Day -- After Day After Day After Day -- of the Locusts

Richard Tren | 17 Sep 2004
TCS Daily

In my high school biology class I recall the fascination with which I used to dissect locusts. The animal rights lobby might not like allowing kids to cut up dead stuff but it really brings home basic anatomy -- head, thorax, abdomen and how simple creatures function. That said, locusts really are quite horrible looking creatures, and one time the door to their glass cage opened and about 25 flew around the laboratory. One flew straight into the hair of a girl sitting opposite me -- she naturally freaked out.

Africans in the Sahel are also very familiar with locusts, but their great dread is of locusts getting into their crops rather than their hair. The inhabitants of countries including Mauritania, Mali, Senegal, Niger and Chad have their crops destroyed, putting livelihoods and lives at risk. The region is currently suffering its worst locust infestation for 15 years and a contributory factor is that the public health agencies in those countries can no longer use the single best weapon against locusts -- the insecticide Dieldrin.

In May 2001 the Stockholm Convention on persistent organic pollutants (POPs) was signed; it came into force earlier this year when the 50th nation ratified the treaty. Dieldrin is one of the 'dirty dozen' chemicals, which include the far more famous DDT. But unlike DDT, where an exemption for use was fought for and won, Dieldrin has been consigned to the history books. Of course countries could ask to use it and probably would be granted the right for emergencies, but since stockpiling Dieldrin in case of emergencies is not allowed, and locust swarms don't usually come with the 3 months notice that would be required in order for procurement, delivery and use to take place, it is a de facto total ban.

Meanwhile other insecticides are being rushed to the Sahel. United Nations experts say that time is running out in the battle to contain the infestation. For the past six weeks swarms have flown across the Sahelian Savannah. A swarm of a square mile contains about 150m insects, each eating the equivalent of its own weight a day, which is more dietary intake than 3,000 tree-chomping elephants.

Clive Elliot, who heads the locust group at the UN Food and Agriculture Organisation says that the funding made available to combat the crisis ($39m) is about $60m short of what's required. Without more spraying of insecticides there is no chance of even containing the plague, let alone beating it back. So the breeding goes on. New generations are likely to devastate Burkino Faso and western Niger shortly. The Darfur region of Sudan, already suffering so desperately, will soon have to endure a plague of locusts.

Unless massive spraying happens in the next few weeks, matters will deteriorate rapidly in October. Mr. Elliot told the Financial Times last week that 'The chances of being able to break the cycle at this point are not high'. Breaking the locust life cycle means targeting locusts while they're not yet flying. The wingless juvenile 'hoppers' can still damage crops and become adults, but are easy to kill -- that is if you have a persistent and cheap insecticide.

Dieldrin used to be the answer; it was sprayed across the path of the approaching hoppers. Dieldrin's persistence meant that a single spray of a thin barrier strip was enough to wipe out vast swathes of these hoppers for weeks. In addition to barrier spraying, organophosphate insecticides, such as fenitrothion, were sprayed from planes overflying a locust swarm. Of course, this latter aerial approach is far more expensive and requires a more sophisticated public health program and infrastructure -- and this from countries many of whose people live on less than a dollar day.

Dieldrin was often stored and used improperly in general farming, which caused bioaccumulation and problems for some wildlife species. But even when used as directed it led to some small bird reproductive problems (far smaller than locust plagues of course). There are alternatives to Dieldrin -- such as the newer generation of benzophenyl urea insect growth regulators, which are almost as effective against the hoppers as Dieldrin, but are twice as expensive.

There are also fungal pathogens that can attack the locust. One such biopesticide spray consisting of a natural fungus called Metarhizium kills the locusts within three to four weeks. Other products affect the insect growth regulators and disrupt the moulting process, so the locusts never reach adulthood. Without funding the small scale trials of these products will never be expanded, but further research is essential because unknown consequences may follow from introducing such biopathogens into the environment. But this is for the future.

The direct result of not using Dieldrin is that Sahelian Africa is experiencing the worst locust plague in 15 years. Dieldrin, like DDT, should only be used in restricted ways -- primarily controlling swarming locusts. Unfortunately under the POPs Convention ratified this year, it is no longer available to the blighted African nations of the Sahel.

Roger Bate is a visiting fellow of the American Enterprise Institute and a Director of Africa Fighting Malaria.