Microbial Larviciding, Human Health, and the Control of Malaria

Project General Information



Harmful substances and hazardous waste

Persistent Organic Pollutants


OP14 - Program for Reducing and Eliminating Releases of Persistent Organic Pollutants

Demonstration of Innovative and Cost Effective Technologies

Promote sound management of chemicals for the protection of human health and the global environment

Integrating sound chemicals management in GEF projects


The use of DDT in IRS programs is perhaps the most controversial strategy for battling malaria.  Spraying indoor building surfaces with DDT has been highly effective in suppressing malaria transmission in many developing countries, but DDT can also be toxic to wildlife and potentially harmful to humans. However, in those malaria endemic countries where the local vector species remains susceptible to this insecticide, DDT often continues to be the cheapest option for control. Under the Stockholm Convention on Persistent Organic Pollutants (POPs), countries are authorized to elect further use of DDT for malaria vector control when locally safe, effective, and affordable alternatives are not available; countries are obliged to develop and implement action plans to reduce reliance on DDT.

The best way to reduce and eventually eliminate the use of DDT for disease vector control is to develop and implement alternative methods which are safer, effective, contextually appropriate and sustainable. This strategy is embodied both in the mandate of the Global Alliance and in various aspects of the COP5 Decision SC-5/6 on DDT. While much attention has been paid to developing safer chemical alternatives to DDT for insecticide use, the recent COP5 discussions also recognized that the potential contributions of non-chemical environmental-based interventions are significant and should not be overlooked.

Among the non-chemical alternatives mentioned at the COP5, microbial larvicides hold promise as a safe, effective, and environmentally sustainable component of a successful integrated vector management strategy. Historically, chemical larvicides such as Paris Green were used, but these pose significant risks to humans, other non-target species, and the environment. Modern preference for treatment of habitat is with the microbial agent of bacterial pathogens Bacillus thuringinensis (Bti) and Bacillus sphaericus (Bs). Existing studies on microbial larviciding demonstrate not only its significant potential as a safe non-chemical alternative to DDT for disease vector control, but also highlight the immediate need for and value of greater research, particularly on innovative methods of larval source management as well as building a better understanding of the factors and contexts impacting the efficacy of different larviciding strategies.


The current base line is characterized by an absence of specific knowledge and capacity for the formulation of evidence-based national policy elements in Tanzania to promote and support larval source management (LSM) in the early stage of the vector life cycle. As an understudied intervention, the full role of larviciding as a malaria control measure remains to be clarified, especially in rural areas. Both the IVM approach and literature on larviciding make clear that larviciding should never be a stand-alone approach, but rather explored as a promising complement to existing alternative malaria control methods. As the evidence for larviciding as an effective non-chemical malaria control alternative builds, there is a heightened need to contextualize and define its place in the complicated array of malaria control methods. In order for the full potential of larviciding to be realized, key stakeholders and decision-makers need more and clearer information on various parameters of its use, including its impact, cost-effectiveness, necessary coverage levels, potential synergistic effects, and sustainability. 


This project will improve the protection of human health and the environment by promoting safe, sustainable non-chemical malaria control strategies consistent with the successful implementation of the Stockholm Convention on Persistent Organic Pollutants (POPs).  The project responds to the need for the creation of new knowledge and capacity building for improved policy formulation with regards to the deployment of alternatives to DDT for disease vector control. The project’s principal objective is to deepen the evidence base and mechanisms for attacking vector-borne diseases earlier in the vector life cycle through a novel application method of microbial larvicidal agents, as a safe and sustainable malaria control alternative to persistent organic pollutants like DDT. This novel method would enlist farmers to assist in malaria control efforts by applying an optimal larvicide-fertilizer mix to rice fields.

 To accomplish this goal, the project will focus on achieving three main outcomes:

1) Creation of new knowledge about the cost-effectiveness and practicality of farmer application of microbial larviciding as an alternative to DDT and other chemical approaches to malaria control.

