Biological control of cassava mealybug

Enhancing Cassava Resilience: Targeted Biocontrol with a Beneficial Wasp

Biological control using Anagyrus lopezi is a method of managing pests naturally without relying on chemical pesticides. In this case, a small wasp from South America, A. lopezi, is used to control the cassava mealybug—a pest that damages cassava crops. The process begins by raising large numbers of these wasps in a controlled environment. Then, they are released into the field where they actively seek out the mealybugs. When a wasp finds a mealybug, it attaches itself and lays an egg on or inside the pest. Once the egg hatches, the wasp larva feeds on the mealybug from the inside, eventually killing it. This approach has been implemented in over 20 countries, reducing mealybug populations by about 90% and protecting cassava crops while saving farmers significant amounts of money.

This technology is pre-validated.

9•7

Scaling readiness: idea maturity 9/9; level of use 7/9

Adults 18 and over: Positive medium

Adult farmers experience increased yields and financial returns, enhancing overall community well-being.

The poor: Positive high

Cassava is a staple food for many low-income populations; effective CM control ensures food security and stabilises incomes for these communities.

Under 18: Positive low

Children benefit from improved household food security and nutrition, contributing to better health and educational outcomes.

Women: Positive high

Women, who often play key roles in cassava cultivation and processing, benefit from reduced labor and increased productivity due to effective CM management.

Climate adaptability: Moderately adaptable

By releasing A. lopezi the problem was solved. No negative impacts on alternate hosts or the environment were ever found. Interestingly the impact of A. lopezi was 90% in all ecological zones (except in dry areas) and permanent, i.e. throughout the year.

Farmer climate change readiness: Moderate improvement

Adopting biocontrol methods reduces reliance on chemical pesticides, leading to more sustainable farming practices that are better suited to adapt to climate change impacts.

Biodiversity: Positive impact on biodiversity

Biocontrol methods preserve and enhance biodiversity by reducing the use of chemical pesticides that can harm non-target species, thereby maintaining ecological balance.

Carbon footprint: A bit less carbon released

In Africa, our travel to release and monitor CM and A. lopezi wass made by airplane and car. The initial impact and initial costs were therefore high, but of short duration only, whereas the continuous impact will have no costs.

Environmental health: Greatly improves environmental health

By minimizing chemical pesticide usage, biocontrol contributes to improved environmental health, reducing soil and water contamination and protecting beneficial organisms.

Soil quality: Does not affect soil health and fertility

Reducing chemical inputs through biocontrol helps maintain soil health by preserving beneficial microorganisms essential for nutrient cycling and soil structure.

Water use: Same amount of water used

While healthier cassava plants resulting from effective pest management may have improved water use efficiency, direct impacts of biocontrol on water use are less documented.

Problem

Severe Crop Loss: The cassava mealybug invaded Africa in the 1970s, decimating cassava crops and drastically reducing yields.
Famine and Food Insecurity: The massive loss of cassava, a staple food, led to widespread famine and severe food shortages.
Economic Hardship: The pest outbreak destabilized the livelihoods of millions of farmers, causing significant economic losses in rural communities.
Ineffective Traditional Pest Control: Conventional chemical and cultural pest management methods were insufficient to control the rapidly spreading mealybug, exacerbating the crisis.

Solution

Natural Enemies: Introducing A. lopezi—a parasitoid wasp from South America—provided a natural enemy to the invasive mealybug.
Targeted Control: The wasp lays its eggs on or in the mealybug; the hatching larvae then consume and kill the pest, directly reducing its population.
Mass Production and Release: After rigorous testing and quarantine, A. lopezi was mass-reared and released across more than 20 African countries.
Effective and Long-Term Impact: Once established, the wasp continuously suppressed mealybug numbers by about 90%, restoring cassava yields and stabilizing food supplies and farmer incomes.
Eco-Friendly Alternative: This biological approach eliminated the need for harmful chemical pesticides, ensuring a safe, lasting, and environmentally sustainable control method.

Key points to design your project

The successful implementation of biocontrol using A. lopezi has significantly reduced pest damage, improved cassava yields, and generated substantial economic benefits at the country level. This large-scale and long-term solution can only be effectively implemented by governments. The introduction, regulation, and monitoring of biocontrol agents require coordinated action, quarantine measures, and national-level policies that individual farmers or private entities cannot manage alone.

Key Steps for Integrating Cassava Mealybug Biocontrol into National Projects

Pest Identification and Assessment

Species Verification: When new or unusual pest outbreaks occur, immediately verify the pest species. With over 1,500 similar mealybug species, it’s essential to confirm that the infestation is due to the cassava mealybug (CM).
Evaluate Contributing Factors: Determine whether the outbreak is exacerbated by factors such as poor cassava maintenance or suboptimal soil conditions (e.g., barren, sandy soil) that favor CM and reduce the efficacy of A. lopezi.
Expert Collaboration: Engage entomology taxonomists for accurate identification and to rule out the possibility of additional pest species.

