Written evidence submitted by the Game & Wildlife Conservation Trust (INS0026)

GWCT response to Science and Technology Committee’s inquiry into insect decline and UK food security – 28th April 2023

The GWCT[1] welcomes the opportunity to contribute evidence to this inquiry.  We are a leading UK charity conducting conservation science to enhance the British countryside for public benefit.  We have conducted research on farmland wildlife since the late 1960s and this has included ecological studies of individual species, habitats, systems, and long-term changes. Of relevance to this inquiry is the research we have undertaken on, for example, the ability of predatory insects to control outbreaks of pest insects in cereals and the role of Integrated Pest Management (IPM), developing and improving agri-environment scheme options including insect-rich habitats, the role of pollination in crop yields and our long-term Sussex Study (https://www.gwct.org.uk/research/long-term-monitoring/sussex-study/) which has measured the impact of changes in farming on the fauna and flora of arable land since 1968 (insects from 1970). These studies are complemented by the research and practice at our demonstration farm in Leicestershire, the Allerton project Projects | The Allerton Project (allertontrust.org.uk).

Summary of key points

• The long-term trends provided by databases such as the Sussex Study indicate that past agricultural practices and climate change are continuing to impact insect numbers despite an overall reduction in the use of agricultural pesticides from 2004; although usage has plateaued recently.
• Insect decline will only be reversed if all possible impacts are addressed, not just a reduction in insecticide/pesticide use.
• Whilst some agri-environment scheme options benefit invertebrates by addressing their habitat requirements, success is being thwarted by the reduced population of many species, the lack of scale of habitat provision and that many options were not specifically designed for insects.
• Management actions such as conservation tillage as opposed to ploughing also need to be encouraged and supported.
• The focus on pollination services, whilst important for the sustainable production of some crops (not all are insect pollinated), is perhaps detracting from the need to encourage farmers to incorporate habitat within the farm that supports beneficial insects i.e. those that are natural pest predators.  This is an important part of the Integrated Pest Management approach.  That said policy needs to focus not just on beneficials and pollinators but all insects given broader food chain/web interactions.
• Whilst the Voluntary Initiative, the industry-led programme promoting sustainable production, has had a significant role in encouraging changes in farmer behaviour through best practice advice and peer-to-peer learning, taking the conservation of invertebrates to the next level will require government investment in conservation measures (both habitat and cultivation methods) and the research and development of disease-resistant crops and alternative biological control methods to encourage the agrochemical industry in the direction needed.

Please see list of GWCT science papers relevant to this inquiry at the end (from page 11) as well as referenced foot notes.

Q1. The current evidence base for insect abundance in the UK, and the gaps in scientific understanding that require further research;

There are a many different surveys, concentrating on individual taxa groups, so in this response we will concentrate on the outcomes from our Sussex Study and Allerton Project (Loddington) databases. Long-term surveys designed to monitor pests of agriculture are also undertaken by Rothamsted (Rothamsted Insect Suction Survey (RIS)).  In general results are similar.

Long-term surveys undertaken at Rothamsted and our own long-term datasets provide better quality data as they are based upon sampling conducted in the same location every year, for a much longer time period (for example insect sampling on our Sussex Study started in 1970 and insect counts at the Allerton Project, Loddington, began in 1992). In addition, our studies use a method that measures abundance rather than activity (we use a DVAC (Dietrick vacuum suction trap) to sample invertebrates) and includes identification of the insects, rather than just biomass, whilst also recording additional information such as crop type, crop disease, arable flora, pesticide use and farmland birds (grey partridge). 

That said there is consensus that insect populations are in decline, particularly specialist species.  We are in the process of summarising the overall trends in invertebrate abundance over the 50 years of the Sussex Study. We have found that overall invertebrate abundance has declined by 37% from 1970 to 2019. Most declines happened in the 1970s, as crop management intensified, with increased declines from 2010. In terms of specific orders of invertebrates:

• Symphyta, Lepidoptera & Neuroptera have increased by 26% (incidentally numbers of caterpillars held up through the 1980s and 1990s where traditional rotations were maintained);
• Chrysomelidae & Curculionidae and Non-aphid Hemiptera have remained stable;
• Araneae & Opiliones have declined by 32%;
• Aphididae have declined by 57%; and,
• Carabidae & Elateridae have declined by 76%.[2]

Collembola (springtails) was the most abundant taxa in our samples.  If these are omitted then overall abundance declined by 48%.

