels of demand for food farmers are unable to leave crops alone and let them grow naturally. For example, one-third of the crops that are grown worldwide are spoiled by pests, animals particularly insects and many plants.

Certain types of crops grow better in certain set conditions and there are many different factors which effect the crop yield. Crops grow by photosynthesis, the environmental factors affecting the rate of photosynthesis, are light intensity, concentration of carbon dioxide in the air, and the surrounding temperatures. All the requirements for photosynthesis need to be available at a good rate and supply, the light intensity which is usually supplied by the sun needs to be at suitable intensity, which means the crop will only grow certain times of the year due to the amount of light available. The same applies to the concentration of carbon dioxide, which usually does not tend to cause a problem, as there is ample supply of carbon dioxide in the surrounding air, however if it is ever to run low the crops will not grow. The temperature is another factor which has a huge effect on the growth of crops, if the temperature is to get too high this would prevent any growth of the plant as it would not be able to deal with the extreme temperature killing off the chlorophyll that the plant requires to grow. However if the temperature is decreased to a very low temperature this will restrict any growth, as the plant will not be able to function properly. Therefore, all these factors need to be at the correct rate for the crop to be able to grow sufficiently.

Many different types of crops such as maize, corn, wheat, rice, fruit and vegetables are grown at different times throughout the year and most farming is usually based on monoculture. Which is where one type of crop is grown in a certain piece of land, this technique of mass production tends to cause many problems and is not as straight forward as it seems. If crops are growing extremely well and conditions are correct and all the crops have all their requirements at the right rate and intensity there is still one other factor which would still prevent a perfect yield from being produced which are known as pests. These pests still destroy all crop yields, by destroying the crop its self and restricting growth in certain ways. When crops are grown they are just like plants in that they compete for mineral ions, water from the soil and light, however when crops are grown using the monoculture method there usually isn’t a problem because it’s the same crop being grown and so the conditions can be controlled. However, the problems that do arise is that if there is a large concentration of the same crop in one area and they are all in close proximity to each other then there is the potential of the crop being infected by diseases, fungi, unwanted plants and insects which will then lead to the rapid destruction of large areas of the crop.

There are a number of different pests, for example, insects, fungi and weeds that effect individual crops in different ways; like insects, fungi and weeds. Weeds are plants that grow in places we do not want them to grow and there optimum growth occurs in ground disturbed by human activity. They compete with cultivated plants for space, water and minerals. Worldwide, about 10% of crop yield are lost because of weed growth. Weeds tend to come in different sizes and they can be long and the same length as the crops, which means their roots are able to reach deep into the ground and take the nutrients, they require leaving many shortages for the crops. Also weeds can sometimes have broad leafs that cover the crops and so take all the sunlight and restrict the amount of sunlight reaching the crop. The competition between the crops and weed, which is organisms of different species, is known as interspecific competition. Occasionally you may come across weeds that are very small and do not do any real harm to the crops.

The insect pests work in many different ways, each kind of plant has its own species of aphids, and these little creatures have small mouthparts, which they use to suck sap from plants. The loss of sap can be harmful to the plant in many ways in that, it can cause leaves to curl up and become distorted. The leaves are the place where photosynthesis takes place; the curled up leaf leaves the plant unable to photosynthesise efficiently and so can leave the plant stunted. Another way in which aphids can effect crops are, that as the aphids suck in the sap if that crop was diseased they could pick up the disease or virus and then go suck on another plant which would then pass the disease or virus on, which would spread the disease to many plants, any organism which spreads disease or viruses from host to host is known as a vector. Also if the aphids take in to much sap they tend to secrete it through their abdomens, this is usually a sticky honey dew which forms a sticky droplet which attracts ants, which then attack the crop even further. So altogether there are a number of ways in which crops are prevented from being grown.

The ways in which these pests can be controlled and crops can be grown without too many problems is that we can put into the environment a chemical substance that kills the pest, which is called pesticides, or we can put into the environment another organism, which kills the pest, which is known as biological control.

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