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1. Pesticides can be sprayed onto date palms to kill pests. This can damage the environment.
(a) Outline the damage to the environment that may be done by spraying pesticides.
An alternative to using pesticides is biological control. The Senegalese grasshopper is a serious pest
in West Africa. A fungal parasite of grasshoppers is used as a means of biological control. Spores of
the fungus are sprayed onto populations of grasshoppers.
An investigation was carried out to compare this biological control with a pesticide.
Three fields were treated as follows:
· sprayed with fungal spores
· sprayed with pesticide
· not sprayed
(b) Explain why one field was not sprayed
(a) Effects of pesticides on the environment:
Pesticides that are sprayed on to fields and used to fumigate soil can give off chemicals called
volatile organic compounds, which can react with other chemicals in the air and form a pollutant
called tropospheric ozone, which in high concentrations can lead to smog.
Pesticide particles can drift when released into the atmosphere, especially in areas with low
humidity and high temperatures, posing a threat to wildlife if there is a high amount of inhalable
pesticides in the air.
They can leach through the soil and runoff into waterbodies and drinking water, killing aquatic
life by eutrophication, due to higher nutrient levels, which kills submerged plants by blocking
light penetration so they cannot photosynthesize and therefore die causing a rise in the microbe
population, and depleting oxygen levels through decomposition of dead matter. Therefore
aerobic plants and animals will die causing a further increase in the microbe population. This will
make the water anaerobic and cause the release of methane from the water, which is a
greenhouse gas, and constitutes to global warming. Humans who drink the contaminated
drinking water fall ill or die as pesticides bioaccumulate in body fat. Pesticides may also be
carried to water by eroding soil.
Pesticides can kill bees when they ingest nectar from plants which contain pesticides, which
cause a decrease in pollination of insect pollinated plants and the loss of species that pollinate
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One field was not sprayed to see the condition of crops without fungal spores and pesticides, so
that it could be used to compare with the other two fields individually to see the change in the
condition of each of their crops and therefore deduce the better field.…read more