By Edward Makuzva
As chemical solutions falter and ecosystems strain, a natural ally is stepping in. Biological control — using nature’s own predators and pests is quietly transforming agriculture and shaping a healthier, more sustainable future.
One area where significant progress has been made is in the field of biological control — a natural, eco-friendly approach to managing pests and diseases that is revolutionizing the way we protect our crops, ecosystems, and health.
By harnessing the power of nature’s own defenses, biological control offers a promising alternative to chemical pesticides and other hazardous methods, paving the way for a healthier future for generations to come.
Biological control is gaining global recognition as a key tool for promoting healthier ecosystems, safer food production, and long-term agricultural resilience.
As we look toward a future shaped by climate change and ecological challenges, embracing biological control isn’t just an option — it’s a necessity, offering a powerful alternative that works in harmony with nature.
“Through climate-smart, sustainable, and economically viable initiatives, we are actively taking action to protect our environment and promote sustainable agriculture,” said Grace Hama, Acting Head of the Plant Protection Research Institute, during a media familiarization and learning tour on the Biological Control of Invasive Water Weeds (specifically water hyacinth and Kariba weed) at Goromonzi’s Chinyika Dam and Lake Chivero.
Hama emphasized that the institute’s efforts are not only focused on removing invasive species but also on restoring the ecological balance of these critical water bodies, which are vital for local agriculture, fisheries, and community livelihoods. By using environmentally friendly methods such as the introduction of natural predators and biological agents, they aim to reduce chemical reliance and ensure long-term sustainability.
She highlighted the importance of collaborative efforts between scientists, local communities, and policymakers, noting that such partnerships are key to strengthening climate resilience and safeguarding water resources.
The Acting Head added that the success of these initiatives will have ripple effects, improving water quality, enhancing biodiversity, and supporting food security for surrounding populations.
Invasive water weeds are non-native aquatic plants that spread aggressively in rivers, lakes, and dams, disrupting local ecosystems. They usually outcompete native plants, block waterways, reduce oxygen levels, and harm fish and other aquatic life.
These weeds can severely impact water use for irrigation, fishing, hydropower, and even recreation.
Some common examples of invasive water weeds include:
Water hyacinth (Eichhornia crassipes) — floats on water, forms dense mats, blocks sunlight, depletes oxygen.
Kariba weed (Salvinia molesta) — floating fern, spreads fast, especially in calm waters like Lake Kariba.
Maxwell Maturure, Environmental Planning and Monitoring Manager at EMA, revealed that in carrying out their regulatory mandate, the agency is tasked with ensuring that both aquatic and terrestrial ecosystems in Zimbabwe remain free of invasive alien species.
“As defined, invasive alien species are those not native to Zimbabwe. They have been brought into the country for various purposes, most of them for beautification, but they can pose serious risks to local biodiversity and environmental balance.
“And working with the Ministry of Agriculture, Land, Fisheries, Water and Rural Development, we collaborate a lot in terms of activities to support farming and agricultural productivity in the country.
“For production to thrive, we need to have water available. So our effort in this project is to ensure that we support each other to find a solution,” Maturure explained.
Maturure highlighted that the agency is working with the Plant Protection Institute to tackle invasive species like Kariba weed in aquatic ecosystems.
“We are pleased with the progress made so far and will continue expanding efforts, ensuring that landowners and local authorities receive these solutions, as it’s their responsibility to clear invasive weeds from water bodies on their land.
“It’s not the government’s responsibility; by law, it’s the landowners and dam owners who must clear the weed. Sharing information about available solutions is key so they can benefit from environmentally friendly and affordable methods,” said Maturure.
“As a farmer, I have been struggling with the problem of invasive weeds choking our dams. These weeds block the flow of water to my irrigation systems, reduce the dam’s storage capacity, and make it harder to access clean water for both crops and livestock,” said Fidelis Gweshe.
Gweshe added that the weeds grow so fast they can’t keep up, taking over the dam surface, reducing water quality, and causing silt build-up.
“Because of this, my productivity has dropped — I can’t irrigate enough land, crops are wilting, and I’m forced to spend extra money and time just to clear the weeds or find alternative water sources. If this goes on, I fear my yields will keep declining, and the farm won’t survive,” Gweshe explained.
He thanked the Ministry, EMA, and the Plant Protection Research Institute for introducing biological control to tackle invasive weeds in local dams.
“This gives us hope as farmers, as these weeds have been hurting our water supply and productivity. We appreciate their support in helping restore our farming operations,” he said.
Nathan Sangombe, Research Officer responsible for the Biological Control of Invasive Alien Species, revealed that in November 2023, they carried out their first release by introducing 15,000 water hyacinth plant hoppers into Lake Chivero.
“Since then, they have consistently released between 10,000 and 25,000 plant hoppers each month. As a result, the population has now grown significantly, with more than 2,000 plant hoppers per square meter, indicating a steady increase in population density.
However, Sangombe highlighted that they are currently facing challenges due to the onset of the winter season. “Biological control agents like plant hoppers are highly sensitive to low temperatures.
“As we approach the cooler months, we expect the population density of these agents to decline. While the results so far are promising, maintaining an effective level of control during the winter will be difficult because the cooler temperatures can slow down the reproduction and activity of the plant hoppers,” said Sangombe.
Meanwhile, as Zimbabwe confronts the twin pressures of climate change and ecological threats, biological control offers a beacon of hope — a solution rooted in nature, science, and collaboration. While challenges remain, the steady progress made so far signals a future where healthier ecosystems, sustainable agriculture, and resilient communities can thrive side by side.