Knotweed to be unravelled at last?

An insect has been identified that just might prove to be the holy grail of biological control: a safe predator for Japanese Knotweed.

Japanese Knotweed (Credit: ultra megatron)

The Commonwealth Agricultural Bureaux International has announced plans to begin consultation on the use of a Japanese psyllid to attack knotweed in the UK. If approved, this will be the first time an exotic species has been used in Britain to control a plant. Psyllids or jumping plant lice are true bugs, and look rather like aphids. They are small plant-feeding insects that tend to be very host specific, feeding on one (or a very few) plant species. For this reason they could be ideal for biological control. The problem, of course, is that biological control has a terrible reputation for doing more harm than good. Cane toads are perhaps the best known example of this going wrong. The Telegraph has helpfully compiled a list of successes and failures in biological control. Perhaps psyllids will soon be on the list – but in which column?

2 thoughts on “Knotweed to be unravelled at last?”

  1. Will this bug also attack members with the Japanese knotweed family of which no doubt there will be several native UK plants.Were all the other 100 or so plants tested not members of the same family as J.knotweed hence the bug did not affect them?

    The Ranger responds: that’s the key thing that the researchers will need to establish. There are not actually any close relatives of Japanese Knotweed which are native to the UK, but they’ll no doubt be checking the effect of the psyllid on other species as a part of the research programme. CABI said:

    The safety [of the biological control agents] will be assessed using field observations and host specificity testing in our Defra-licenced quarantine facility. All work will be carried out according to international protocols and there is no commitment to release.

  2. Won’t the psyllids just be eaten by the introduced harlequin ladybirds?

    The Ranger responds: that would be irony indeed!

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