A number of off-site laboratories monitoring the flying form of all aphid species have been operating for over four decades. The Rothamsted Research scientists use 16 suction traps — 12 in England and 4 in Scotland — to collect a representative sample of flying insects.
Research showed that the Myzus persicae emerges two weeks earlier for every 1oC rise in mean temperature during the first two months of the year. The Rothamsted Research team found that the first aphid was caught in late April instead of late May.
'One of the most noticeable consequences of climate change in the UK is the frequency of mild winters,' explained Dr Richard Harrington of the Rothamsted Insect Survey. 'As a direct result of this, aphids seeking new sources of food are appearing significantly earlier in the year and in significantly higher numbers,' he added. 'We have been studying the seasonal biology of aphids for a long time now and we know that populations can continue to grow over the winter and spring provided that conditions are warm enough.'
The Rothamsted researcher noted that because a larger number of aphids take flight after a warm winter, they are detected much earlier. 'This means that there are more aphids flying in spring and early summer, when crops are particularly vulnerable to damage,' Dr Harrington said.
The data collected to date can help researchers raise awareness on how aphids and their connection to climate change affect the environment. The information can also give key players the extra boost they need to better determine the timing of aphid control measures.
Besides being key indicators of a changing climate, aphids have the capacity to cause sufficient damage to crops, the researchers said. The findings show that aphids spread plant viruses, weaken plants and extract sap. Because sap is high in sugar, the aphids excrete sticky honeydew, which fuels mould growth. This growth acts as a barrier between the sun and plant leaves; without the sun's rays reaching the leaves, the plants become weak.
The research was funded by the BBSRC. For his part, BBSRC Science and Technology Director Professor Nigel Brown said: 'Environmental change is one of the big challenges facing the world today. These long-term data on seasonal appearance of flying aphids not only show that there are already noticeable changes in UK climate, but they also provide the knowledge which will help to mitigate the consequences.'