crops – Page 2 – Cabot Institute for the Environment blog

In defence of wasps: why squashing them comes with a sting in the tale

Posted on July 25, 2016April 6, 2023 by janet.crompton

Image credit: Trounce

They are one of the most unwelcome signs of summer. Buzzing through beer gardens, attacking innocent picnics, wasps arrive ominously with a sting in their tails. Universally disliked, they are swatted, trapped and cursed. But would a wasp-free world really be a better place?

Despite their poor public image, wasps are incredibly important for the world’s economy and ecosystems. Without them, the planet would be pest-ridden to biblical proportions, with much reduced biodiversity. They are a natural asset of a world dominated by humans, providing us with free services that contribute to our economy, society and ecology.

Wasps, as we know, turn up everywhere. More than 110,000 species have been identified, and it is estimated there are still another 100,000 waiting to be discovered. One recent study described 186 new wasp species in one small corner of Costa Rican rainforest alone. In contrast there are only around 5,400 species of mammals, and 14,000 recorded species of ant.

This huge and diverse assemblage belongs to the order Hymenoptera and is divided into two groups, the Parasitica and the Aculeata. Almost 80,000 species of wasps belong to the Parasitica group, which lay their eggs in or on their prey or plants using elongated tubular organs called ovipositors. The remaining 33,000 species are Aculeates, most of which are predators, and the ones whose ovipositors have been modified through evolution to form a sting.

Both parasitic and predatory wasps have a massive impact on the abundance of arthropods, the largest phylum in the animal kingdom, which includes spiders, mites, insects, and centipedes. They are right at the top of the invertebrate food chain. Through the regulation of both carnivorous and plant-feeding arthropod populations, wasps protect lower invertebrate species and plants. This regulation of populations is arguably their most important role, both ecologically and economically.

Although the majority of wasps lead solitary lives, it is the 1,000 or so species of social wasps which make the biggest impression on insect populations. Social wasp queens share their nests with thousands of offspring workers, who raise upwards of 10,000 sibling larvae during the colony cycle. This means a single nest provides a whopping bang for buck in terms of ecosystem services, killing vast numbers of spiders, millipedes and crop-devouring insects.

Pest control. shutterstock

Many social wasps are generalist predators too, which means they control populations of a wide range of species, but rarely wipe any single species out. This makes them an extremely useful, minimising the need for toxic pesticides, but unlikely to threaten prey biodiversity. It is not yet possible to accurately quantify their huge economic value in this regard, but their diet of agricultural pests such as caterpillars, aphids and whiteflies makes a massive contribution to global food security.

Wasps also play a crucial role in ecosystems as specialist pollinators. The relationship between figs and fig wasps is arguably the most interdependent pollination symbiosis known to man. Without one another, neither the fig nor fig wasp can complete their life-cycle – a textbook example of co-evolution which is estimated to have been ongoing for at least 60m years. Figs are keystone species in tropical regions worldwide – their fruit supports the diets of at least 1,274 mammals and birds. The extinction of fig wasps would therefore be catastrophic in tropical ecosystems.

The birds and the bees … and the wasp

Almost 100 species of orchids are solely reliant on the action of wasps for pollination. The plants mimic the appearance and chemical profile of female wasps, tricking males into attempting to mate with them, so that as the male wasps attempt to copulate with the flower they are loaded with pollen which is then transferred to the next male-seducing orchid. Without the wasp, these orchids would be extinct.

Working wasp. Shutterstock

Wasps also function as generalist pollinators, inadvertently transferring pollen between flowers they visit for nectar collection. One type even provide their larvae with pollen instead of insect prey. These “pollen-wasps” are considered to perform the same ecological roles as bees, pollinating a diverse array of plants. Unfortunately, while bees are credited with contributing at least €100 billion a year to the global economy through their acts of pollination, the works of wasps in the same sector is often ignored.

Even the wasps’ sting could have a positive impact on the human population. Medical researchers are exploring the potential use of biologically active molecules found within wasp venom for cancer therapy. A chemical found in the venom of the tropical social wasp Polybia paulista, has been shown to selectively destroy various types of cancerous cells.

Since they protect our crops, make ecosystems thrive, sustain fruit and flowers, and might help us fight disease, perhaps we should appreciate the wonderful work of wasps before we next swipe at them with a rolled up newspaper. They may be a nuisance on a sunny afternoon – but a world without wasps would be an ecological and economic disaster.

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This blog is written by Cabot Institute member, Seirian Sumner, a Senior Lecturer in Behavioural Biology, University of Bristol and Ryan Brock, MRes candidate, University of Bristol. This article was originally published on The Conversation. Read the original article.

A brief introduction to how Bristol’s plant science might save the world

Posted on April 2, 2014April 19, 2023 by janet.crompton

Global crop yields of wheat and corn are starting to decline, and the latest report from the Intergovernmental Panel on Climate Change (IPCC) suggests things are only going to get worse.

