The Eighth Plague
West Africa's Locust Invasion

Locust plagues are as old as agriculture itself. The first known cases of fields and pastures being devastated by billions of pink and yellow locusts - capable of covering 200 kilometres (km) and eating their own weight in food each day - dates back to the days of ancient Egypt.

Today, there exists - in theory - various methods used to combat locust invasions. Traditionally, farmers have tried to ward off swarms with smoke or noise and their own physical presence in the fields. These methods have been ineffective and make little impact on gigantic swarms as they descend onto farmers' fields to eat.

A number of research institutions have even been studying the option of "biological warfare" - promoting the use of particular birds and specialised parasites hostile to locusts in an effort to reduce their populations. A mushroom that acts as a deadly parasite to locusts, when consumed, has also been developed as part of this approach.

But in recent years, chemical deterrents have mostly been used to poison the insects. The swarms that ravaged parts of West Africa in the summer of 2004 were the biggest in living memory, often stretching over millions of hectares (ha). The cheapest and most effective way to deal with the pests is by spraying them with pesticides. But the use of chemicals has negative side effects. The highly toxic chemicals affect not only locusts, but also humans, animals and the environment. Apart from these dangers, spraying also requires huge logistical resources, which many of the poor countries most affected by locusts cannot afford.

Daily surveillance

Whenever they appear in their huge numbers across West Africa, surveillance teams are the first line of defence in the war against locusts. In Senegal, national soldiers rising at the crack of dawn with agricultural experts - mobilized by the Ministry of Agriculture -inspected fields selected on the basis of data from previous swarms, as well as on the basis of information given by villagers. The geographical coordinates of the swarms, collected using portable global-positioning system units, were carefully recorded.

If helicopters are used, large swathes of land can be monitored in a short time. However, Senegal - where resources limit surveillance - is assisted by a network of village chiefs who alert authorities by phone whenever they spot swarms near or in their villages.

"Surveillance is very much like military reconnaissance," Col Abdourahame Cisse, head of Senegal's Northern Military Zone, told IRIN. "We spot the enemy's [locusts] position, then pass it on to the eradication teams, who then spray the swarm on the ground."

Experts, on board four-wheel drive vehicles equipped with pesticide pumps and sprays, can cover up to 500 ha every day. These plant-protection units represent Senegal's first line of emergency response, but their work was curtailed this year by the short window of opportunity available due to the reproductive cycle and swarming behaviour of the pests.

A carefully timed struggle

When the locust reaches the swarming stage - the most destructive growth phase - it remains on the ground throughout the night. Warmed by the sunrays in the early hours of the morning, it then takes off to look for food. Spraying locusts with pesticides is therefore only possible early in the morning and around sunset. Results are yielded only when they are grounded. Spraying is ineffective if they fly through the chemicals, which then do not have enough time to kill the fast-moving insects.

The locust larvae remains flightless for some time after birth and being less mobile than the adults, it is at this stage that they are easier to eradicate. The length of the spraying season is also limited. Spraying cannot be done effectively during the heat of the day, since the chemicals are liable to evaporate and pose a danger to the applicators. Therefore, it has to be done between 11 a.m. and 4 p.m., even when the locusts are not mobile.

The largest areas are fumigated by light aircraft, but their use also depends on weather conditions and the size of the infested areas.

Hachem Bensid is the pilot of one of two Piper PA 25 aircraft that Morocco loaned to Senegal.

"I was recalled from my vacation on specific instructions from His Majesty [King Mohamed VI of Morocco]," he said. From 8 to 30 September, Bensid conducted 15 spraying missions in less than one a day, in and around the border town of Podor - an area on the northern fringe of the Sahel.

"We cannot fly when the [weather] forecast predicts a sand storm, which are frequent in Podor," Bensid said.

Still, the weather is not the only obstacle. Wide-scale fumigation can be done only on large, open plots of land. Such areas are rare in that part of Senegal, where most people live off what they can grow in the family plot. Fields are interspersed with houses, water points and grazing areas for animals. They cannot be sprayed without running the risk of poisoning animals, as well as the local population.

A cursed solution

The present generation of pesticides is less toxic than its predecessors. Older-generation - organochloric - pesticides had the advantage of remaining active for weeks on the land surface. They continued affecting locusts long after an area was sprayed, while also acting as geographical barriers that poisoned the swarms, which settled on them.