Whilst our data has identified a significant decline in aphid abundance, the long-term trend in aphids from the RIS showed that overall numbers appeared to be in a steady state, with a non-significant decline of −7.6%[3].  This may be accounted for by the fact that our surveys are in crop and those aphids regarded as agricultural pests have exhibited the steepest declines[4]; for example GWCT data showed that aphids were the only group whose abundance was negatively associated with neonicotinoid seed dressings[5], although some research suggests that warming temperatures may

benefit some aphids species in some places[6].

There was no detectable change in pollinators as a group.  As for aphids, it is worth pointing out that the emphasis of the monitoring is on chick food insects and so sampling is within the cereal crop – this will not sample bees and other pollinators that are attracted to floral resources. 

Analysis of the invertebrate data from 1970 – 2011 found that many of the most common taxa were more able to cope with extreme weather events and consequently recovered to their former trends within a year. This suggests that, in general, the perturbation cycle of farmed environments (the cereal habitat is one that lasts for less than a year in most cases) favours adaptable species. (It should be noted that this analysis missed 2012, the year with the most extreme precipitation event in the over 50 years of the Sussex Study).  It is worth bearing in mind that the ability to recover from an extreme weather event may not reflect the ability of insects to recover from year upon year of insecticide use (see answer to Q2).

The focus at Allerton is on farmland bird recovery, where provision of invertebrate food in summer is important, with the abundance of invertebrates that benefit crop production through their roles in pollination and crop pest predation also of interest.   Consequently, invertebrate abundance data also includes non-cropped, semi-natural habitats such as hedgerows, grass banks and cover crops where results suggest there is a higher abundance of insects.   However, despite further improvements in the habitat and the way we farm, there are still 17% fewer birds at Allerton than twenty years ago pointing to factors outside our control. 

The following chart demonstrates the winners and losers from our research into the relationship between chick-food insects[7] and pesticides at our Sussex and Allerton project (Loddington) sites.  This also shows that for some invertebrate groups (namely caterpillars, spiders & harvestmen and the grey partridge chick food index (CFI)), the effects of insecticide use are the same even though at Loddington only pyrethroids and pirimicarb insecticides were used.

These results reinforce earlier results from the Sussex Study which identified that spring/summer pesticide applications are more damaging than autumn ones.

Recent research has also highlighted that focussing only on bees as pollinators may distort policy outcomes. Moths are efficient night-time pollinators[8] whilst current conservation policies and agri-environment schemes demonstrate taxonomic bias favouring Lepidopterans (moths and butterflies) over Coleopterans (beetles) and Hymenopterans (bees, ants, wasps)[9]. In samples from cereal crops pollinators are represented by members of the Thysanoptera, Lepidoptera (mainly moths in cereals), Symphyta, Nitidulidae and Syrphidae.

GWCT data on moth abundance at the Allerton project suggests that active management through the provision of habitat with varied plant (host) species, such as wildflower margins, beetle banks, agroforestry and grass margins, is beneficial.  We have monitored moths since 1995 using a Rothamsted light trap as part of the national monitoring network. This network of traps reveals a 33% decline nationally in the abundance of macro-moths between 1968 and 2017.  However, at the Allerton Project overall abundance of macro-moths was 36% higher in 2019 than it was in 1995[10]. In addition, we have compared our results with a nearby monitoring site on a nature reserve at Rutland Water.  In contrast to the increases seen at Allerton, the results from the Rutland Water site are in line with the declines seen in the national data.  Given that some of the causes of insect declines such as insecticides will not have been used and that the habitat will have remained unchanged (preserved), the differences suggest other factors such as climate change are involved and that active management is need to support existing populations whilst also benefitting new species due to range expansion.

The reasons for insect declines are likely to be many (see answer to Q2) and so it is important that interpretation of these datasets when designing policy acknowledges the interrelated nature of the (known) factors affecting insect populations.

Further research is needed into the impacts of climate change and other factors such as land-use changes and invasive species[11] on insect assemblages and population levels in different ecosystems or under different land managements.  Whilst agri-environment schemes have sought to redress the changes in the farming system that have affected habitat availability (see also answers to Questions 3 and 5 below given we are concerned that current endeavours are insufficient) and the switch to minimum tillage will foster a much richer insect community and provide benefits up the food chain[12], the long-term changes in weather and an increased frequency of extreme weather events predicted under current IPCC climate change models are likely to continue to affect insect populations.  Climate change will affect insects and pollinators by causing changes in flowering times[13] and may be changing our insect assemblage. Analysis of invertebrate data from our long-term Sussex Study has shown that some pollinators (such as Thysanoptera, Lepidoptera (mainly moths), Symphyta, Nitidulidae, Syrphidae) and some predator numbers are increasing due to increases in temperature, while other plant-feeding insects show negative relationships with increasing temperature.  The data from Allerton has also indicated that annual drivers of variation such as weather conditions are acting in synchrony across habitats/land uses.

