Voodoo wasps that could save the world

Genetic breakthrough could enable scientists to unleash armies of insects on deadly crop pests

(Peter Koomen and Mathijs Zwier (University of Groningen) )

They are so small that most people have never even seen them, yet "voodoo wasps" are about to be recruited big time in the war on agricultural pests as part of the wider effort to boost food production in the 21st century.

The wasps are only 1 or 2 millimetres long fully-grown but they have an ability to paralyse and destroy other insects, including many of the most destructive crop pests, by delivering a zombie-inducing venom in their sting.

Now scientists believe they have made the breakthrough that will enable them to recruit vast armies of voodoo wasps to search and destroy farm pests on a scale that could boost crop yields without polluting the wider environment with insecticides.

The researchers have decoded the full genomes of three species of parasitic wasp, which could lead to the development of powerful new ways of deploying these tiny insects against the vast range of pests that destroy billions of tonnes of valuable crops each year.

There are more than 600,000 species of parasitic voodoo wasps and they already play a critical role as a natural regulator of insect populations. However, scientists believe that the decoding of their genomes will open the door to new and better better ways of targeting them against specific pests.

"These genome sequences will be a major tool for agricultural pest control. Many people may not realise how dependent humans are on these tiny wasps which protect our food crops and save billions of dollars each year by reducing crop loss," said Chris Smith of San Francisco State University, a member of the research team.

The three wasps all belong to the Nasonia genus and are strictly speaking "parasitoid" species, meaning that they lay their eggs inside the paralysed bodies of other insects, keeping them alive long enough for the wasp larvae to grow and mature into adults as they feed off the living flesh of their "zombie" host.

"Parasitic wasps attack and kill pest insects, but many people don't even notice them or know of their important role in keeping pest numbers down. We owe them a lot. If it weren't for parasitoids and other natural enemies, we would be knee-deep in pest insects," said Professor John Werren of the University of Rochester, who led the study published in the journal Science.

"If we can harness their full potential, they would be vastly preferable to chemical pesticides which broadly kill or poison many organisms in the environment. We basically broadcast toxins into the environment – pesticides to control in a very non-specific way a large number of pests. As a result the environment is exposed to these toxins, and we are as well."

The scientists hope that deciphering the genomes of the Nasonia wasps will enable them to find the insect genes involved in directing a wasp to attack a specific insect, with the aim of understanding how to manipulate such attacks. The researchers also hope to identify the chemical nature of the venoms used by the wasps to paralyse their hosts, a development that could also lead to new drugs for human medicine.

Parasitoid wasps are already used as natural pesticides. Last year, for instance, scientists in the US released thousands of parasitic wasps to attack the olive fruit fly, which is decimating the olive groves of California. The wasp is harmless to people, pets and plants.

Scientists also believe that knowing the genomes of the Nasonia wasps will help in the fight against human diseases that are carried by insects. It may be easier to control the disease-carrying insect using the parasitic wasps, rather than targeting the disease itself.

Insects: Back from extinction

They do sea eagles. They do red kites. They do corncrakes. And now, they're doing bumblebees.

The Royal Society for the Protection of Birds, not content with successfully reintroducing some of Britain's most charismatic and endangered bird species, is turning its attention to insects. With the help of conservation partners, it is bringing back endangered species of bees, crickets, hoverflies and moths on its vast national network of nature reserves.

It is the RSPB's contribution to 2010 as a special wildlife year - this is the International Year of Biodiversity - and opens up the possibility of much wider restoration of lost wildlife species in Britain than has hitherto been considered practicable.

The list of insects to be brought back is headed by the short-tailed bumblebee, now extinct - it was once widespread in the south of England but disappeared as a result of changes in farming methods, with the last recorded UK population being in 1988.

However, populations taken to New Zealand by British settlers a century ago have survived and some will be brought back for release this summer on the RSPB's Dungeness reserve in Kent, with the help of the Bumblebee Conservation Trust, Natural England, and Hymettus, a bees and wasps conservation group.

Another project, also in cooperation with Natural England, will be the reintroduction of field crickets to the RSPB reserves at Farnham Heath, Surrey and Pulborough Brooks, West Sussex in April. Field cricket populations have declined severely due to loss of habitats such as lowland heathland and grassland, and were at their lowest point in the late 1980s after they were reduced to a single surviving colony of just 100 individuals in Sussex.

In Scotland, the RSPB and Scottish Natural Heritage will be laying the groundwork for a planned reintroduction of the threatened pine hoverfly to the RSPB's Abernethy reserve in 2011. One of Britain's most endangered insects, the pine hoverfly only breeds in the hollows of tree stumps created by fungi, and changes in forestry practices have led to a crash in its population.

Also in Scotland, the RSPB and Butterfly Conservation this year will establish a captive breeding programme in an attempt to create a sustainable population of the rare dark bordered beauty moth, which lives in aspen woodland and heathland, currently only in two colonies in Scotland and one in northern England. If this is successful the moths will be released at a Scottish RSPB reserve next year.

"The B in our name stands for birds - and we stand up for birds wherever we can - but our work covers all kinds of wildlife," said Dr Mark Avery, the RSPB's Director of Conservation. "No conservation organisation worth its salt concentrates on just one species and ignores all others. 2010 is the International Year of Biodiversity and that chimes perfectly with our efforts to protect whole ecosystems on our reserves from the smallest bug to the tallest tree.

"We have recorded more than 13,000 different species on our 200 reserves, and only three per cent of those are birds. I'm very excited that they will soon become home to some of the country's most endangered insects."

There was also a longer-term reason for the reintroductions, Dr Avery said – climate change, which would see many creatures seeking to move northwards. Some species, especially birds, would be able to do this easily, but others would not. "Over the next few decades we may have to move species to where they need to be, rather than where they are," he said.

Michael McCarthy