Last year I looked at previous research into what climate change might mean for global crop yields and found that overall crop yields would remain stable but regional declines could prove devastating for certain parts of the world. The definitive new report from the IPCC finds that actually a temperature rise of just 1°C will have negative impacts on the global yields of wheat, rice and maize, the three major crop plants. Food prices could increase by as much as 84% by 2050, with countries in the tropics being much more badly affected than northern Europe and North America.

All over the world, research is underway to find sustainable ways to feed the growing population. Scientists within the Cabot Institute’s Food Security research theme are working on a range of problems that should help us manage the threat that climate change presents.

Improving crop breeding

The average increase in yields of the world’s most important crops is slowing down, which means that supply is not keeping up with demand. Professor Keith Edwards and Dr. Gary Barker are leading UK research into wheat genomes, developing molecular markers linked to economically important traits. These markers are often Single Nucleotide Polymorphisms (SNPs), which are single letter differences in the DNA code. It’s possible to find SNPs linked to areas of the genome associated with disease resistance or increased yield, allowing breeders to rapidly check whether plants have the traits they are looking for.

Wheat is a vital crop for UK agriculture as well as global food security.

Water use in plants

Climate change means that many parts of the world will face extreme weather events like droughts. Clean, fresh water is already an increasingly valuable resource and is predicted to be a major source of global conflict in the future.

Plants produce microscopic pores known as stomata on their leaves and stems, which open to take in carbon dioxide for photosynthesis but close in drought conditions to prevent excess water loss from the plant. Professor Alistair Hetherington’s group looks at the environmental conditions that affect stomatal formation and function, which will help to determine how droughts or higher carbon dioxide levels might affect crop productivity in the future and how we might enhance their water use efficiency.

Professor Claire Grierson’s group are working on root development, another important factor in managing how plants use water. Plants produce elongated root hairs which extend out into the substrate, increasing the root surface area in order to absorb more water and nutrients. If we can understand how root hairs are produced, we may be able to breed plants with even more efficient roots, able to extract enough water from nearly-dry soil in periods of low rainfall.

Each root hair is a single elongated cell that hugely increases a plant’s ability to take up water.

Preventing disease

Mycosphaerella graminicola is a wheat
pathogen that greatly reduces yield,
posing the biggest risk to wheat production worldwide.

A particular concern of climate change is that diseases may spread to new areas or be more destructive than they used to be. Professor Gary Foster and Dr. Andy Bailey are leading research into a variety of fungal and viral plant pathogens, which are responsible for devastating crop yields around the world. They use new molecular techniques to determine exactly how diseases begin and what treatments are effective against them, information that will be vital as plant disease patterns change across the world.

Crop pollination

It is still unclear whether climate change is affecting bees, however some research suggests that flowers requiring pollination are getting out of sync with bees and other pollinators. This might not be a problem for wind-pollinated crops like maize and barley, or self-pollinators like wheat and rice, however most fruits and oil crops rely on pollinators to transfer pollen from plant to plant. Dr. Heather Whitney researches the interaction between plants and their pollinators, particularly focussing on how petal structure, glossiness and iridescence can attract foraging bees.

Plants in a warmer world

As the planet warms, the IPCC has shown that there will be an overall decrease in crop productivity. Climate change has had an overall negative impact on crops in the past 10 years, with extreme droughts and flooding leading to rapid price spikes, especially in wheat. Dr. Kerry Franklin is investigating the interaction between light and temperature responses in plants. High temperatures induce a similar reaction in plants to that of shade; plants elongate, bend their leaves upwards and flower early, which is likely to reduce their overall yield. We need to understand the benefits and costs of plant responses to temperature, and look for alternative growing approaches to maintain and hopefully even increase crop yields in a warmer world.

What does the future hold?

The IPCC report shows that if nothing changes, we are rapidly heading towards a global catastrophe. Food production will drop, which combined with the increasing population means that billions of people could face starvation. The IPCC is keen to highlight that new ways of growing and distributing food may mitigate some of the consequences that we can no longer avoid, and a key part of that is understanding how plants (and their pathogens) will respond to changes in temperature, water availability and increases in CO2.

The research by some of the University of Bristol’s plant scientists, highlighted above, should provide important knowledge that plant breeders can utilise to develop and grow crops more suited to the daunting world that climate change will present.

This blog is written by Sarah Jose, Cabot Institute, Biological Sciences, University of Bristol

You can follow Sarah on Twitter @JoseSci

Sarah Jose

2nd Generation biofuels: a transdisciplinary dialogue

Posted on March 24, 2014April 19, 2023 by janet.crompton

“Globally, there are politically important evidence gaps, but nationally, those evidence gaps are just not important enough for policy-makers to take account of them”.

