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Open weekend for the public › Biological Chemistry

The following displays are located in the conference centre.

Bed bug

Who's been sleeping in my bed?

Our homes are full of creepy crawlies such as spiders and flies but what about the ones you can't see? What about the bugs that live in your bed? At our stand you can find out about microscopic dust mites that live in your mattress feeding on your dead skin. These mites cause allergies especially in people with asthma. And if that's not scary enough, our beds now have a new invader, the bed bug! These sneaky bugs feed on your blood at night when you are asleep and they are attracted by odours from your body. Bed bugs have been lying low for the last 60 years but now these blood sucking villains are back with a vengeance! At our stand, you can get up close and personal with the mites and bugs. You can also discover how they find their food (you!) and what scientists at Rothamsted Research and the London School of Hygiene and Tropical Medicine are doing to find better ways to control these pests.

Mosquito

Why me?

Why is it that some people get bitten more than others by mosquitoes? Scientists at Rothamsted, along with the University of Aberdeen, have discovered that it's all to do with the way we smell! Certain people who don't get bitten produce natural repellents in their body odour. At our stand, you can find out how we discovered these repellents and, if you're brave enough, you can even take part in our live experiment to see how attractive YOU are to mosquitoes.

The following displays are located in the Centenary Building.

Fish

Fish oils from plants

You might be too young to remember cod liver oil supplements, but you may have heard of omega-3 fatty acids and their healthy properties. You can buy foods and pills that contain these beneficial compounds, but most of these are derived from endangered fish stocks. Come and see how plant scientists are mining the sea for algal genes to tailor-make plants which produce fish-type oils with human health benefits, without harming the environment.

African maize crop

The root of all evil

In Africa, the maize crop is under attack from a parasitic weed called Striga. This weed has devastating effects on crop production and particularly affects subsistence farmers. When maize plants are grown alongside the legume Desmodium uncinatum, the D. uncinatum plants protect the cereal crop from weed infestation. D. uncinatum suppresses Striga infestation by releasing chemicals from its roots which interfere with Striga development. We want to understand how these chemicals work and what enzymes are responsible for making them.

Collecting plant volatiles

What's in a smell?

Interactions between pests (insects and weeds) and host plants, animals or human beings are mediated by chemical signals (semiochemicals). These complex, naturally-occurring signals are produced in vanishingly small amounts, and their isolation and identification are essential for the understanding of these interactions. Come and see our state-of-the-art equipment and mass spectrometers to see how these signals are captured and identified.

The following displays are located in the large marquee.

Grain aphid

How do insects smell?

Insects use a wide range of chemical signals or semiochemicals such as pheromones, plant volatiles or animal odours to detect each other and to locate suitable plant or animal hosts. Aphids use (E)-ß-farnesene as an alarm pheromone to alert others about danger. This semiochemical enters the antennae via pores, is ferried by the odorant binding proteins (OBPs) across the hydrophilic sensillum lymph and interacts with membrane-bound olfactory receptors, triggering olfactory neurons and avoidance behaviours. Our research objectives are to understand aphid chemical communication systems more fully in order to devise strategies and produce chemical tools for their population control.

Fruit fly head - Photo by Dennis Kunkel

How do insects smell the difference?

Plants attacked by insects produce different chemicals, and different amounts of chemicals, from those which are undamaged. By making electrical recordings from insect antennae (the electroantennogram or EAG) and linking these to gas chromatography (GC), we can discover which chemicals are important for the insect's behaviour.

Inscentinel sniffer bee

Inscentinel Ltd: Trace-vapour detectors using honeybees

Inscentinel Ltd. is a spin-out company from Rothamsted Research, specialising in harnessing the olfactory ability of honeybees for trace-vapour detection. Bees are trained to recognise a particular odour by associating it with a food reward (Classical Pavlovian Conditioning). Subsequently, when the bees detect the odour, they extend their proboscis (tongue) in expectation of food. Using live honeybees, Inscentinel is developing a new generation of vapour detectors, with potential applications ranging from explosives and drug detection to medical diagnosis and food spoilage. Honeybees make excellent sensors because they are inexpensive, quick to train (a few minutes per bee) and have extremely low limits of detection (odours can be detected in minute concentrations).

› Click here for more information about Inscentinel

Larva of African cotton leafworm

Priming plants for self defence: preparing for battle

Plants can develop a primed defence state upon perception of specific environmental signals. This defence priming allows plants to respond more efficiently to incoming attack by disease-causing microbes or herbivorous insects. For instance, when plants are attacked by herbivorous insects, they emit odours that can signal neighbouring plants to prime their immune system. This form of natural plant immunisation can provide broad-spectrum protection against a wide spectrum of diseases and pests. Our research aims to identify the environmental signals that can trigger defence priming in plants, as well as the underpinning mechanisms within the plant. At our stand, you can learn more about how plants prime their immune system and even sniff some of the priming-inducing odours used by plants to forewarn their neighbours against upcoming attack.

Lacewing larva attacking aphid

The smell of fear: how to control aphids the natural way

When an aphid (greenfly) is attacked by a predator, she produces a droplet of liquid which releases a chemical odour or pheromone. This is an alarm pheromone called (E)-ß-farnesene. It alerts neighbouring aphids that a predator is near and causes them to stop feeding and quickly run away. Although the aphid that was attacked has been killed, her warning has saved her sisters. If flying aphids detect this pheromone coming from aphid colonies on a plant, it deters them from settling on the plant. Many plants also produce small quantities of (E)-ß-farnesene naturally, but aphids are not fooled by this plant-produced pheromone due to the presence of similar levels of other plant chemicals. By introducing a gene from a peppermint plant into wheat, we have created wheat that releases relatively large amounts of (E)-ß-farnesene. This masks the other plant chemicals and convinces the aphids that the alarm is real. Thus, the wheat has a natural protection against aphid colonisation and will not require treatment with toxic insecticides.