2) Improved tools for evidence-based decision-making on the control of vector-borne diseases.

3) Strengthened in-country decision making on IVM for control of malaria and other vector-borne diseases.

These outcomes will be pursued through a range of activities. The project draws on an active and inter-disciplinary network of researchers, practitioners, and policymakers to build research, monitoring, and analytical capacity to make more informed decisions about non-chemical alternative approaches to malaria prevention and treatment.


The project’s objectives will be achieved through proof of principle studies, randomized field experiments, and household surveys and focus group discussions, none of which would be possible without GEF funding for this project. This project adds an environmental component to a set of ongoing agricultural development activities in the lower Moshi area. Additional incremental activities would ensure that the contributions of this project to the evidence base are incorporated into the policy-making process through multiple stakeholder-driven mechanisms which would require GEF funding. The governments of Tanzania and other malaria-endemic countries more broadly as well as CSOs have demonstrated strong commitments to curbing the malaria burden, but are faced with limited resources that constrain their ability to assess, build capacity, and implement non-chemical alternatives to DDT for malaria control. The GEF funding for this project would make it possible to build the evidence base for a novel method of larvicide application as an environmentally-friendly and sustainable non-chemical alternative to malaria control and to build related policy-making capacity. The total cost of the project is the amount necessary to achieve the project’s outcomes, outputs, and health and environmental benefits beyond the current baseline scenario. The incremental cost for the project of 975,000 USD (agency fee not included) is requested of GEF.


National programming and local populations will benefit by the more judicious use of its limited resources for malaria control afforded by the strengthened evidence base.  The project will improve knowledge and the global evidence base regarding feasibility, community acceptance, and effectiveness of microbial larviciding as a support to national policy formulation. The multiple potential benefits of larviciding reiterate the need for a multi-pronged IVM approach to malaria control; a package of varied malaria interventions addressing different stages and aspects of the disease and its management will have a greater impact and may also serve as a powerful strategy for resistance management. In reducing the barriers to acceptance and use of a promising non-chemical alternative to DDT while strengthening in-country decision-making on aspects of integrated vector management, the project will yield global benefits to the environment and human health by addressing the malaria burden and contributing to the phasing out of DDT use and its releases into the environment. The project will also develop guidelines for replication and adaptation of findings to other settings to expand the reach and applicability of the human health and environmental benefits of the project.


The proposed project seeks to establish the viability of a potentially innovative and sustainable novel application method of microbial larvicide agents for the control of malaria. Initial approximations suggest that larviciding is not only cost-effective, but also cost-competitive with other alternative malaria control strategies; while data are sparse, one study estimates the cost of larvicide protection per person per year to be between 0.85 USD to 0.89 USD. Compared with some other prominent alternative malaria control methods, such as LLINs, the successful implementation of larviciding is less susceptible to issues with human behaviors such as uptake and consistent use. Moreover, because mosquito larvae cannot escape the bacteria in water, larviciding is not subject to the vector avoidance issue which has been raised as a concern with IRS and LLIN control methods.  The concept of enabling communities to implement and be engaged in local malaria control interventions has been promoted as a way to scale up IVM programming. Larviciding has been shown to complement other malaria control methods; one study found that combining a larviciding intervention with mass ITN distribution significantly improved control compared to mass ITN distribution alone.

Incorporating a larvicide-fertilizer mix into the routine agricultural practices of farmers has the potential to improve the sustainability and scope of larviciding as an alternative malaria control method, as well as raise community awareness and acceptability. The only significant malaria vector in the proposed study area, Anopheles arabiensis, breeds primarily in rice fields. The proposed application strategy would easily integrate with farmers’ existing practices since vector breeding in the rice fields increases (and would best be targeted) at the intervals during which fertilizer is already routinely applied. Moreover, some research suggests that the application of fertilizer in rice fields engenders a more active vector habitat, so the application of a fertilizer-larvicide mix might further work to reduce the vector population through inhibiting such a mechanism.