In addition, research has shown that pollinators are affected by air pollutants[14].

Q2. The effects of pesticides, such as neonicotinoids or other agricultural control methods on insects including pollinators and their impact on UK food security;

Whilst pesticide use has clearly affected insect populations, there are other factors in the decline and changes in insect assemblage, such as block cropping (which impacts the less mobile species including many predatory insects such as carabid beetles), the loss of mixed farming and soil management (ploughing generally detrimental), which must not be overlooked when designing policy. In addition, the abundance of many taxa that occupy arable habitats can also be affected by cropping, field size and weather. All of the changes are interrelated and have not happened in isolation, making it difficult to identify any one significant impact on the flora and fauna of farmland that we have witnessed over the past half a century and therefore the solution to reversing their decline.

However, the question specifically considers the effect of pesticides. Use of insecticides, fungicides and herbicides increased between 1970 and 2004 on the Sussex Study area (pesticide use there broadly matches use across the UK in similar crops) and then stabilised from 2005 due to changes in cropping[15].  All three types can have an impact on insects. Herbicides by removing the weeds upon which many plant feeding insects depend; fungicides by reducing fungi that some insects also feed on (e.g. Tachyporus species) as well as directly affecting some insects[16],[17]; and, of course, insecticides, even those considered to be selective such as pirimicarb, which is “selective” for aphids, can have an impact[18] (Moreby et al 2001) although not as bad as some[19].  The cumulative effect of total use within a growing season on the health, survival and performance of pollinators is unknown[20]  - and therefore on other insects too.  In addition, the relative proportions of the use of pesticides changes over time due to changes in approvals and the introduction of new products.  For example the recent ban on neonicotinoids resulting in the adoption of other insecticides such as sulfoxaflor[21] and foliar applications of pyrethroids which GWCT research suggested are more of a threat to the abundance of chick-food invertebrates than the use of neonicotinoid seed treatments, in a cereal ecosystem[22]. 

As stated above data from the Sussex Study has revealed declines of 37% overall in the total number of invertebrates, with most of the declines happening in the 1970s.  However, this varies by taxa with insects that are chick-food for declining farmland birds declining by up to 72% from 1970 to 2015, with 45% of invertebrate groups significantly reduced.  Analysis on a field-by-field basis indicates that it is insecticide use that is responsible for lower insect numbers, especially those that provide food resources for declining farmland birds. In general, our research, which, to remind you, focusses on those groups of invertebrates that form the food resource for farmland birds, has shown that:

•                                                                                                                  aphid abundance was negatively affected by neonicotinoid seed dressings;
•                                                                                                                  foliar insecticide use had a negative effect overall which ‘carried-over’ into the following year, with the consequences lasting beyond the year in which they were first used;
•                                                                                                                  between 1970-1990 there was an increase in fungicide applications, the efficacy of herbicides applied and the number of foliar insecticide applications with a subsequent plateauing; and,
•                                                                                                                  insecticide applications in cereals are mainly used now in the autumn to control aphids that carry BYDV (Barley Yellow Dwarf Virus). (There are other approaches to reducing the impact of BYDV which are discussed in answer to Q5). However, farmers are actively questioning whether these “insurance” spays are still required in the face of declining aphid numbers, particularly where the drilling of cereal crops is delayed in the autumn as part of a blackgrass control strategy.

These impacts could be minimised by changing behaviour or the loss of an active ingredient.  For example, BYDV insecticide applications could be minimised through the use of direct drilling, later sowing, BYDV-resistant varieties and IPM (see answer to Q5) and the loss of Chlorothalonil as an active ingredient in fungicides, which had been correlated with negative effects on bee colonies, may go some way to addressing impacts of this group of pesticides.

The effects of spraying frequency also need to be considered.  Evidence from the Sussex Study shows a carry-over effect into following years[23],[24] and therefore we may expect that the more frequently insecticides are applied to a field, the less chance there is of recovery. Previous work that modelled the effect of insecticide treatment on sawfly numbers (Symphyta) indicated that it would take seven years to recover numbers following treatment[25].