Technical Support and Regulatory Preparation

Engage with IITA: Contact the International Institute of Tropical Agriculture (IITA) to obtain technical support and guidance on biocontrol implementation.
Quarantine Permit: Initiate the process to secure a quarantine permit from government quarantine authorities. This permit should be supported by comprehensive documentation proving that A. lopezi is non-noxious to local fauna, in line with the FAO Code of Conduct and data from IITA or collaborating entomologists.

Importation, Quarantine, and Field Release

Import Natural Enemies: Arrange for the importation of A. lopezi cultures from regions where they are proven effective, such as South America.
Quarantine Inspection: Ensure that the imported biocontrol agents undergo rigorous quarantine inspections to verify their safety and suitability for release.
Field Deployment: Once approved, release the parasitoids in selected cassava fields under the supervision of local quarantine authorities, following national regulations and best practices.

Monitoring and Impact Evaluation

Establishment Monitoring: Within one year of release, implement monitoring protocols to confirm that A. lopezi has successfully established in the target areas.
Spread and Efficacy: Track the spread of A. lopezi to adjacent fields and assess its impact on cassava mealybug populations.
Crop and Economic Impact: Evaluate the effect on cassava plant health, tuber yield, and the overall economic benefit to local communities using established protocols and in collaboration with IITA.

Cost: $$$ 15 000 USD

Starter cultures, rearing and expert guidance

9.4 billion USD

Estimation of benefits over 40 years (1974–2013) across 27 African countries

IP

Open source / open access

Countries with a green colour: Tested & adopted
Countries with a bright green colour: Adopted
Countries with a yellow colour: Tested
Countries with a blue colour: Testing ongoing

Countries where the technology is being tested or has been tested and adopted
Country	Testing ongoing	Tested	Adopted
Benin	–No ongoing testing	–Not tested	Adopted
Burkina Faso	–No ongoing testing	–Not tested	Adopted
Burundi	–No ongoing testing	–Not tested	Adopted
Cameroon	–No ongoing testing	–Not tested	Adopted
Central African Republic	–No ongoing testing	–Not tested	Adopted
Chad	–No ongoing testing	–Not tested	Adopted
Côte d’Ivoire	–No ongoing testing	–Not tested	Adopted
Democratic Republic of the Congo	–No ongoing testing	–Not tested	Adopted
Equatorial Guinea	–No ongoing testing	–Not tested	Adopted
Gabon	–No ongoing testing	–Not tested	Adopted
Gambia	–No ongoing testing	–Not tested	Adopted
Ghana	–No ongoing testing	–Not tested	Adopted
Guinea	–No ongoing testing	–Not tested	Adopted
Guinea-Bissau	–No ongoing testing	–Not tested	Adopted
Liberia	–No ongoing testing	–Not tested	Adopted
Malawi	–No ongoing testing	–Not tested	Adopted
Mali	–No ongoing testing	–Not tested	Adopted
Mozambique	–No ongoing testing	–Not tested	Adopted
Niger	–No ongoing testing	–Not tested	Adopted
Nigeria	–No ongoing testing	Tested	Adopted
Republic of the Congo	–No ongoing testing	–Not tested	Adopted
Senegal	–No ongoing testing	–Not tested	Adopted
Sierra Leone	–No ongoing testing	–Not tested	Adopted
South Africa	–No ongoing testing	–Not tested	Adopted
Tanzania	–No ongoing testing	–Not tested	Adopted
Togo	–No ongoing testing	–Not tested	Adopted
Uganda	–No ongoing testing	–Not tested	Adopted
Zambia	–No ongoing testing	–Not tested	Adopted
Zimbabwe	–No ongoing testing	–Not tested	Adopted

This technology can be used in the colored agro-ecological zones. Any zones shown in white are not suitable for this technology.

Agro-ecological zones where this technology can be used
AEZ	Subtropic - warm	Subtropic - cool	Tropic - warm	Tropic - cool
Arid	–	–	–	–
Semiarid	–	–	–	–
Subhumid
Humid

Source: HarvestChoice/IFPRI 2009

The United Nations Sustainable Development Goals that are applicable to this technology.

Goal 1: no poverty

The establishment of A. lopezi solved a crisis by halting the cassava mealybug's destruction of cassava fields thereby safeguarding the livelihoods of millions of farmers and contributing to the reduction of poverty

Goal 2: zero hunger

The establishment of A. lopezi solved a crisis caused by the cassava mealybug's destruction of cassava fields, which are the main staple food in these countries.