Effects of environmental change: increased nematode pest status on UK crops.

Lead Research Organisation: University of Leeds
Department Name: Ctr for Plant Sciences

Abstract

Plant parasitic nematodes are important, economic, agricultural pests. They cause crop damage both directly as a result of their feeding and as viral vectors of diseases such as spraing on potatoes. Plant parasitic nematodes can be classified as either sedentary e.g. potato and beet cyst nematodes and root knot nematodes, or free-living e.g. stubby root and needle nematodes. Nematicides have historically been used to control nematode problems but have tended to be broad spectrum and relatively persistent. Legislation has already resulted in the recent loss of two major nematicides in response to the environmental concerns that their use raised. Amendments to relevant EU directives will cause loss from the market of the three remaining nematicides with limited prospects for safe alternatives becoming available. The loss of nematicide control and potential changes in climate present a dire situation for many British growers.
Climate change is predicted to increase summer temperatures in the UK by 2.4-4 oC and alter rainfall patterns with summers predicted to be drier by 30% (a median value from several climate models). Climate change could result in increased economic damage caused by nematodes that are already prevalent in the UK. Higher soil temperatures will increase the rate of development of plant parasitic nematodes resulting in greater multiplication of some and hence more damage to host crops. Earlier maturity of potato cyst nematodes may influence the proportion of the second generation that enters a period of dormancy, allowing greater re-infection of the crop within a growing season. The number of generations of beet cyst nematodes may also increase. The impact of cyst nematodes is enhanced when crops must also withstand the abiotic stress of dry soils as reported for potato, beet and other crops.
Climate change may cause nematode species that are prevalent, but infrequently damaging in the UK, to become important agronomic pests. Dry soils are detrimental to control of cereal cyst nematodes. They are normally under natural control from fungi but this suppression is reduced in dry summers because some of their fungal enemies infect nematodes with zoospores that require high soil moisture levels for their activity. This risks damage to the next cereal crop from an increase in overwintering population levels of cereal cyst nematodes. Changes in rainfall will also impact on those free-living nematodes that attack plants. For instance, high soil moisture enhances the activity of trichodorids and longidorids close to the soil surface leading to seedling damage as in Docking disorder of sugar beet.
Increased temperatures could lead to a greater threat from nematode species that are recorded rarely (but when found are present in high numbers) becoming widespread in the UK. There is a risk that alien species of root-knot nematodes, that are abundant elsewhere in Europe, can become established pests as UK soils warm.
In this work, nematologists will collect the biological information necessary for a climate impacts modeller to integrate the new information with that already available to predict increased risks from nematode pests of UK agriculture as climate change continues. Simulation models of UK nematode populations will be developed and tested using primary data relating soil temperature and moisture to nematode development, multiplication rates and crop damage. The model will be refined and tested using secondary biological data prior to being used with the UKCP09 climate data to project the risk of future nematode occurrence. Resolution will be to 25km2 and be related to soil type. The insights gained will be used to develop pest management strategies to mitigate the impact of changes in nematode pest status. This is necessary given chemical control of nematodes as used widely in the past is unlikely to be available to growers following changes in EU legislation.

Technical Summary

Nematodes are economic, agricultural pests. They cause crop damage both directly and as viral vectors. Plant parasitic nematodes are classified as either sedentary e.g. Globodera, Heterodera species and the root knot nematodes, Meloidogyne species or migratory e.g. trichodorids. The species will be affected differently by climate change.
Several climate models predict increased temperatures in the UK by 2.4 - 4 oC and altered rainfall patterns with summers predicted to be drier by 30%. Climate change could result in increased economic damage caused by nematodes that are already prevalent in the UK eg. Globodera pallida and Heterodera schachtii. Climate change may also cause nematode species that are prevalent, but infrequently damaging in the UK, to become important agronomic pests e.g. H. avenae. H. avenae is normally under natural control from fungi but this suppression is reduced in dry summers. Changes in rainfall will also impact on those free-living nematodes that attack plants, e.g. trichodorids and longidorids. Increased temperatures could also lead to a greater threat in the UK from alien nematode species such as Meloidogyne species.
In this work, nematologists will collect the biological information necessary for a climate change modeller to integrate the new information with that already available to predict increased risks from nematode pests of UK agriculture as climate change continues. Simulation models of UK nematode populations will be developed and tested using primary data relating soil temperature and moisture to nematode development, multiplication rates and crop damage. The model will be refined and tested using secondary biological data prior to being used with the UKCP09 climate data to project the risk of future nematode occurrence. Resolution will be to 25km2 and be related to soil type. The insights gained will be used to develop pest management strategies to mitigate the impact of changes in nematode pest status.

