Use their sharp mouthparts to extract sap from the plant phloem, weakening the plant. They are also vectors who can transfer pathogens from diseased plants to healthy plants.
How to reduce the number of aphids
1. Chemical pesticides
2. Biological pest control - using ladybirds
Nitrate ions
Required to convert sugars into proteins which are required for the plant to grow. If there is not an adequate supply, the growth of the plant will be stunted.
Magnesium ions
Required to synthesise chlorophyll, which absorbs light energy during photosynthesis. If there is not an adequate supply, the leaves cannot photosynthesise properly and they turn yellow (chlorosis).
