Liberian crop pest mystery solved

James Morgan, BBC News 3 Feb 09

A mystery pest which has devoured crops and contaminated water in Liberia and Guinea has finally been identified.

The insects, thought to be armyworms, are in fact the caterpillars of the moth Achaea catocaloides, says the UN's Food and Agriculture Organization.

Cornering the culprit will allow the government to select the best pesticide to tackle the outbreak - the worst seen in Liberia since 1970. More than 20,000 people have so far had to evacuate their homes.

As well as devouring coffee, cocoa and plantain crops, the invaders have polluted drinking water sources with their faeces.

Emergency measures

Liberian President Ellen Johnson-Sirleaf declared a national state of emergency after caterpillars were reported to have infested more than 100 villages, including several over the border in Guinea.

During a field investigation last week, insect scientists from the FAO and the Liberian Agriculture Ministry took samples of the caterpillars, their larvae and their pupae.

They established that the insects were not armyworms, as had been reported, but could not identify the species.

The team sent pictures of both moths and caterpillars to experts at the International Institute of Tropical Agriculture in Nigeria.

They confirmed that the species is A.catocaloides, a pest endemic to West Africa.

"The farmers in Liberia know these caterpillars but they have never seen them on this scale. It is extraordinary what has been seen here," said Dr Winfred Hammond, an FAO entomologist, based in Accra, Ghana.

Farmers were described as "shocked" by the scale of the swarms, in a report by the investigations team.

"The citizenry were horribly alarmed and frightened as they saw their environment (crops, water and buildings) covered by swarms of caterpillars and therefore had to cry for help," said the report.

"The government responded positively... but the country was ill-prepared for containment since it lacked the capacity for actual diagnosis of the situation and institutional structures and resources for efficient and effective containment."

One piece of good news for farmers is that the caterpillars are likely to be easier to control than armyworms would have been.

They spin their cocoons on the ground under fallen leaves, which leaves them relatively exposed. Armyworms bore 4-5cm into the ground to pupate and are thus much tougher to eradicate.

The next stage is to step up a program of pesticide spraying which until now has failed to reach any more than a dozen of more than 100 affected villages, according to Dr Hammond.

"We really have some homework to do now - because the caterpillars are still spreading. They are in Guinea already," he told BBC News.

Learning lessons

"We cannot avoid applying pesticides. Now that we have an accurate identification, we can choose a pesticide which is specific to this species of caterpillar.

"But in the long term, we have to take this as an opportunity to develop early warning strategies for countries in West Africa. Not only for these caterpillars, but for other migratory pests."

Dr Hammond spoke on his way to an emergency meeting in Liberia, where representatives from the governments of Liberia and Guinea, the regional grouping Ecowas, and the FAO will discuss strategies for halting the spread of the caterpillars.

One challenge will be reaching the sites of the caterpillar eggs - which are laid on the leaves of very tall Dahoma trees.

These eggs hatch into caterpillars which feed on the leaves of the trees until they mature and fall to the ground, where they pupate.

Caterpillars which are not yet mature begin migrating in search of food - leading them to crop fields, into water bodies and residential areas.

The cause of this year's unexpectedly large outbreak is likely to be unusual weather patterns, according to Dr Kenneth Wilson, an ecologist from Lancaster University.

"With such widespread outbreaks, something has to be done," said Dr Wilson, an expert on armyworms.

"Because the larvae pupate above ground, destroying these by trampling or fire is an option, but if the outbreaks are really extensive then this might have little impact at national level.

"Vigilance is the key, as control will be much easier if that they stamp down on the next generation of outbreaks early on, when the caterpillars are small and vulnerable.

"However, if they are feeding in tall trees, this can be extremely difficult without aircraft sprayers."

Crop-eating caterpillars 'worse' than army worms: Liberia
Zoom Dosso Zoom Dosso, Yahoo News 3 Feb 09;

MONROVIA (AFP) – Caterpillars laying waste to Liberian crops are not army worms as previously believed but a species which may turn out to be even more destructive, the country's agriculture minister warned Tuesday.

"Results indicate that the caterpillars that we are dealing with are not army worms," the minister, Christopher Toe, told journalists.

The caterpillars, which have ravaged central Liberian farms in recent weeks, have been identified as the species Achaea Catocaloides by international research institutions and renowned entomologists, the minister added.

Experts warned that the insects could even turn out to be more destructive that army worms as they attack more crops including coffee and cocoa.

"The destruction of caterpillars we are now confronted with, in my opinion, may be more severe than the army worms because it is attacking a wider range of species (of plants and trees)," said Joseph Subah, the head of the Center for Agricultural Research in Liberia.

The caterpillars have already begun devouring crops in neighbouring Guinea. Liberia's other neighbours Sierra Leone and Ivory Coast are concerned that the invasion could come their way.

Ivory Coast has extra reason to worry as experts warn that the Achaea Catocaloides also destroys cocoa and coffee plantations, crops that army worms do not attack.

Ivory Coast is the world's top cocoa producer and many of its plantations are in the west of the country in a region that borders Liberia.

Alan Schroeder, an entomologist from USAID, told journalist that he had seen this species in action before in Benin.

"If it is the now the same species as in Benin they (Ivory Coast) will suffer more because this species attacks cocoa plantations," Schroeder said.

Abidjan on Tuesday said it had sent a team of experts to Liberia to study the invasion.

In Liberia, Subah told journalists that, in all the affected areas, the caterpillars have gone into the pupa stage, from which they emerge as adult moths. No new case of infestation was reported since Monday, he added.

"We have a total of 107 towns and villages affected in four counties and there are huge amounts of moths in a new area in the northern county of Nimba," he said.

Experts warn the moths could produce a second wave of crop-destroying caterpillars as they start reproducing. It is not known how many eggs the moths can lay but they added that the caterpillar stage lasts about 23 days.

"That is a very long period to cause a lot of damage because it is the larvae (caterpillars) that destroys the crops," insect expert Ibrahim Shamie of Sierra Leone said.

Liberia has declared a state of emergency and called on the international community to help it deal with the plague, but authorities said Wednesday that they had not received substantial financial help so far.

The agriculture minister said Tuesday that he would meet his counterparts from the Mano River Union -- Liberia, Guinea, Sierra Leone and Ivory Coast -- in Monrovia on Friday to discuss the insect invasion.