Importantly, in the Sussex Study two of the key groups of invertebrates that provide Integrated Pest Management (spiders and beetles) were most affected by pesticides. For some of these taxa, the sharpest declines in abundance occurred in the 1970s, and we know from previous analyses that the insecticides used in this period were particularly harmful (e.g. organophosphates[26] ). Whilst farmers are now more aware of the role of pest natural enemies and the impacts of insecticides, insect monitoring data is still suggesting that populations are being negatively affected despite stabilisation in their use over the past two decades.

Pollinators are vital to food production and sustainability, and it is imperative that we find alternatives to pesticide use over time such as the greater use of Integrated Pest Management (IPM). GWCT work maximising natural pest-predator relationships through habitat provision could be used to create measures to aid farmers in combating pest/disease problems.  For example, our work has shown that predators that fly are more effective at reducing the number of cereal aphids than ground-active ones and that if a long stubble is left when harvesting cereal crops, this provides spiders with the necessary structure for them to weave their webs and collect their prey of aphids.  This one example demonstrates that it is likely to be a suite of measures that we will need to use to replace the use of pesticides and seed-treatments as well as funding initiatives to support their introduction.  Relying on the industry alone has so far failed.

Understanding the impact of these declines on food security is important as it has been estimated that 85% of European food crop species are dependent to some extent on insect pollination.  The 2019 National Pollinator Strategy evidence update identified that pollination services are dependent on insect numbers and suggested that pollination services to crops and wild plants have also decline in the long term (inconclusive). The GWCT looked at the impact of reduced pollination on yields of sunflowers, oilseed rape (OSR), pears and pumpkins, across six European countries.  Our study showed that inadequate pollination reduced crop yield by a relatively moderate 2.8% but that this differed by crop type and location and consequently may be economically important at some sites.  In addition, the level of pollination was not related to the number of visits from pollinators.  As well as the availability of pollinators, alternative pollination mechanisms mean that some crops are not entirely reliant on insects e.g., oilseed rape can be cross-pollinated by wind.  Different pollinating species may vary in how effectively they pollinate a crop. For example, honeybees may be relatively inefficient pollinators of sunflowers, either through visiting only a few florets on each flower head (of which there can be thousands), or through not making robust enough contact with the correct areas of the floret to effectively pollinate each one on each visit.

Q3. The extent that biodiversity initiatives, such as creating reservoir populations, are addressing insect decline and whether there is sufficient co-ordination with the UK food system;

The GWCT remains concerned that current initiatives are insufficient to address insect decline. The long-term trends from the Sussex Study indicate that invertebrate declines have continued since some of the initial work on biodiversity initiatives, indicating that there is also a need to consider a larger deficit in insect abundance.

The Sussex Study and Allerton invertebrate monitoring provide two key and unique datasets, as they monitor invertebrate abundance in the crops themselves – something that most other long-term invertebrate monitoring in the UK does not do. This is important as part of the solution to making farming more sustainable (by reducing inorganic inputs such as pesticides) is the support of beneficial invertebrates within the crop to provide natural pest control (or IPM).

It is worth noting at this point that The Voluntary Initiative, the industry-led programme that supports the responsible use of pesticides using IPM, provides advice to farmers on combining productivity with sustainable practices such as IPM and monitors the adoption of IPM techniques in Combinable & Broad Acre, Grassland and Specialist Horticultural Crops (Voluntary Initiative).

We consider alternative policy options in answer to Q5.  Here we outline evidence that suggests that whilst AES options may aid some invertebrates, the functional objective of the invertebrate (e.g. pollination or IPM) should be considered when designing schemes at both the farm and landscape scale.  In addition, new research is needed in the face of continuing insect decline to determine how best to manage AES options and the best mixes to use in wild bird cover/wildflower options. This work needs to be better resourced and take place at locations across the UK.

Both pollination and IPM have crop production benefits and are an important consideration in the sustainability of UK food production.  It is widely considered that pollination services may be worsening due to declines in farmland pollinators but the consequences of this for yields are uncertain. GWCT research has suggested that yields in oil seed rape, for example, are not severely limited by reduced numbers of insect visits[27].

Insect pollinated cropland only accounts for c20% of total UK cropland (2007 estimate), relating to orchard and soft fruits, vegetables and some biofuels (not all crops fundamental to our food system are insect pollinated; cereals are wind pollinated for example.) This service is worth about £500 million each year in the UK[28]. This pollination service is provided by wild pollinators such as bumblebees, solitary bees, hoverflies and butterflies and managed bee species including the honey bee. Current evidence, however, shows that many wild and managed pollinators are in widespread decline and this could have serious implications for the productivity of insect pollinated crops and food security in the UK.

