Periodic Reporting for period 1 - SOIL-4-CONTROL (Linking plant-soil feedbacks to aboveground-belowground interactions for noxious weed control)
Période du rapport: 2019-04-01 au 2021-03-31
The problem
Invasive alien species (IAS) form one of the major threats to biodiversity worldwide and drive climate change. SOIL-4-CONTROL assessed possibilities for the control of terrestrial invasive plant species in Europe by combining aboveground herbivores as biological control agents and soil-mediated effects. Biological control uses natural enemies of the target, such as herbivores, for control. This method is widely used on other continents, and is a promising new method for Europe. It remains unexplored if soil communities can also be applied to suppress specific invasive plant species, and if this can strengthen biocontrol.
Why is it important for society?
The EU Regulation 1143/2014 on IAS emphasizes the urgent need to mitigate the negative impacts of IAS. Authorities and environmental professionals need methods to effectively control already invaded plant populations.
Objective
Assess possibilities for the control of terrestrial invasive plant species in Europe by combining aboveground herbivory and soil-mediated effects.
Conclusions
Common ragwort, Jacobaea vulgaris, is a worldwide toxic weed of grasslands rapidly expanding in Europe. No proof has been delivered for the suppression of common ragwort via manipulation of the soil, but soil communities affect common ragwort performance and these effects should be considered when implementing biocontrol and restoration programs. Nematodes seemed unsuitable for the suppression of ragwort, but a bacterium was identified that suppresses common ragwort after root inoculation. This species will be further studied by LU.
Common ragweed, Ambrosia artemisiifolia, is an allergenic weed. Field data showed that the accidentally introduced herbivore Ophraella communa strongly reduced seed and pollen production of common ragweed, and has the potential to reduce the health-related costs by 1.1 billion euro annually.
Japanese knotweed, Reynoutria japonica, giant knotweed (R. sachalinensis and their hybrid R. x bohemica are a threat to biodiversity and pose large costs to society. The psyllid Aphalara itadori is a specialist herbivore that was candidate for introduction into the Netherlands (NL). A desk study on the risks and benefits of A. itadori was the basis for the petition for release of this population, which was approved by the Dutch government as first exotic weed biocontrol agent in NL. Mesocosm experiments revealed that a recently collected population of A. itadori performs superior on the hybrid.
Invasive alien species (IAS) form one of the major threats to biodiversity worldwide and drive climate change. SOIL-4-CONTROL assessed possibilities for the control of terrestrial invasive plant species in Europe by combining aboveground herbivores as biological control agents and soil-mediated effects. Biological control uses natural enemies of the target, such as herbivores, for control. This method is widely used on other continents, and is a promising new method for Europe. It remains unexplored if soil communities can also be applied to suppress specific invasive plant species, and if this can strengthen biocontrol.
Why is it important for society?
The EU Regulation 1143/2014 on IAS emphasizes the urgent need to mitigate the negative impacts of IAS. Authorities and environmental professionals need methods to effectively control already invaded plant populations.
Objective
Assess possibilities for the control of terrestrial invasive plant species in Europe by combining aboveground herbivory and soil-mediated effects.
Conclusions
Common ragwort, Jacobaea vulgaris, is a worldwide toxic weed of grasslands rapidly expanding in Europe. No proof has been delivered for the suppression of common ragwort via manipulation of the soil, but soil communities affect common ragwort performance and these effects should be considered when implementing biocontrol and restoration programs. Nematodes seemed unsuitable for the suppression of ragwort, but a bacterium was identified that suppresses common ragwort after root inoculation. This species will be further studied by LU.
Common ragweed, Ambrosia artemisiifolia, is an allergenic weed. Field data showed that the accidentally introduced herbivore Ophraella communa strongly reduced seed and pollen production of common ragweed, and has the potential to reduce the health-related costs by 1.1 billion euro annually.
