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Zambia’s Armyworm Outbreak: Is Climate Change to Blame?

Zambian farmer Surrender Hamufuba inspecting a maize plant in his field. Experts say a changing climate is bringing more crop pests to parts of Africa. Credit: Friday Phiri/IPS

Zambian farmer Surrender Hamufuba inspecting a maize plant in his field. Experts say a changing climate is bringing more crop pests to parts of Africa. Credit: Friday Phiri/IPS

PEMBA, Zambia, Jan 23 2017 (IPS) - Surrender Hamufuba of Mwanamambo village in Pemba district recalls how he battled Armyworms in 2012. Fast-forward to 2016 and it is a similar story — another pest infestation on an even larger scale.

“I am not sure why, but there could be more to the increased frequency of these pest attacks, maybe weather changes,” speculates the 48-year-old farmer, who seems quite knowledgeable about climate smart agricultural fundamentals.

“As temperature is projected to rise, insects like stalk borers will develop faster and this could lead to earlier population growth than expected.” --Researcher Donald Zulu

Out of the five hectares he planted, Hamufuba estimates the damage to be up to 1ha. In Pemba alone, at least 5,000 smallholders have reported some stalk borer damage in varying proportions.

Aside from the stalk borers, the Armyworm invasion has caused larger damage across the country. According to Minister of Agriculture Dora Siliya, at least 124,000 hectares of maize have been invaded, representing just under 10 percent of the 1.4 hectares of maize planted this farming season.

National Coordinator of the Disaster Management and Mitigation Unit (DMMU) Patrick Kangwa said “the pests were under control” as government bought and delivered 87,000 litres of pesticides for spraying in the affected farmers’ fields.

While farmers are being supported in every way possible to safeguard their crops in the short term, the long-term concern is the frequency — and unpredictability — of these devastating pests.

Donald Zulu, a lecturer and researcher at the Copperbelt University, says climate change may complicate the pattern of infestations.

“Outbreaks of Armyworms are highly dependent on the seasonal patterns of wind and rainfall. With global warming, the weather pattern in Africa will continue to change, which could mean more or fewer Armyworm outbreaks,” says Zulu, prescribing long-term integrated approaches built around “robust, country-wide surveillance and early warning systems” considering the devastating nature and feeding pattern of Armyworms.

Armyworms are serious migratory crop pests that feed on young maize plants, and also attack other cereal crops such as wheat, rice, sorghum, millet and most grass pastures, affecting both crop and livestock production. They feed with such devastating speed that by the time they are discovered, notable damage would already have been caused. Stalk borers on the other hand, have the habit of boring into stalks, affecting plant growth.

There are several types of Armyworms, among them the African Armyworm, which occur in Africa. While the 2012 attack was the African Armyworm, this year’s outbreak is different.

“This particular pest is the Fall Armyworm, and not the African Armyworm,” says Dr. Eliot Zitsanza, chief scientist at the International Red Locust Control Organisation for Central and Southern Africa (IRCO-CSA). “The two are closely related though. The Fall Armyworm is native to the Americas and may have been introduced to Zambia accidentally.”

Coincidentally this year, the Armyworm outbreak is occurring alongside stalk borers. Both belong to the same scientific family, called ‘Noctuidae’, of moths. From a scientific perspective, the two types of pests depend on weather for their production and growth, highlighting another importance of reliable early warning systems.

One of the most notable early warning systems uses an extensive network of pheromone traps that attract male armyworm moths using the artificial scent of mating female armyworms. The catches of Armyworm in the traps are used in combination with local weather reports to forecast armyworm outbreaks and help to alert farmers much faster to the need for control.

But with global warming causing massive weather unpredictability, is it to blame for increased incidences of pests? Professor Ken Wilson of Lancaster University, who has been studying Armyworms for 25 years, says it is very likely that over a few decades, the pattern of outbreaks has changed.

“It is very likely that climate change will affect the incidence of this pest because the armyworm is dependent on weather, so it feeds on crops and grasses that are dependent on the amount of rainfall, and the pattern of outbreaks depends very much on where rain storms occur and how frequently they occur,” Prof. Wilson told IPS, pointing out however, that the relationship is not simple as “we don’t have very good data and information to validate this hypothesis.”

As for stalk borers, just like most insects, they are directly under the control of temperature for their growth and it is the most important environmental factor influencing insect behavior, says Donald Zulu. “As temperature is projected to rise, insects like stalk borers will develop faster and this could lead to earlier population growth than expected.”

The Inter-Governmental Panel on Climate Change’s (IPCC) fifth assessment report confirms this strong linkage between warming and increased pest and disease. In highlighting the major risk posed by climate change to agriculture — reduction in crop productivity associated with heat and drought stress — the report cites increased pest and disease damage and flood impacts on food system infrastructure as key indicators.

Similarly, in identifying key adaptation issues and prospects, the report highlights adoption of stress-tolerant crop varieties, irrigation, and enhanced weather observation systems.

While several arguments may have emerged since the outbreak, Southern Province Agricultural Coordinator Max Choombe points to mono-cropping as a major reason, especially for the stalk borer outbreak.

“I believe mono-cropping has brought about this burden because our farmers grow maize after maize, they don’t change,” laments Dr. Choombe, insisting on the importance of crop rotation for breaking the cycle of pests.

Dr. Choombe also believes climate change is a precursor to pest infestations and does not rule out the linkage between the current outbreak and global warming. “Climate change also is a problem, is a precursor for certain pests attack and I believe the attack this season could be as a result of the extreme weather changes we have been experiencing.”

With a looming outbreak of Red Locusts as forecast by the IRCO-CSA, there could be more work ahead in identifying long-term solutions to the rising challenge of pests in a changing climate. Further, the entry into force of the Paris Agreement on Climate Change, which places obligations on individual countries to contribute to a global transition to green growth, means that Zambian policy makers would have to double their efforts considering that agriculture is at the forefront of the country’s vulnerability to climate change.

But while they do, Donald Zulu strongly believes in the following premise: “It is generally agreed that the earth is warming. And temperature influences insect development and is the most important environmental factor that affects insect pests. Because of this, climate change is more likely to influence insects’ geography distribution and affect crops.”

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