Epidemics are often reported on the news; swine flu, spanish flu, bird flu… the list goes on. However, in general, people are infrequently aware of the threat of pests and the impacts they can have on agriculture.
A pest is described in the Oxford dictionary of biology as ‘any organism that harms crop or livestock or otherwise interfere with the well-being of humans’ and we are facing a pest invasion right now.
Diamond-back moths have been reported in the media as a ‘biblical’ problem in Britain recently. These insects originated from the Mediterranean but spread worldwide and are now found in Europe. The moths have been brought to Britain recently, in particular, due to strong winds from continental Europe which has caused a huge increase in their number to levels as high as in 1996, reported by Dr Steve Foster and his team at Rothamsted Research, in Hertfordshire.
But why are these moths thought to be such a problem? Well, some evidence suggests that they are able to decimate crops such as cauliflower, broccoli and cabbage in a matter of hours so yield of these is expected to be lower this year. This, in turn, would cause prices of these vegetables to increase as farmers have fewer to sell, so… no one is happy. What’s more, is that the Diamond-back moth is thought to be resistant to insecticides and scientists are frantically testing many compounds on the larvae. To add to the problem further, female moths have been reported, in some rare extreme cases, to lay up to 200 eggs on a leaf.
However, upon speaking to Dr Steve Foster himself, it does seem that the ‘biblical influx’ reported in the media, is not as worrying as it first seems. The population changes of this species of moth are seasonal and it is incredibly rare to see such high numbers. Moreover, evidence in the field suggests that in some places where there are relevant crops, the moths don’t actually lay eggs.
It seems these pests really aren’t as much of a problem as it would first seem for farmers with any impacts being short term, affecting this year’s yield only. Futhermore, even Dr Foster himself said that is not for definite that these pests decimate crops. The main task is to find an effective insecticide and find the correct ‘susceptible baseline dosage’, so that the crops and any mutualistic (beneficial) insects are not killed. So, for now, these moths are a problem, but it will only be a matter of time before they are forgotten about.