The Heat Is Online

Warmer Winters Boost Plant-Destroying Aphids

Global warming boosts garden pest

Milder winters caused by climate change are providing a boost to plant-damaging aphids, scientists have warned.

Researchers revealed the familiar garden pest was flying earlier and in larger numbers because of warm conditions in winter and spring.

As a result more aphids are on the wing and looking for food in spring and early summer when crops are at their most vulnerable.

The scientists at Rothamsted Research in Hertfordshire said aphids were an important indicator of warming temperatures in the UK. One of the UK's most damaging aphids, the peach-potato aphid, is flying two weeks earlier for every 1C rise in average temperatures in January and February, researchers said.

This year the first aphid was caught on April 25 - almost four weeks ahead of the 42-year average, research in the Biotechnology and Biological Sciences Research Council's BBSRC Business magazine revealed.

The common greenfly pest feeds on a wide variety of plants, including flowers, fruit and vegetables. It damages the plant by sucking its sap or by injecting a virus which can lead to the plant's death. Aphids also secrete a sticky honeydew as it feeds, which can cause sooty moulds on the plant which prevent sunlight reaching the leaves.

Dr Richard Harrington, of the Rothamsted Insect Survey, said: "One of the most noticeable consequences of climate change in the UK is the frequency of mild winters. As a direct result of this, aphids seeking new sources of food are appearing significantly earlier in the year and in significantly higher numbers.

"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.

"After a warm winter there are much larger numbers flying and they are hence detected much earlier. This means there are more aphids flying in spring and early summer, when crops are particularly vulnerable to damage."

Scientists at Rothamsted, backed by BBSRC, have been monitoring flying aphids for 42 years, using a network of suction traps in England and Scotland to collect a representative sample of flying insects.