Japanese knotweed, Reynoutria japonica, giant knotweed (R. sachalinensis and their hybrid R. x bohemica are a threat to biodiversity and pose large costs to society. The psyllid Aphalara itadori is a specialist herbivore that was candidate for introduction into the Netherlands (NL). A desk study on the risks and benefits of A. itadori was the basis for the petition for release of this population, which was approved by the Dutch government as first exotic weed biocontrol agent in NL. Mesocosm experiments revealed that a recently collected population of A. itadori performs superior on the hybrid.
Studies on common ragwort
We used the study species common ragwort to assess possibilities for combining aboveground herbivores as biological control agents and using soil-mediated effects to suppress the species. A desk study analysing data from a mesocosm experiment of 13 plant species and nematode communities showed that soil nematode communities change the outcome of plant-plant interactions, often in favor of common ragwort. Therefore, plant-feeding nematodes are no candidates for ragwort control via the soil. A manuscript has been submitted to Plant and Soil and a revision is now in review.
We identified a bacterium with negative effects on common ragwort seedling growth when roots were inoculated. Inoculation with this bacterium and feeding by caterpillars of the specialist herbivore moth Tyria jacobeae had additive but no synergistic effects on plant growth. The group of Prof. Bezemer continues to study whether this bacterium could be used for suppression in the field.
Observations in the field showed that the spatial arrangement of common ragwort seedlings is affected by conspecific plants that grew there earlier, likely through soil-mediated effects (plant-soil-feedbacks). At short distances, seedling recruitment seems to be suppressed by high densities of conspecific adults. A scientific manuscript is being prepared.
Studies on common ragweed
Two field data sets from common ragweed previously collected were used to analyse the impact of an exotic biocontrol agent in the field. Data constituted the abundance and damage of the leaf beetle Ophraella communa on hundreds of individual common ragweed plants. The results proved that O. communa can strongly reduce seed and pollen production of ragweed and that in-season leaf damage by O. communa helped to explain this impact.
The other data set showed that O. communa reduced ragweed pollen production in the field by ca. 80%. By integrating these data into spatial models, we showed for the first time for Europe that costs of invasive ragweed ( 7.4 billion euro annually) can significantly be reduced (by 1.1 billion euro/ year) by this biocontrol agent.
Scientific papers have been published open access in Neobiota and in Nature Communications.
Studies on invasive Asian knotweeds
A desk study confirmed the host specificity of A. itadori, and the minimal risks for the Dutch flora potentially resulting from a release into the wild. This was used to submit a petition for release to the Dutch government in December 2019, which was approved in July 2020. Mesocosm experiments showed the psyllid performs superior on the hybrid. A manuscript is in preparation for Neobiota. The results have improved the rearing and release program of A. itadori in the NL and have attracted a lot of international media attention.
Training and knowledge transfer
I actively participated in activities of LU, co-supervised (under)graduates, did 2 secondments at the research institute CABI. I was in the Steering Committee of the public-private consortium #uitde1000knoop, realising the implementation of the first exotic weed biocontrol agent in NL, and wrote a follow-up proposal (‘BioCops’) submitted to LIFE+.
I transferred knowledge by teaching/ supervising LU students , and to stakeholders by numerous activities and outreach activities.
Dissemination
Over 10 stakeholder activities such as workshops and webinars in NL and Belgium, 6 articles in professional journals. To the general public a website, tens of posts on social media (Twitter, LinkedIn) and >20 media items (national TV/radio in NL, Belgium and UK), and a class for schoolchildren.
We used the study species common ragwort to assess possibilities for combining aboveground herbivores as biological control agents and using soil-mediated effects to suppress the species. A desk study analysing data from a mesocosm experiment of 13 plant species and nematode communities showed that soil nematode communities change the outcome of plant-plant interactions, often in favor of common ragwort. Therefore, plant-feeding nematodes are no candidates for ragwort control via the soil. A manuscript has been submitted to Plant and Soil and a revision is now in review.
We identified a bacterium with negative effects on common ragwort seedling growth when roots were inoculated. Inoculation with this bacterium and feeding by caterpillars of the specialist herbivore moth Tyria jacobeae had additive but no synergistic effects on plant growth. The group of Prof. Bezemer continues to study whether this bacterium could be used for suppression in the field.