Current agri-environment scheme (AES) initiatives that support biodiversity were largely developed to aid avian conservation – i.e., to provide either invertebrate food for chicks, seeds for winter food or nesting cover.  The GWCT developed many of these options, including conservation headlands, beetle banks, wild bird covers/wildflower mixes and cultivated arable margins, which also provide for invertebrates and arable flora in the farmed environment. Not surprisingly studies have shown that some AES options designed for avian conservation support invertebrates given that they form the diet of many farmland birds e.g. yellowhammer[29], tree sparrow[30], and songbirds[31]  with other ‘non-targets’ such as pollinators benefitting from the mixed-plant communities that comprise wild bird cover strips[32],[33].  

These effects can vary by spatial scale and management approach with, for example, upland grasslands (both improved and semi-improved) managed in accordance with AES demonstrating a benefit to multi-taxa invertebrate abundance[34] whilst aerial insects responded to AES at the landscape scale given their highly mobile nature[35].  In the farmed landscape, GWCT research has highlighted the need for both annually cultivated and floristically enhanced grass margins (perennial) habitats to be provided where arable pollinator conservation is a priority[36].

We are concerned that the focus on avian conservation in the development and design of AES options means that the scale of AES in the environment is too small to make a difference to a range of invertebrates.

Some insect populations can take time to recover, as many only have one generation per year. For example, GWCT research has shown that it can take sawflies 7 years to recover following insecticide applications[37]. Consequently, it is important that the invertebrate populations remain unaffected if they are to rebuild their populations, so unsprayed areas are needed across the landscape.  In addition, for sawflies the loss of undersowing is limiting their recovery. Undersown fields will provide a more diverse “weed” population due to the use of herbicides that have a limited scope of effectiveness. They are also not ploughed, with the grass crop (ley) allowed to develop after the cereal is harvested. This reinforces the point above that it is the management of the land that can impact on invertebrate abundance as much as the provision of suitable habitat.

Connected to this is the need for farming to move away from chemical means of control, which has so often resulted in negative effects on non-targets. Investment into resistant crop varieties is key; an opportunity provided by the recent Genetic Technology (Precision Breeding) Act. Funding for this needs to come from governmental sources. It is unlikely that industrial elements of agriculture will see much of the funding needed as a good business investment – at least until it is closer to a final product.

Q4. Whether the threat to UK food security from insect decline receives sufficient cross-government priority; and

Given the continuing decline in insect numbers and the lack, to date, of policy initiatives focussed on insect recovery and accompanied by investment to move away from pesticide-led farming, we suggest that this is a hurdle.  Defra is the lead department and has spearheaded the development of agri-environment schemes to reverse biodiversity declines but changes to schemes, their complexity and prescriptive nature plus lack of sufficient monetary investment has resulted in variable levels of farmer involvement.  A continuous, longer-term approach is needed, and this requires broader Government support, including by the Treasury which needs to acknowledge how important farmers/land managers, the farmed environment and food security are to UK nature.  The advent of natural capital is helping this cause but the lack of promotion by Government of some initiatives such as IPM means that some areas of the marketplace lack investment.

Q5. Additional policy initiatives and solutions needed in the UK and internationally to reduce and reverse the trends in insect decline.

As suggested above whilst existing AES options are aiding the situation, data from our Sussex Study suggests that these are unlikely to be sufficient.  What is needed are better designed mixes, more attention given to the management both of the options and the surrounding farmland (e.g. tillage), more focus on beneficial insects and reduced use of insecticides, and more attractive payment rates for AES options.     We discuss these in turn.

GWCT research has identified the importance of the constituents of mixes, often at variance with current AES mixes, and the need for the provision of both annual and perennial habitats given that they attract different insect taxa.  For example, the National Pollinator Strategy review in 2019 stated that “The inclusion of particular plant species to sown wildflower strips would enhance their support of pollinators with more specialist diets”[38]. GWCT research has identified species that are attractive to solitary bees and bumblebees[39].  Currently the pollinator mixes often contain high levels of clovers which are attractive to bumblebees but not solitary bees.  Incidentally there was only one species that was attractive to both these types of bees, emphasising the need to identify the goal to ensure correct actions are taken. We were also lead for the BEESPOKE project (an EU Interreg North Sea Region Programme Updates & News, Interreg VB North Sea Region Programme) which aims to encourage farmers to conserve invertebrates through demonstrating their value to crop production.  This included improved knowledge about the best pollinators for crops and the development of seed mixes tailored to their support such as a soft fruit wildflower mix and a novel wildflower seed mix target at both wild bees and other pollinators. 