This was one comment summing up the discussion I had at a workshop on the development of 2nd generation, or cellulosic, biofuels (biofuels produced from crops or waste, that is not otherwise used as food). The workshop’s aim was to produce ‘A transdisciplinary dialogue on the opportunities and challenges of cellulosic ethanol in the UK’, and was run by Dr. Kate Millar, the Director of the Centre for Applied Bioethics. It was part of a number of events convened for the EU Framework 7 project, “Integrated EST-Framework” (EST-Frame). Bringing together 12 scientists, engineers, environmental scientists and social scientists is not an easy feat, but the 24 hours’ of the workshop produced some extremely interesting discussions.

My own research considers endeavours to overcome some of the sustainability problems commonly associated with 1st generation biofuels (e.g. sugarcane and wheat), and so I was particularly interested in how the development of 2nd generation biofuels might change the sustainability landscape. Would many of the problems associated with biofuels in general – increased greenhouse gas (GHG) emissions when compared with fossil fuels, land grabbing, food insecurity and biodiversity loss – disappear if we were to start producing 2nd generation biofuels?

Policy problems

Oilseed rape grown for 1st
generation biofuel has limitations.
Image credit: Richard Webb

Much of the first day of the workshop was spent discussing ‘policy problems’ that would need to be overcome for the successful production of cellulosic biofuel for consumption in the UK. 2nd generation biofuels have not been viably commercialised to date largely because of the cost of production. But this is not the only policy problem to be overcome. 2nd generation biofuel will not only come from ‘waste’, but also from crops, such as miscanthus, which are specifically grown as biofuel feedstock. But policies to encourage the use of crop residues for biofuels, depend, first, upon the categorisation of the cellulose left behind in the farming of particular crops as ‘waste’ and, second, upon a decision that the ‘best’ use of that waste is its conversion to energy. This decision may, in turn, depend upon an assumption relating to national energy security.

When discussing the problems that would need to be overcome for the production of 2nd generation biofuel, it soon became clear that our own understanding of the problems depended upon the frames through which they were envisioned, and/or the assumptions that might be made in even categorising them as problems in the first place. Such frames and assumptions need to be unpicked when making policy decisions relating to, for example, the ‘best’ use of land, the ‘best’ conversion processes, displacement effects resulting from the adoption of those policies, and the valuations made in assessing ‘costs’ resulting from the production of such biofuels.

Indirect land use change (ILUC)

One thorny issue relating to biofuels production has been that of ILUC. ILUC has been a huge spoke in the wheel of policy-makers’ development of policy in relation to the development of biofuels, not only in the UK, but in the EU, and further afield. Endeavouring to tackle this issue involves identifying potential knock-on effects resulting from direct land use change to biofuels feedstocks (whether 1st or 2nd generation). These might include increased GHG emissions, erosion, biodiversity loss, or increased insecurity in relation to land rights or food supply of local people.

While the focus of policy-makers’ concerns in relation to ILUC has to date been GHG emissions, views in relation to all of these issues also depend upon one’s assumptions/framing. Furthermore, such issues are by their very definition uncertain (because they involve future potential scenarios) and, in tackling each of them, require policy-makers to give value (either positive or negative value) to those potential scenarios. Some of the values endowed by policy-makers in assessing indirect or direct land use change may be quantifiable. Others, such as the values given by local people to their landscape before it is transformed for biofuel feedstocks, may not be. Moreover, land use change resulting from policies made in the UK, may be taking place in countries as far afield as Africa or South East Asia, for example.

While some participants thought that this demonstrated that even endeavouring to tackle an issue such as ILUC was purely altruistic, and therefore usually not important enough for national policy-makers to be swayed by, others argued that it was not altruism that demanded its recognition, but an appreciation of the integrated nature of our world, its people and environment, and markets for feedstocks. Without actively sympathising with policy-makers, many participants recognised that there are no right answers when it comes to ILUC.

Need for a holistic approach in policy-making

Image by Steve Jurvetson

When discussion moved on to consider the types of evidence required for policy-makers to tackle the policy problems, we soon realised that different forms of ‘evidence’ were often integrated. Moreover, it was not lack of evidence that was the problem for policy-makers, or even ambiguity and uncertainty in the evidence, but the appraisal of that evidence. This requires political decisions to be taken, something that policy-makers seem, ironically, to be distinctly uncomfortable with in relation to this area.

The workshop was a valuable exercise. To paraphrase one participant: many of the technical or economic issues relating to the development of cellulosic biofuels in the UK could be resolved by taking a very narrow view of the problem. However, such issues do encompass wider issues. Countering the scientists’ and engineers’ ‘problem-solving’ approaches to policy issues, with social scientists’ more critical understanding of the social issues surrounding the problems is always going to be a challenge, but one that, I believe, is crucial if those problems are really going to be solved with any success.

This blog is written by Cabot Institute member Dr Elizabeth Fortin, University of Bristol Law School.