Planned Impact

The project will be relevant to, and have impact within, a number of key areas.
1. UK growers. The application is supported by the Potato Council, the Home Grown Cereals Authority and the British Beet Research Organisation (See letters of support). The programme also benefits from collaboration with ADAS. This indicates that the research has direct application to these strategic sectors.
Knowledge of the impact of climate change will be important for all aspects of the commercial agricultural sector - both for seed and ware crop producers. The Potato Council estimate the UK potato production, processing and retail market has an annual value of c. £3 billion. The research will, in the long term, support potato producers. The research looks at the impact of climate change on both sedentary and free living pathogens of this crop including those that act as viral vectors. Aspects of the project that focus on cereal and beet cyst nematodes support the other sectors of the agricultural community that could be heavily impacted by increased nematode problems as a result of climate change.
Nematode pests cause decline in agricultural output, for example the prevalence of G. pallida has contributed to a decline in the UK potato crop of 11.9% between 1999 and 2003. This is a larger fall than that of other major EU producers that lack this pest. This work will establish the likelihood of further impact of this and other emerging pests to the industry and thereby facilitate remedial actions.
2. Supermarkets. The major supermarkets value supply from UK growers. The outputs of the project will help plan and ensure that delivery of home grown produce is available to the consumer.
3. Policy-makers. DEFRA and The Scottish Government (RERAD) must implement the EU's amendment of Directive 91/414/EEC which seeks to reduce use of crop protection chemicals in EU agriculture. The Directive involves the abrupt or gradual withdrawal of pesticides from the UK market. DEFRA and RERAD must aso support an EU Directive specifically aimed at potato cyst nematodes (2007/33/EC) that came into force in July 2010. The research will describe the potential increase in the economic impact of existing pests and the possible emergence of new nematode problems - as well as diseases caused by viral transmission by nematodes. This information will be central to policy makers to restrict the spread of new nematode threats and assess future pesticide needs.
4. General Public. The UK population consumes nationally grown crops. The crops are essential to maintain food prices. Import of many crops is simply not viable due to potential damage of the commodity in transit e.g. potatoes. The work will inform biotechnology and seed companies, growers and producers to ensure the economic delivery of our crops into the future, and thus ensure food security.
5: Environment. Highlighting the potential impact of nematodes as a result of climate change will ensure that a coordinated approach can be taken to the use of land for agriculture. Knowing the likely impact of pests in locations where crops could be grown will allow the optimal use of land and safeguard biodiversity.
 
Description The potato cyst nematodes Globodera pallida and G. rostochiensis are economically important plant pathogens causing losses to UK potato harvests estimated at £50m/ year. Implications of climate change on their future pest status have not been fully considered. We reported growth of female G. pallida and G. rostochiensis over the range 15 to 25 °C. Females per plant and their fecundity declined progressively with temperatures above 17.5 °C for G. pallida, whilst females per plant were optimal between 17.5 and 22.5 ºC for G. rostochiensis. Relative reproductive success with temperature was confirmed on two potato cultivars infected with either species at 15, 22.5 and 25 ºC. The reduced reproductive success of G. pallida at 22.5 °C relative to 15 °C was also recorded for a further seven host cultivars studied. The differences in optimal temperatures for reproductive success may relate to known differences in the altitude of their regions of origin in the Andes. Exposure of G. pallida to a diurnal temperature stress for one week during female growth significantly suppressed subsequent growth for one week at 17.5 °C but had no effect on G. rostochiensis. However, after two weeks of recovery female size was not significantly different from that for the control treatment. Future soil temperatures were simulated for medium and high emissions scenarios and combined with nematode growth data to project future implications of climate change for the two species. Increased soil temperatures associated with climate change may reduce the pest status of G. pallida but benefit G. rostochiensis especially in southern UK. We conclude that plant breeders may be able to exploit the thermal limits of G. pallida by developing potato cultivars able to grow under future warm summer conditions. Existing widely deployed resistance to G. rostochiensis is an important characteristic to retain for new potato cultivars.
Exploitation Route The work has been used to update predictive tools available to the industry as part of our SARIC funded research. See Narrative Impact
Sectors Agriculture, Food and Drink

 
Description We have used the output from the project as a component of our SARIC funded work, "Development of a PCN population advisory tool that provides robust advice and management". That work is a collaboration with industry, Barworth Agriculture, responding to the call from AHDB Potatoes to improve the potato cyst nematode (PCN) population advisory tool to overcome issues that relate to accuracy of yield benefits from chemical control and tolerance values together with a lack of input in relation to crop rotation, biofumigation and trap cropping.
First Year Of Impact 2017
Sector Agriculture, Food and Drink
Impact Types Economic

 
Description SARIC Sustainable Agriculture and Innovation
Amount £167,601 (GBP)
Funding ID NE/P00797X/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 07/2017 
End 02/2019
 
Description Discovery Zone 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact The whole research group was involved in preparing and carrying out an activity-based display at the "Discovery Zone" event for local schools held at the University of Leeds. The event took place over 2 days and more than four hundred school children from Key Stages 2 and 3 engaged with the interactive exhibit "Getting to the root of the matter". We saw over 490 pupils in total - around 260 primary school children, and 230 secondary school children. Age appropriate activities and information relating to crop plants, the importance of roots and root pests and diseases were provided in small group sessions.
Year(s) Of Engagement Activity 2016,2017,2018
 
Description NFU meeting (Stoneleigh) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presentations allowed decisions to be made with respect to new biotechnological options

NFU had information to help set national priorities
Year(s) Of Engagement Activity 2013
 
Description Nufarm UK Ltd 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentations allowed decisions to be made with respect to new biotechnological options

The company had information on which to base commercial decisions.
Year(s) Of Engagement Activity 2013
 
Description University Open Days 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The work undertaken by the research team in developing nematode resistant crops was demonstrated to visitors. Visitors were engaged in discussions about the work and GM technology in general. Postgraduate students, postdocs and technicians associated with the grants all took part in either preparing or demonstrating the events.

Prospective students encouraged to apply for courses with an applied biology focus
Year(s) Of Engagement Activity 2009,2010,2011,2012,2013