We have also referenced above the need to consider management approaches such as tillage in the conservation of invertebrates.  The best pest control options should rely on the integration of alternative methods such as biological (IPM) and mechanical (conservation tillage).  The interaction between tillage and pests is unlikely to lead to yield losses of economic consequence[40].

This can also tie in with reducing insecticide applications.  There is some evidence that direct drilling makes it more difficult for aphids to "attack" young cereal plants and it is associated with an increase in spiders and other predatory insects that provide integrated pest management (IPM). In addition, early autumn sown cereals - those sown in early to mid-September - are a target for the aphids that spread BYDV in October through to early December and so sowing later is likely to reduce aphid attack as a hard frost will kill them and stop BYDV spread.

In tandem with focussing on pollination services, Defra needs to concentrate on maximising the benefits of AES options for beneficial insects (natural pest predators) in support of IPM to encourage farmers to move further down this track.  The Allerton Project has been a pioneer in IPM through work on looking at ways of increasing the utilisation of beneficial crop pest predators in farmland settings e.g., the beetle bank habitat was developed at Allerton in the early 1980s.  Beetle banks are man-made earth banks covered in tussocky grasses that are ~ 0.4m high and constructed across the middle of large fields or at the margins.  They act as overwinter habitat for predatory insects and spiders.  Densities of such species can reach over 1000 individuals/m2 and the idea is that they move into the neighbouring crop to reduce pest levels[41], for example aphids in cereals[42]. 

Encouraging farmers to focus on encouraging beneficial insects (natural pest predators) can reduce the chance of pests establishing and proliferating in crops and consequently causing economic damage. However, it is not a quick fix solution as it relies on building up a diverse range and abundance of natural enemies through appropriate habitat provision to deliver right types of natural enemies, at the right time and in the right place. This ensures that when pests do arrive there are sufficient natural enemies of the type that can control the pest in question.   This can be achieved by following the SAFE approach of:

• Shelter – For overwintering/dormancy and periods of inactivity/breeding
• Alternative Prey – For when pests are not present
• Floral Resources – For energy and nutrients
• Environment – Appropriate for survival, preferred vegetation cover and insecticide-free.

More funding is needed to improve the provision of habitats for insects in farmland. For AES payments this needs to go beyond income foregone and provide for an element of ‘profit’. Advice on how best to recover insects needs to be provided freely to farmers and this will need ongoing research into the best mixes, management, etc. to continually improve that provision. This should be seen as counteracting the effects of the continual improvement in agronomy to produce sterile, productive crops. Agricultural intensification has become a problem because we have not intensified our provision for nature.

GWCT advises a number of actions to encourage insects (see below).  These are designed to address the interrelated factors affecting insect numbers discussed above.  Government policy needs to consider insect declines in a similarly holistic way rather than focus on individual factors.  In addition, many of the actions below provide additional ecosystem services such as improving soil health and biota which support food security.

GWCT advice is:

1. Follow IPM guidelines and avoid using insecticides whenever possible.  Don’t spray headlands.
2. Don’t be too tidy. Try to tolerate a few more weeds in crops.
3. Establish new habitats that are insect-rich, e.g. beetle banks, nectar-flower mixes, wild bird seed, herb rich grassland, conservation headlands, cultivated arable margins and ponds.
4. Only cut hedges every two years to allow flowering and berry production.
5. Avoid contaminating the hedge base with fertilizer and pesticides.
6. Adopt minimum tillage and return crop residues to the soil.
7. Grow alternative livestock forage – legumes, especially sainfoin and whole crop silage.

Game & Wildlife Conservation Trust

28 April 2023

GWCT scientific papers related to invertebrate conservation (not exhaustive):

Stoate, C. (2022). Farming with the Environment: Thirty Years of the Allerton Project Research. Taylor & Francis, Abingdon: 1-217. Taylor & Francis, Abingdon.

Nichols, R.N., Wood, T.J., Holland, J.M., & Goulson, D. (2022). Role of management in the long-term provision of floral resources on farmland. Agriculture, Ecosystems & Environment, 335(108004): 1-11.

Holland, J.M., Moreby, S.J., Ewald, J.A., Buner, F., Turner, H., & Ness, E. (2022) Where have all the insects gone? GWCT 2021 Annual Review pp. 40-43.

Ewald, J.A., Sotherton, N. W., & Aebischer, N.J. (2020). Invertebrate Trends in an Arable Environment: Long-term Changes from the Sussex Study in Southern England. In: Hurford, C., Wilson, P.J. & Storkey, J. (eds) The Changing Status of Arable Habitats in Europe - a Nature Conservation Review: 157-172. Springer, London.