Medium-sized Project(MSP)





GEF Trust Fund

Stage Grant to UNEP Grant to other IA Co-Financing UNEP Fee Other IA Fee
$ 1,067,625.00 $ 0.00 $ 3,926,083.00 $ 92,625.00 $ 0.00


The project is consistent with national strategies in Tanzania with regards to reduction of the malaria burden and DDT use. Tanzania ratified Stockholm Convention on Persistent Organic Pollutants in 2004, and produced its National Implementation Plan (NIP) in December of 2005, to cover a fifteen-year period that began in 2006. Within the NIP, the Action Plan for DDT has as its main goal the elimination of the release of DDT into the environment. The NIP expresses the intention of the Ministry of Health to use DDT for IRS. While the Action Plan states than one of its overall objectives is to promote  the research and development of alternatives to DDT (especially IVM strategies), it also identifies as a major constraint the lack of resources for assessing feasibility of alternatives (e.g., in terms of effectiveness, cost, and acceptability). Thus, the project would address both a key objective and a major constraint to the DDT Action Plan set forth in Tanzania’s NIP. NIMR is a partner in the proposed project, consistent with the NIP Action Plan on DDT which indicates NIMR as having lead responsibility for promoting use of alternatives to DDT. More generally, the NIP notes challenges to managing POPs according to the Stockholm Convention include inadequate policy and insufficient institutional capacity (i.e., human resources, technical infrastructure), both of which are issues the project seeks to address.

United Nations Environment Programme (UNEP)



Executing Agency Category
Research/Academic Institution National

Partner Category
Research/Academic Institution National

Name Category Period

Low Risk

A.3 Risk. Indicate risks, including climate change, potential social and environmental risks that might prevent the project objectives from being achieved, and, if possible, propose measures that address these risks to be further developed during the project design (table format acceptable): The willingness of rice farmers to apply the larvicide-fertilizer mix on their fields is essential; the risk that they may not readily support the initiative is mitigated by the strong relationship that KCMC has with the Kilimanjaro Agricultural Training Centre (KATC), a locally-based institute which trains and is trusted by local rice farmers. Another main assumption for successful implementation of the project is that key stakeholders and communities are willing to consider incorporating microbial larviciding into a broader IVM approach to disease vector control. It is further assumed that policy makers will be willing to take into account project-generated data and guidelines on larviciding and LF in making informed policy decisions. The assumption regarding willingness to incorporate microbial larviciding into the IVM approach to malaria control is based on existing studies and reports. The risk that policy makers will be unengaged in or unwilling to take into account project results is minimized due to existing partnerships. The risk that policy makers would be unwilling to use the revised decision-making tool (MDAST) to inform policy decisions is mitigated by the engagement of policy makers in Tanzania and East Africa more broadly in the development and dissemination of the existing decision-making tool.

Not Applicable




Fiscal Year Project activities and objectives met

The project is oriented towards the effective implementation of non-chemical DDT alternatives consistent with the objectives of the Stockholm Convention on Persistent Organic Pollutants (POPs). In particular, the project would contribute to the CHEM-1 focal area objective through the expected outcomes of phasing out of production and use of controlled POPs chemicals, specifically DDT and reducing POPs releases into the environment (GEF V, Strategy Objective 1). The proposed project addresses key aspects of COP5 Decision SC-5/6 on DDT, especially with regards to the need for alternatives to DDT for disease vector control which are safe, effective, affordable, and locally appropriate. The proposed project also directly responds to the mandate and thematic groups of The Global Alliance for the Development and Deployment of Products, Methods, and Strategies as Alternatives to DDT for Disease Vector Control, particularly with regards to building an evidence base to inform policy formulation on non-chemical alternatives to DDT. The project will link with regional efforts by WHO, UNEP, and FAO to promote the adoption of integrated vector management (IVM).

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