Biocontrol
Biological control – or biocontrol – has been used effectively against invasive species for over 100 years.
It is the use of living organisms, such as insects or pathogens, to control pest populations. It levels the playing-field by reintroducing some of the specialist natural enemies that help control the invasive species it in its native range. The aim of biocontrol is not to eradicate the invasive species, but control it in a way that it becomes manageable (CABI, 2021).
Our current use of biocontrol has a specific focus on Himalayan balsam and Japanese knotweed.
HIMALAYAN bALSAM
Impatiens glandulifera
ID
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Can Grow 6-10 ft tall
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Slightly serrated green oval shaped leaves, edged in red.
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The stem is hollow, red-jointed, and hairless.
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White to deep pink trumpet shaped flowers
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Sweet Smelling
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Explosive Seed Pods
PROBLEMS
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Creates monocultures taking over large areas of land reducing biodiversity and restricting native plants from growing.
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Causes decline in invertebrate species (spiders, ground beetles and true bugs) affecting the food chain.
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Dies back over the winter leaving ground bare and susceptible to erosion making riverbanks unstable.
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Erosion causes an increase in pollution and sediment into waterways causing declines in fish and other species.
BIOCONTROL
We work with the Centre for Agriculture and Biosciences International (CABI). This is how we get our biocontrol.
For Himalayan balsam, this is a rust fungus which infects the undersides of the plant leaves.
This rust fungus has a very complicated 5 stage life cycle which follows a similar pattern to that of Himalayan balsam. This means when the plant dies back in the winter, the rust stays within the leaf litter, infecting upcoming shoots in the Spring. This form of biocontrol aims to be a long term self sustaining way of controlling Himalayan balsam, giving native species a chance to grow and improve biodiversity on the river.
We currently have several sites spread throughout the catchment from Hartlepool all the way across to Barnard Castle, with the intention of getting more sites to control this invasive species.
Japanese Knotweed
Reynoutria japonica
ID
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Can Grow up to 10 ft tall
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Shield shaped leaves in zig-zag pattern
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Small white flowers
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They have clearly visible nodes between stem sections, which makes them look like bamboo.
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Form dense clumps
PROBLEMS
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Can cause devastating costly damage to its surrounding environment.
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It has a vigorous rapidly growing root system that frequently damages property foundations, flood defences, and pavements.
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Grows in large quantities outcompeting native species for space and light.
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Costs the UK thousands of pounds per year to control.
BIOCONTROL
We work with the Centre for Agriculture and Biosciences International (CABI). This is how we get our biocontrol.
For Japanese knotweed, this is a psyllid that spends its life cycle on and around the plant.
The psyllids are small sap sucking insects which slow the growth of Japanese knotweed. They lay eggs on the leaves and live on the plant as many generations. This form of biocontrol aims to be a long term self sustaining way of controlling Japanese knotweed, giving native species a chance to grow and improve biodiversity on the river.
We currently have several sites spread throughout the catchment based predominately around Darlington, with the intention of getting more sites to control this invasive species.
external BIOCONTROL RESOURCES
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FUNDING
The biological control work was initially funded by the Green Recovery Challenge Fund as part of the Heritage Lottery Fund. We received £179,000 from the lottery in order to create 11 rust fungus biological control sites for Himalayan balsam, and 5 psyllid biological control sites for Japanese knotweed. This project was for 1 year (2021-2022) and aims to be a long term solution for control of invasive non-native species. So far we have seen great success in the establishment of these agents.
Due to the success of this project we have received a further £5,000 from Northumbrian Water, to create another Himalayan balsam biological control site, which will be released in the summer of 2022.
We hope to gain more funding in the future to carry out this work, as we believe it is an amazing management technique for managing INNS.
