B is for biotype, and very bad bug

A nasty sort of whitefly seems bent on world domination, says David Spark

The new strain of a virus-transmitting whitefly that wreaked havoc among California's vegetables in 1991 is spreading further and further round the world. It is rife among tomatoes in Spain. It has reached Australia and threatens Asia, Africa and South America.

The B biotype, as it has been termed, of the tropical whitefly Bemisia tabaci resists insecticides, multiplies five times as fast as other biotypes, transmits up to 60 viruses and can colonise about 600 different crops and weed species.

The British team that studies whiteflies on a world scale is, however, starved of funds to combat the pest. "We are ideally sited to work on tropical problems such as this," says Dr Peter Markham at the John Innes Centre, in Norwich. "We are far enough north to work safely. But we can't get funding."

One reason is that the B biotype is not a British problem, though it presents a potential threat to cabbages, potatoes, tomatoes and French beans grown in other parts of Europe. The Ministry of Agriculture requires that plants brought into Britain be certified free of it.

Peter Markham is applying through the International Cotton Advisory Committee to the Common Fund for Commodities for money to design a cotton resistant to leaf curl virus or its transmission. This is carried by a different, but also aggressive, form of Bemisia tabaci in Pakistan. It has just devastated a million hectares of cotton there.

Here Dr Markham runs into another problem. An American firm, Agracetus, interested in producing better and also coloured cotton, has taken out a patent covering any cotton changed by genetic engineering. The US Patent Office wants to revoke this wide patent but it remains in force in the United States and India. Patent applications are pending in two other big producers, Brazil and China. Agricetus makes money by licensing, but licences can be costly and restrictive.

Whiteflies are tiny, moth-like creatures whose scale-like young feed on plants. Dr Markham and his colleague Ian Bedford have shown that, until the Eighties, each part of the tropical and sub-tropical world had its own type of Bemisia tabaci. This fed on a limited range of plants. Then the less choosy B biotype appeared in the Caribbean, followed by Central America, Florida and California. In the initial attack, California and other southern US states suffered $500m (£316m) losses of vegetables. The flies have also invaded the glasshouses of the Netherlands.

Travelling in their millions, sometimes like a cloud of smoke, they attack a wide range of vegetables and crops, spreading virus diseases that curl the plants' leaves and stunt their growth. Viruses used to present no problem to vegetables of the cabbage family. They do now.

The saliva of the B biotype poisons some plants. Marrow and squash leaves turn silver. As well as suffering from leaf curl, tomatoes ripen unevenly and become pithy and unfit for sale. The Dominican Republic lost nearly 20,000 hectares in a season.

Honduras has suffered heavy losses of cotton, tomatoes and beans, important for the local poor. California, despite its resources for pest control, is still losing $130m of crops, including 4 million acres of melons, per year.

The B biotype's wide range of food plants means that, when one crop dies, it need not die along with it; it can move to another or to a weed.

One question is what will happen when it reaches parts of Africa and Asia populated by other biotypes. In California, the local biotype has now disappeared.

Silverleaf, a characteristic of the B biotype, was spotted in Israel in 1967, and so the B seems to come from the Middle East. Scientists believe that heavy use of pesticides gave an advantage to a biotype which was pesticide-resistant and could multiply fast.

The trade in ornamental plants attractive to the B biotype then provided a means of spreading it to the Americas, Europe, Japan and Australia. A tiny scale can be hard to detect on a plant leaf.

Elsewhere, again under pesticide pressure, local whiteflies have become pesticide-resistant and more fecund. Cassava, a staple food throughout Africa, has been badly damaged in Uganda by mosaic virus, as a result of a new surge of whitefly activity.

In Pakistan, whitefly used to be a late-season pest making cotton sticky with honeydew. By the mid-Eighties, however, it was present throughout the year, including the hot early season: and whitefly transmits virus more efficiently in the heat.

The first important outbreak of leaf curl virus took place at Multan in 1988, when Pakistan introduced a cotton variety susceptible to it. Since then, the virus has spread through the Punjab where small farmers produce most of the cotton on which two-thirds of Pakistan's exports depend.

Peter Markham says: "The misuse of insecticides over 40 years has encouraged supertypes of whitefly which are now uncontrollable."

In Britain, the glasshouse whitefly, which is a different species, is controlled by a parasitic wasp whose larvae grow in whitefly scales and hatch more wasps to attack more scales. Unfortunately, these wasp larvae do not always mature in scales of the tropical whitefly. So there are too few new-generation wasps.

The hunt goes on worldwide for possible predators of the B biotype. If scientists could be sure where it evolved, they might be more successful in this search. The problem remains, however, that only a few whitefly remaining alive can spread viruses through a whole field. This is why Dr Markham wants to develop virus-resistant cotton.

He sees it as part of an integrated pest management strategy, using as little chemical as possible and encouraging natural enemies of cotton pests. It would enable farmers to target whichever pest got out of control without having to worry about eliminating whitefly completely, an almost impossible task. Whitefly is only one of five major pests of cotton.

Although integrated pest management is a fashionable idea, many experts, Dr Markham believes, lack the will to use the whole armoury of control measures. They are wedded to one approach or another.

Rice pests have been controlled in Indonesia by stopping the use of insecticides and encouraging insect-eating spiders. But what works in one place will not necessarily work elsewhere. "A lot more research is needed," says Dr Markham.