Holland, J. M, Jeanneret, P., Moonen, A.-C., Van der Werf, W, Rossing, W. A. H., Antichi, D., Entling, M. H., Giffard, B., Helsen, H., Szalai, M., Rega, C., Gilbert, C. & Veromann, E. (2020). Approaches to Identify the Value of Seminatural Habitats for Conservation Biological Control. Insects, 11(195): 1-11.

Sotherton, N.W. (2019). The Crop Headland. Managing the Edges of Crops to Support Wildlife. In: Dover, J.W. (ed.) The Ecology of Hedgerows and Field Margins: 110-122. Routledge, Abingdon.

Fusser, M.S., Holland, J.M., Jeanneret, P., Pfister, S.C., Entling, M.H., & Schirmel, J. (2018). Interactive effects of local and landscape factors on farmland carabids. Agricultural and Forest Entomology, 20: 549-557

Wood, T.J., Holland, J.M. & Goulson, D. (2017). Providing foraging resources for solitary bees on farmland: current schemes for pollinators benefit a limited suite of species. Journal of Applied Ecology, 54: 323-333.

Ewald, J.A., Wheatley, C.J., Aebischer, N.J., Duffield, S.J., & Heaver, D. (2016). Investigation of the Impact of Changes in Pesticide Use on Invertebrate Populations. Natural England Commissioned Report, NECR182. Natural England, York.

Holland, J.M., Bianchi, F.J.J.A., Entling, M.H., Moonen, A.-C., Smith, B.M. & Jeanneret, P. (2016). Structure, function and management of semi-natural habitats for conservation biological control: a review of European studies. Pest Management Science, 72: 1638-1651.

Holland, J.M., Smith, B.M., Storkey, J., Lutman, P.J.W. & Aebischer, N.J. (2015). Managing habitats on English farmland for insect pollinator conservation. Biological Conservation, 182: 215-222.

Ewald, J.A., Aebischer, N.J., Moreby, S.J., & Potts, G.R. (2015). Changes in the cereal ecosystem on the South Downs of southern England, over the past 45 years. Aspects of Applied Biology, 128: 11-19.

Holland, J.M., Storkey, J., Lutman, P.J.W., Birkett, T.C., Simper, J.N. & Aebischer, N.J. (2014). Utilisation of agri-environment scheme habitats to enhance invertebrate ecosystem service providers. Agriculture, Ecosystems and Environment, 183: 103-109.

Henderson, I.G., Holland, J.M., Storkey, J., Lutman, P.J.W., Orson, J. & Simper, J.N. (2012). Effects of the proportion and spatial arrangement of un-cropped land on breeding bird abundance in arable rotations. Journal of Applied Ecology, 49: 883-891.

Holland, J.M., Oaten, H., Moreby, S.J., Birkett, T.C., Simper, J.N., Southway, S.E. & Smith, B.M. (2012). Agri-environment scheme enhancing ecosystem services: A demonstration of improved biological control in cereal crops. Agriculture, Ecosystems and Environment, 155: 147-152.

Smith, B.M., Holland, J.M., Jones, N.E., Moreby, S.J., Morris, A.J. & Southway, S.E. (2009). Enhancing invertebrate food resources for skylarks in cereal ecosystems: how useful are in-crop agri-environment scheme management options? Journal of Applied Ecology, 46: 692-702.

Ewald, J.A., Wheatley, C.J., Aebischer, N.J., Moreby, S.J., Duffield, S.J., Crick, H.Q.P., & Morecroft, M.B. (2015). Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years. Global Change Biology, 21: 3931-3950.

Ewald, J.A., Wheatley, C.J., Aebischer, N.J, Duffield, S., Morecroft, M. & Crick, H.P.Q (2014). Cereal invertebrates, extreme events and long-term trends in climate. Natural England Commissioned Report NECR135.

Potts, G.R., Ewald, J.A., & Aebischer, N.J. (2010). Long-term changes in the flora of the cereal ecosystem on the Sussex Downs, England, focusing on the years 1968-2005. Journal of Applied Ecology, 47: 215-226.

Holland, J.M., Birkett, T.C. & Southway, S.E. (2009). Contrasting the farm-scale spatio-temporal dynamics of boundary and field overwintering predatory beetles in arable crops. BioControl, 54: 19-33.

