One of the most common pesticides in the agronomy industry is DDT (Dichloro-Diphenyl-Trichloroethane), it was discovered in 1939 by a Swiss chemist, Paul Müller. DDT is commonly used because it is; toxic to a broad spectrum of insects, yet displayed low toxicity to mammals (meaning that small animals and humans were not affected), it was persistent and did not need to be reapplied often and it was water insoluble, and was impervious to rains. Those reasons, combined with the fact that it was inexpensive and widely available, made sure that it would be massively popular before being banned in the 1980s after being found to destroy bird populations as birds which came into the contact of DDT, developed thinned eggshells on their eggs. DDT functions to kill pests by interfering with nerve impulses of the organism, which paralyses it and therefore kills it. A foresight we did not take however, was that some insects had genetic mutations which made them invincible to these sorts of chemicals and thus they survived and went on to reproduce allowing their offspring to inherit these mutations to their genes and therefore be able to survive insecticides. In the nucleus of the cell, resides the chromosome strands (genes) and the genes consist of Deoxyribonucleic acid, or DNA (Refer to diagram 1). Each gene has a specific instruction, specified by the DNA, for …show more content…
The technique does not encompass any pesticide at all. It is employed to deter pests from consuming the crop, by placing another plant which the insect prefers next to it, so as to draw the insect to that plant and save the crop. For example, the crop is watermelon and you place marigold next to it, so the marigold draws the insects, leaving the watermelon safe. Another utilisation for companion planting could also be when an animal does not like a specific vegetable and will not go near it, if that plant is placed close to the crop, the insect will not go near the crop, for example; you could place watermelon next to Poisonous Hemlock and the insects would be deterred by the Hemlock and not eat the watermelon. To do this, many gardens place complementing plants in alternate patterns (refer to diagram 3), so as to double the benefits in a sense and protect against two insects – in example; Bug A likes carrots but despises beets and Bug B likes beets but despises carrots so neither will go near the vegetables. Companion planting uses absolutely no pesticides and is the most cautious of the eco system as it does not specifically harm the insect population however it is not nearly as effective as the other methods, as plants decompose quickly it also does not leave much if any contaminants behind. Companion planting also requires more time – in order to plant the seeds