Wetter Climes Increase Aphid Crop Damage

Milder UK winters are resulting in increased crop damage from aphids, research from the Rothamsted Institute has found.

Aphids are now appearing up to four weeks earlier than the long-term average; the findings indicate that for every 1 degree centigrade rise in January or February the aphids are emerging 8 days earlier than on average in the 42 years the research has been going on at Rothamsted. Of particular concern is the peach-potato aphid (Myzus persicae), which feeds on a variety of plants including fruits and vegetables, having been recorded as emerging two weeks earlier than the long-term average.

Dr Richard Harrington of the Rothamsted Insect Survey described how warmer winters lead to earlier emergence or advanced phenology:

"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... are appearing significantly earlier in the year and in significantly higher numbers... ...after a warm winter, there are much larger numbers flying and they are hence detected much earlier. This means that there are more aphids flying in spring and early summer, when crops are particularly vulnerable to damage."

Aphids are important vectors of a variety of diseases that affect fruit and vegetables including strawberries and tomatoes. They also inflict damage on crop plants directly by predation. Crops such as potatoes are particularly vulnerable to aphids whilst they are young - exactly the time when aphids are increasingly beginning to emerge in their greatest numbers.

Dr. Harrington envisages that if current trends continue, aphid numbers could increase 10-fold over the next fifty years.

Now that the BBSRC funded research has identified this problem, mitigation options can be considered for the future to prevent serious crop loss.

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