GM Crops
GM (genetically modified) crops are plants that are altered on a molecular level in a laboratory. It has been shown that by modifying these plants that scientists have been able to change their natural nutritional, insecticide resistance and flavor properties to produce better crops.
A study conducted in 1999 showed that pollen from GM crops had caused unusually high mortality rates in Monarch butterfly caterpillars that had consumed pollen which had landed on nearby plants from wind pollination. Obviously, if there is an adverse effect on the Monarch butterfly population then the number of aphids will rise resulting in poorer crops.