Tommy Ramone performing at The Old Waldorf Nightclub in 1978 in San Francisco, California.
peopleDrummer was final surviving member of seminal punk band
Life and Style
Swimsuit, £245, by Agent Provocateur

Diving in at the deep end is no excuse for shirking the style stakes

The Mexico chief finally lets rip as his emotions get the better of him
world cup 2014
German supporters (left) and Argentina fans
Final gives England fans a choice between to old enemies
Spectators photograph the Tour de France riders as they make their way through the Yorkshire countryside
voicesHoward Jacobson: Line the streets for a cycling race? You might just as well watch a swarm of wasps
Life and Style
lifeHere's one answer to an inquisitive Reddit user's question
peopleDave Legeno, the actor who played werewolf Fenrir Greyback in the Harry Potter films, has died
Mario Balotelli, Divock Origi, Loic Remy, Wilfried Bony and Karim Benzema
transfersBony, Benzema and the other transfer targets
Yaya Touré has defended his posturing over his future at Manchester City
Detail of the dress made entirely of loom bands
ebookA unique anthology of reporting and analysis of a crucial period of history
Life and Style
There were mass celebrations across Argentina as the country's national team reached their first World Cup final for 24 years
transfersOne of the men to suffer cardiac arrest was 16 years old
Arts and Entertainment
Armando Iannucci, the creator of 'The Thick of It' says he has
tvArmando Iannucci to concentrate on US show Veep
A mugshot of Ian Watkins released by South Wales Police following his guilty pleas
peopleBandmates open up about abuse
Basketball superstar LeBron James gets into his stride for the Cleveland Cavaliers
sportNBA superstar announces decision to return to Cleveland Cavaliers
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

C# Developer (HTML5, JavaScript, ASP.NET, Mathematics, Entity)

£30000 - £45000 per annum + Benefits + Bonus: Harrington Starr: C# Developer (...

C# Integration Developer (.NET, Tibco EMS, SQL 2008/2012, XML)

£60000 - £80000 per annum + Benefits + Bonus: Harrington Starr: C# Integration...

Biztalk - outstanding opportunity

£75000 - £85000 per annum + ex bens: Deerfoot IT Resources Limited: Biztalk Te...

Trade Desk Specialist (FIX, Linux, Windows, Network Security)

£60000 per annum: Harrington Starr: Trade Desk Specialist (FIX, Linux, Windows...

Day In a Page

A History of the First World War in 100 Moments: Peace without magnanimity - the summit in a railway siding that ended the fighting

A History of the First World War in 100 Moments

Peace without magnanimity - the summit in a railway siding that ended the fighting
Scottish independence: How the Commonwealth Games could swing the vote

Scottish independence: How the Commonwealth Games could swing the vote

In the final part of our series, Chris Green arrives in Glasgow - a host city struggling to keep the politics out of its celebration of sport
Out in the cold: A writer spends a night on the streets and hears the stories of the homeless

A writer spends a night on the streets

Rough sleepers - the homeless, the destitute and the drunk - exist in every city. Will Nicoll meets those whose luck has run out
Striking new stations, high-speed links and (whisper it) better services - the UK's railways are entering a new golden age

UK's railways are entering a new golden age

New stations are opening across the country and our railways appear to be entering an era not seen in Britain since the early 1950s
Conchita Wurst becomes a 'bride' on the Paris catwalk - and proves there is life after Eurovision

Conchita becomes a 'bride' on Paris catwalk

Alexander Fury salutes the Eurovision Song Contest winner's latest triumph
Pétanque World Championship in Marseilles hit by

Pétanque 'world cup' hit by death threats

This year's most acrimonious sporting event took place in France, not Brazil. How did pétanque get so passionate?
Whelks are healthy, versatile and sustainable - so why did we stop eating them in the UK?

Why did we stop eating whelks?

Whelks were the Victorian equivalent of the donor kebab and our stocks are abundant. So why do we now export them all to the Far East?
10 best women's sunglasses

In the shade: 10 best women's sunglasses

From luxury bespoke eyewear to fun festival sunnies, we round up the shades to be seen in this summer
Germany vs Argentina World Cup 2014: Lionel Messi? Javier Mascherano is key for Argentina...

World Cup final: Messi? Mascherano is key for Argentina...

No 10 is always centre of attention but Barça team-mate is just as crucial to finalists’ hopes
Siobhan-Marie O’Connor: Swimmer knows she needs Glasgow joy on road to Rio

Siobhan-Marie O’Connor: Swimmer needs Glasgow joy on road to Rio

18-year-old says this month’s Commonwealth Games are a key staging post in her career before time slips away
The true Gaza back-story that the Israelis aren’t telling this week

The true Gaza back-story that the Israelis aren’t telling this week

A future Palestine state will have no borders and be an enclave within Israel, surrounded on all sides by Israeli-held territory, says Robert Fisk
A History of the First World War in 100 Moments: The German people demand an end to the fighting

A History of the First World War in 100 Moments

The German people demand an end to the fighting
New play by Oscar Wilde's grandson reveals what the Irish wit said at his trials

New play reveals what Oscar Wilde said at trials

For a century, what Wilde actually said at his trials was a mystery. But the recent discovery of shorthand notes changed that. Now his grandson Merlin Holland has turned them into a play
Can scientists save the world's sea life from

Can scientists save our sea life?

By the end of the century, the only living things left in our oceans could be plankton and jellyfish. Alex Renton meets the scientists who are trying to turn the tide
Richard III, Trafalgar Studios, review: Martin Freeman gives highly intelligent performance

Richard III review

Martin Freeman’s psychotic monarch is big on mockery but wanting in malice