A farmer shows a crop-eating fall armyworm taken from his field in Gwanda, Zimbabwe. Credit: Busani Bafana/IPS

By Busani Bafana
BULAWAYO, Zimbabwe, Apr 10 2017 (IPS)

Microscopic soil organisms could be an environmentally friendly way to control crop pests and diseases and even protect agriculture against the impacts of climate change, a leading researcher says.

Africa is battling an outbreak of trans-boundary pests and diseases like the invasive South America fall armyworm (FAW), tomato leaf miner and the TR4 which have cost the agriculture sector millions of dollars in crop damage.“Chemicals are a quick fix and short-term solution to insect pest control and also kill the predators of the pests." --Dr. Christian Thierfelder

“Research from our labs at Auburn University has shown a great potential in microbes for helping fight pests- and we have done some research on fall army worm that are pests in turf grass,” said Dr. Esther Ngumbi, a post-doctoral researcher in the Department of Entomology and Plant Pathology at the Auburn University in Alabama, United States.

Ngumbi’s research has looked at how beneficial soil microbes help recruit natural enemies.

Microbes are tiny organisms like bacteria and fungi that interact with the soil and plants. Though not widely appreciated in much of Africa, Ngumbi said microbial formulations have been found to improve plant growth and protect crops from insects, drought and other climate-related extremes.

Researchers also say microbes can help preserve the environment threatened by growing reliance on chemical solutions in fighting crop and livestock trans-boundary pests and diseases. Pesticides pose a threat to food safety, human and ecological health, necessitating the promotion of non-chemical alternatives to handling pests.

Researchers at Auburn University have worked on beneficial soil bacteria/microbes, specifically plant growth-promoting rhizobacteria (PGPR). The soil dwelling bacteria that colonize plant roots have beneficial effects of increasing plant growth and enhancing the ability of plants to fight off herbivorous insect pests such as the beet armyworm-Spodoptera exigua and the fall armyworm Spodoptera frugiperda to which they have a direct toxic effect.

First reported in Sao Tome and Principe in January 2016, the crop-eating pest has affected thousands of hectares of crops in Namibia, Malawi, Mozambique, South Africa, Uganda, Zambia and Zimbabwe to date. The pest which is difficult to control with one type of pesticide can cause extensive crop damage of up to 73 percent in the field. It also attacks non-cereal crops including potato, groundnut, spinach, tomato, cabbage, soybeans, cotton and tobacco.

In Brazil the fall armyworms have a cost of 600 million dollars a year to control.

Dr. Christian Thierfelder, Senior Cropping Systems Agronomist at the International Maize and Wheat Improvement Center (CIMMYT), Southern Africa Regional Office, says poor identification of the pest delayed response to the outbreak in November 2016 because the pest has never been encountered before in Southern Africa.

“Everyone was classifying it [FAW] as a stalk borer or the American bollworm but they were all wrong. This new pest has now been identified as the fall armyworm and people started extensively using pesticides – some of them not yet registered,” Thierfelder told IPS.

“Chemicals are a quick fix and short-term solution to insect pest control and also kill the predators of the pests. This affects the environment and also birds who feed on caterpillars making it important to focus more on alternative ways through biological solutions such as Integrated Pest Management, crop diversification and intercropping.”

The use of IPM has been recommended to deal with insect pests. Integrated pest management is an approach that seeks to minimize and rationalize the use of chemicals.

The approach promotes the use of safer alternatives to pesticides like biocontrol and cultural practices. These include resistant cultivars to control insect pests and diseases, crop rotation and diversification at the plot and landscape, monitoring of insect pests using pheromone traps and seed treatment with beneficial soil rhizobacteria to reduce soil and foliar diseases.

Thierfelder said during extensive field tours in southern Africa, he observed less damage in early planted maize fields under conservation agriculture, intercropped with pigeonpeas or cowpeas and with some trees nearby.

“Here the attack of the fall armyworm was minimal,” said Thierfelder. “This shows that nature can help us in biological pest control as predators can hide in those diversified landscapes and control the pest.”

FAO Sub-regional Coordinator for southern Africa, David Phiri, says the fall army worm has threatened food security in the region because it is new and exposed the need to investment in surveillance systems.

“We do not have ready-made control mechanisms for the fall armyworm and we worry that pesticides used indiscriminately might actually contribute to environmental damage and also contribute to pesticide resistance,” Phiri said.

He added that, “We need to take the issue of monitoring and surveillance very seriously. Historically FAO has been trying to inform and convince governments that they should try to monitor as a matter of course not just monitor when there is a threat because they might be pests and disease coming into the region.”

According to the 2017 FAO report “The future of food and agriculture: Trends and challenges,” public investment is required to catalyze and support private investment. Investment in R&D has to be associated with the development of infrastructure and services to prevent and control the spread of pests and diseases; including trans-boundary ones and mechanisms that help reduce risks.

Rob Vos, Director of FAO’s Social Policies and Rural Institutions Division and one of the authors of the report, told IPS that the threats posed by biological invasions and outbreaks of existing trans-boundary pests highlight the importance of investing in agricultural research to rapidly respond to threats.

“The nature of trans boundary pests requires management on an international scale with countries coordinating their efforts. FAW is a highly mobile pest. The threat it poses to maize production and food security in Africa is not confined to individual countries but affects the entire region,” Vos said.

“Successful management of recurrent and new threats such as FAW is likely to be best achieved through collaboration among governments and international and national organizations.”

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

By Friday Phiri
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.”