Plague of army­worms on the march

South­ern African crops dec­i­mated

The Star Late Edition - - WORLD - WASH­ING­TON POST

SOUTH­ERN Africa has been struck by a pesti­lence so se­vere that farm­ers have in­voked plagues of bi­b­li­cal pro­por­tions. Hun­gry cater­pil­lars called fall army­worms are on the move across the con­ti­nent from Zam­bia south­ward.

Early this month, South Africa’s Agri­cul­tural Depart­ment is­sued a re­port not­ing that, for the first time, this un­fa­mil­iar pest had been spot­ted in the Lim­popo prov­ince.

“Lit­tle is known on how this par­tic­u­lar pest en­tered south­ern Africa,” said the re­port.

“Since this pest is very new in Africa, very lit­tle is known on its long-term ef­fects.” It was pos­i­tively iden­ti­fied as the fall army­worm a few days later.

“It has come in like one of the 10 plagues of the Bible,” Ben Freeth, who op­er­ates a com­mer­cial farm in Zim­babwe, said.

“It is wide­spread and seems to be spread­ing rapidly. It can lay up to 2 000 eggs and its life cy­cle is very quick.”

Army­worms – which grow into moths and are not, tech­ni­cally speak­ing, worms – are so named for their abil­ity to de­stroy mas­sive amounts of crops, in the man­ner of troops tram­pling over a coun­try­side.

Ken­neth Wil­son, who is study­ing the use of bi­o­log­i­cal par­a­sites to bat­tle crop pests at Eng­land’s Lan­caster Uni­ver­sity, de­scribed the havoc as the com­bi­na­tion of two species: a surge in the pop­u­la­tion of the na­tive African army­worm, plus the fall army­worm, an in­vader from the Amer­i­cas.

African army­worms eat in hordes as dense as 1 000 cater­pil­lars per square me­tre, Wil­son noted, strip­ping maize plants bare.

The new­com­ers may be no less de­struc­tive.

“The im­pact of the fall army­worm is likely to be dev­as­tat­ing be­cause it eats the leaves of the plant as well as its re­pro­duc­tive parts,” Wil­son wrote.

“This dam­ages or de­stroys the maize cob it­self.”

He cited an es­ti­mate that put Zam­bia’s pos­si­ble losses of maize, an im­por­tant grain sta­ple, as high as 40%.

“The sit­u­a­tion re­mains fluid. Pre­lim­i­nary re­ports in­di­cate the pos­si­ble pres­ence (of the pest) in Malawi, Mozam­bique, Namibia, South Africa, Zam­bia and Zim­babwe.

Zim­babwe has pos­i­tively iden­ti­fied the pres­ence of the pest while the rest are ex­pected to re­lease test re­sults soon,” said David Phiri, the UN Food and Agri­cul­ture Or­gan­i­sa­tion’s south­ern Africa re­gional co-or­di­na­tor.

The Food and Agri­cul­ture Or­gan­i­sa­tion has set up an emer­gency meet­ing to dis­cuss plans to com­bat the pests.

The Zam­bian gov­ern­ment ac­quired in­sec­ti­cides and has be­gun stock­pil­ing seeds to help farm­ers re­plen­ish con­sumed crops.

Mean­while, South Africa plans to im­port pheromone traps to catch and iden­tify the ex­tent of the pests’ spread.

Pes­ti­cides have shown to be ef­fec­tive against army­worms in the past, Wil­son noted.

But it is not yet known if the cur­rent cater­pil­lar out­break has de­vel­oped a re­sis­tance to the usual chem­i­cals that kill them.

What’s more, as moths, army­worms are known to fly great dis­tances

In 2012, US Agri­cul­ture Depart­ment en­to­mol­o­gists tracked fall army­worm pop­u­la­tions trav­el­ling from south­ern Texas to Min­nesota.

“Only time will tell,” Wil­son wrote, “what the full im­pact of this army­worm in­va­sion will be.”


A crop-eat­ing army­worm on a sorghum plant.

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