Observations in the field showed that the spatial arrangement of common ragwort seedlings is affected by conspecific plants that grew there earlier, likely through soil-mediated effects (plant-soil-feedbacks). At short distances, seedling recruitment seems to be suppressed by high densities of conspecific adults. A scientific manuscript is being prepared.
Studies on common ragweed
Two field data sets from common ragweed previously collected were used to analyse the impact of an exotic biocontrol agent in the field. Data constituted the abundance and damage of the leaf beetle Ophraella communa on hundreds of individual common ragweed plants. The results proved that O. communa can strongly reduce seed and pollen production of ragweed and that in-season leaf damage by O. communa helped to explain this impact.
The other data set showed that O. communa reduced ragweed pollen production in the field by ca. 80%. By integrating these data into spatial models, we showed for the first time for Europe that costs of invasive ragweed ( 7.4 billion euro annually) can significantly be reduced (by 1.1 billion euro/ year) by this biocontrol agent.
Scientific papers have been published open access in Neobiota and in Nature Communications.
Studies on invasive Asian knotweeds
A desk study confirmed the host specificity of A. itadori, and the minimal risks for the Dutch flora potentially resulting from a release into the wild. This was used to submit a petition for release to the Dutch government in December 2019, which was approved in July 2020. Mesocosm experiments showed the psyllid performs superior on the hybrid. A manuscript is in preparation for Neobiota. The results have improved the rearing and release program of A. itadori in the NL and have attracted a lot of international media attention.
Training and knowledge transfer
I actively participated in activities of LU, co-supervised (under)graduates, did 2 secondments at the research institute CABI. I was in the Steering Committee of the public-private consortium #uitde1000knoop, realising the implementation of the first exotic weed biocontrol agent in NL, and wrote a follow-up proposal (‘BioCops’) submitted to LIFE+.
I transferred knowledge by teaching/ supervising LU students , and to stakeholders by numerous activities and outreach activities.
Dissemination
Over 10 stakeholder activities such as workshops and webinars in NL and Belgium, 6 articles in professional journals. To the general public a website, tens of posts on social media (Twitter, LinkedIn) and >20 media items (national TV/radio in NL, Belgium and UK), and a class for schoolchildren.
Scientific impact
Studies on common ragwort have given new insights into soil-mediated effects on ragwort. Contribution to the first and high-impact publication on potential monetary benefits of weed biocontrol in Europe.
Socio-economic impact
The potential monetary benefits of biocontrol demonstrated can increase appreciation of biocontrol as a novel method to manage invasive plants in Europe.
The project contributed to the approval and release of the knotweed psyllid for the control of invasive Asian knotweeds in NL. This was the first time that the Dutch government approved the release of an imported exotic weed biocontrol agent. The project has improved the rearing and release program.
The numerous dissemination activities and tremendous media coverage have likely raised awareness on invasive plant species, and the potential of biological control as a cost-effective and safe solution, and increased the visibility of LU in this field.
Career impact
The fellowship has strengthened my skills to become a principle investigator. I have started my new job as a team lead at the R&D department of the multinational company Koppert Biological Systems, world-leading in natural pest control, while staying connected to LU as a guest researcher.
Studies on common ragwort have given new insights into soil-mediated effects on ragwort. Contribution to the first and high-impact publication on potential monetary benefits of weed biocontrol in Europe.
Socio-economic impact
The potential monetary benefits of biocontrol demonstrated can increase appreciation of biocontrol as a novel method to manage invasive plants in Europe.
The project contributed to the approval and release of the knotweed psyllid for the control of invasive Asian knotweeds in NL. This was the first time that the Dutch government approved the release of an imported exotic weed biocontrol agent. The project has improved the rearing and release program.
The numerous dissemination activities and tremendous media coverage have likely raised awareness on invasive plant species, and the potential of biological control as a cost-effective and safe solution, and increased the visibility of LU in this field.
Career impact
The fellowship has strengthened my skills to become a principle investigator. I have started my new job as a team lead at the R&D department of the multinational company Koppert Biological Systems, world-leading in natural pest control, while staying connected to LU as a guest researcher.