Holland, J.M., Oaten, H., Southway, S.E. & Moreby, S.J. (2008). The effectiveness of field margin enhancement for cereal aphid control by different natural enemy guilds. Biological Control, 47: 71-76.

Holland, J.M. (2007). The potential of agri-environment schemes to enhance biocontrol in arable crops. Aspects of Applied Biology, 81: 127-134.

Game Conservancy (2007) Development of indicator species to measure pesticide impact on farmland wildlife. Report to Defra - PS2313, Defra, London. http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=0&ProjectID=12182

Holland, J.M., Southway, S.E., Birkett, T.C. & Moreby, S.J. (2006). The relative merits of field and boundary habitats for conservation biocontrol. Landscape Management for Functional Biodiversity IOBC wprs Bulletin, 29: 57-60.

Hart, J.D., Milsom, T.P., Fisher, G., Wilkins, V., Moreby, S.J., Murray, A.W.A. & Robertson, P.A. (2006). The relationship between yellowhammer breeding performance, arthropod abundance and insecticide applications on arable farmland. Journal of Applied Ecology, 43: 81-91.

Holland, J.M., Ewald, J.A. & Aebischer, N.J. (2005). Field studies of pesticide effects on terrestrial invertebrates. In: Liess, M., Brown, C., Dohmen, P., Duquesne, S., Hart, A., Heimbach, F., Kreuger, J., Lagadic, L., Maund, S., Reinert, W., Streloke, M. & Tarazona, J.V. (eds) Effects of Pesticides in the Field: 70-73. Society of Environmental Toxicology and Chemistry, Brussels.

Holland, J.M. (2004). The environmental consequences of adopting conservation tillage in Europe: reviewing the evidence. Agriculture, Ecosystems and Environment, 103: 1-25.

Ewald, J.A., Aebischer, N.J., Brickle, N.W., Moreby, S.J., Potts, G.R. & Wakeham-Dawson, A. (2002). Spatial variation in densities of farmland birds in relation to pesticide use and avian food resources. In: Chamberlain, D.E. & Wilson, A. (eds) Avian Landscape Ecology: Pure and Applied Issues in the Large-Scale Ecology of Birds: 305-312. International Association for Landscape Ecology (UK).

Holland, J.M., Southway, S.E., Ewald, J.A., Birkett, T.C., Begbie, M., Hart, J.D., Parrott, D., & Allcock, J. (2002). Invertebrate chick food for farmland birds: spatial and temporal variation in different crops. Aspects of Applied Biology, 67: 27-34.

Ewald, J.A. & Aebischer, N.J. (2000). Trends in pesticide use and efficacy during 26 years of changing agriculture in southern England. Environmental Monitoring and Assessment, 64: 493-529.

Ewald, J.A. & Aebischer, N.J. (1999). Pesticide Use, Avian Food Resources and Bird Densities in Sussex. JNCC Report No. 296, Joint Nature Conservation Committee, Peterborough.

Collins, K.L., Wilcox, A., Chaney, K., Boatman, N.D. & Holland, J.M. (1997). The influence of beetle banks on aphid population predation in winter wheat. Aspects of Applied Biology, 50: 341-346.

Dover, J.W. (1997). Conservation headlands: effects on butterfly distribution and behaviour. Agriculture, Ecosystems and Environment, 63: 31-49.

Holland, J.M. & Thomas, S.R. (1997). Quantifying the impact of polyphagous invertebrate predators in controlling cereal aphids and in preventing wheat yield and quality reductions. Annals of Applied Biology, 131: 375-397.

Aebischer, N.J. (1991). Twenty years of monitoring invertebrates and weeds in cereal fields in Sussex. In: Firbank, L.G., Carter, N., Darbyshire, J.F. & Potts, G.R. (eds) The Ecology of Temperate Cereal Fields: 305-331. Blackwell Scientific Publications, Oxford.

Sotherton, N.W. (1991). Conservation Headlands: a practical combination of intensive cereal farming and conservation. In: Firbank, L.G., Carter, N., Darbyshire, J.F. & Potts, G.R. (eds) Ecology of Temperate Cereal Fields: 373-397. British Ecological Society Symposium, Blackwell Scientific Publications, Oxford.

Aebischer, N.J. (1990). Assessing pesticide effects on non-target invertebrates using long-term monitoring and time-series modelling. Functional Ecology, 4: 369-373.

Potts, G.R. & Vickerman, G.P. (1974). Studies on the cereal ecosystem. In: Macfadyen, A. (ed.) Advances in Ecological Research, 8: 107-197. Academic Press (London) Ltd, London.