Pesticides D. Crowley, 2008

Pesticides To know how pesticides can affect food chains Saturday, April 22, 2017 Pesticides To know how pesticides can affect food chains

Pesticides Read the pesticides assessment sheet, and answer the questions as fully as possible

Pesticides Read the pesticides assessment sheet, and answer the questions as fully as possible

Levels Level 4 – pests are identified, and how these will be affected by pesticides Level 5 – understanding of how changing one aspect of the web can lead to changes in the numbers of the organisms linked to that organism Level 6 – understanding of how one change in a food web can have wide ranging affects, and how this can be both positive and negative for farmers Level 7 – understanding that one change in a food web can have a wide ranging affect, and how this can be both positive and negative for farmers. Understanding of how pesticide can affect organisms further up the food chain, with suggestions for other methods of pest control

Answers Section Producers – dog rose; rye grass; hazel; nettles Insecticides kill insects (pests) which may eat the crops, reducing the amount of money which can be made Caterpillars; ladybirds; aphids; bees; ants; butterflies etc… The wren number will decrease as they will have less food If the wren numbers decreased the number of kestrels would also decrease (less wrens to eat). However the lacewing numbers would increase (less predation) which would directly decrease the number of aphids (as these will be predated more by the increased lacewing population) etc…

Answers Section The number of nettles will increase, as there are less insects eating them a) it preserves organisms in the hedge which might otherwise die; and b) less money is made since the crops growing in the unsprayed area would be attacked by the insect pests Some pesticides can kill useful animals as well as the pests that they were meant to kill. Some pesticides such as DDT can also remain in the environment – bioaccumulation of toxins through the food chain can severely harm or kill higher up organisms, as they are subjected to much higher levels of the toxins Natural pest control (biological control) can be used, introducing natural predators of the pest – this is not quite as effective, but no potentially harmful toxins are introduced