The toxic nature of the active agent used in the old pesticides, chlorine, did not only affect locusts, but also water, pastures and the plant foods consumed by humans and animals risked being contaminated. Today, they are strictly prohibited in many industrialized countries because they are non-biodegradable. In addition to this, insects have developed a certain resistance to these products.

The newer, organo-phosphoric products remain active for less time - only two or three days - and are less dangerous to humans and animals. However, because the effect lasts only a short while, the same plot has to be sprayed every time the swarms return.

The currently used product kills all insects - not only locusts - by inducing fatal neurological malfunctions. The small insects go into convulsions and spit blood for about 30 minutes, after which they die.

Toxicity poses storage problem

The high toxicity of these products has a dramatic consequence for the fight against locusts. Since stocking the pesticides is dangerous for the environment, especially after their expiry date, they are usually manufactured in limited quantities and only to order. In 2004, producers were therefore quickly swamped by the speed at which the current demand increased. Stocks ran out and the region most affected, faced shortages of chemicals, which seriously countered their eradication efforts.

Malathion is one of the new generations of products widely used against locusts. Its pungent smell makes it easy to identify, even at 50 metres (mt) from its metallic-blue containers. Anyone who handles Malathion must be protected by a pure, cotton outfit with gloves, a gas mask and industrial goggles since the product is strongly corrosive and poisonous when touched or inhaled.

For this reason, Malathion has to be sprayed at least 600 mt away from any human settlement. However, this safety measure is rarely respected since the locusts are everywhere and the affected populations are rarely aware of the danger of exposure to pesticides. (See: And then came the locusts)

A drop in the ocean

Army Sgt Serge Sambou participated in "the war on locusts", declared by Senegalese President Abdoulaye Wade in early 2004 when he described his intention to establish a "locust army" to tackle the problem. Travelling in a four-wheel drive vehicle carrying drums of pesticides, he followed an Algerian team bound for Poundioum, a village near the northern town of Saint-Louis. The Algerians, an expert team sent in by their government to assist Senegal, were to work with Sgt Sambou in spraying fields there.

The Algerians had already sprayed the village's fields in the morning, but by midday, a yellow carpet of larvae had appeared, covering the peanut plants as far as the eye could see. Only a few roots were left.

"Sometimes we spray the same area three times, " said Sambou. "For example, you'd never think we were here this morning."

Given the sheer number of insects, the battle seemed lost before it even started. While the teams worked hard, the resources available were not enough. In October, there were only 13 vehicles and four planes for the eradication teams working in northern Senegal. This was in dramatic contrast to the 19 airplanes and nine helicopters that accompanied the Paris-Dakar car rally in 2004.

As the locust invasion dragged on, the money needed to fight it increased.

"In April 2004, [US] $9 million would have been enough to solve the crisis," the UN Food and Agricultural Organization's (FAO's) representative in Senegal, Edouard Tapsoba, said. "Six months later, we need $100 million."

However, despite the immensity of the disaster affecting Senegal, as one of ten affected countries in West Africa, the efforts made have not been in vain. The locusts had been confined to northern Senegal, preserving the country's breadbasket, the central region of Louga.

"We saved Gambia [wedged between northern and southern Senegal] and Casamance [southern Senegal] by preventing the locusts from reaching them," an agricultural engineer at the regional Directorate of Rural Development told IRIN.

This relative victory - or temporary respite - was not only due to eradication efforts, but also due to the locusts themselves. In line with their cyclical migration habits, they started flying north towards Algeria and Morocco at the end of October as winter approached.

The uncharted dangers in using pesticides

When pesticides are used on a large scale, it's not just the locusts that are affected.

Abdou Fall, a Senegalese army doctor who had been monitoring some of the soldiers battling the locusts, said while the fumigators had been trained in safety procedures, there was still a risk of accidents caused by inhaling or consuming the products, such as drinking water from a spring near a recently sprayed area. The symptoms of pesticide poisoning were felt immediately, he said. They included headaches, nausea and loss of balance.

According to Fall, the army had not recorded any such case of poisoning up to October 2004, but the army only monitored the eradication teams, not villagers, so the impact of pesticide fumigation in regard to public health had not really been measured or assessed.

Moreover, the empty pesticide barrels were not systematically taken away and destroyed after they were used.

"We have to destroy the barrels to make sure people don't use them as water troughs and poison their animals, or their families," Fall said, but to date they stand empty and abandoned.

The impact of pesticides on the land, water, livestock and people's health is still not calculated, but critics of the use of pesticides suggest that long after the locusts leave, the dangers remain.

[ENDS]