Vector-Borne Disease Control: Innovating Larviciding Solutions for Dengue and Malaria

Vector-borne diseases are on the rise globally, and the need for effective vector control has never been more critical. The World Health Organization regularly reports alarming statistics on the spread of these diseases, with The New York Times’ headline “The Mosquitoes Are Winning” becoming an unfortunately apt description of our current situation. Vector-borne diseases, particularly malaria and dengue, continue to pose significant public health challenges worldwide.
Several factors contribute to this growing challenge:

• Urban expansion creating new breeding habitats
• Global movement facilitating the spread of vectors to new regions
• Climate change extending the range and season of mosquito activity
• Insecticide resistance reducing the effectiveness of traditional control methods

These challenges necessitate innovative approaches to vector management that incorporate new chemistries and methodologies.

This post focuses on how larval control, particularly Clarke’s innovative Natular larvicide formulations with their novel active ingredient, fits into Integrated Mosquito Management (IMM) as a powerful, proactive tool to combat vector-borne diseases like malaria and dengue. These specialized formulations are designed to address the diverse mosquito breeding habitats found in both urban and rural environments, offering mosquito control professionals a versatile arsenal for comprehensive vector management programs.

Vector Control: A Comprehensive Approach

An effective vector control strategy must include multiple elements working in concert in order to continuously, proactively counteract mosquitoes at each stage of their lifecycle – and ultimately reduce the overall number of flying, biting adults that can vector disease.

The five basic components of Integrated Mosquito Management (IMM) are:

1. Education – Informing communities about prevention and control
2. Source Reduction – Eliminating mosquito breeding sites
3. Surveillance – Monitoring mosquito populations and disease activity
4. Larval Control – Targeting mosquitoes in their aquatic, larval stages when they are immobile and non-vectoring
5. Adult Control – Managing flying mosquitoes

While insecticide-treated nets (ITNs) and indoor residual spraying (IRS) remain the core interventions for malaria vector control in hot spots outside of the United States, larval source management serves as a crucial supplemental intervention that reduces overall populations of adult mosquitoes, mitigates outdoor biting and disease transmission, and helps manage insecticide resistance.

The Tale of Two Vectors: Aedes aegypti and Anopheles stephensi

Understanding the biology and behavior of disease-carrying vectors is essential for effective control. Two mosquito species of particular concern are Aedes aegypti, a dengue vector, and Anopheles stephensi, a malaria vector.

An. stephensi, originally found in the Indian subcontinent and the Middle East, has shown significant expansion in recent years to several parts of Africa. This is particularly concerning because:

• It has a strong affinity for urban environments
• It thrives in man-made breeding sites
• Its spread increases the risk of malaria transmission in densely populated urban areas

Despite belonging to different genera, Ae. aegypti and An. stephensi share important behavioral similarities:

• Both are highly adapted to urban environments
• Both breed in man-made containers (tanks, pots, tires)
• Both prefer feeding on humans rather than animals
• Both exhibit day-biting and crepuscular (dawn/dusk) activity patterns

These similarities allow for some crossover in control strategies, particularly in larval management approaches.

Innovative Larviciding Solutions: Natular® and its Active Ingredient, Qalcova™ Spinosad

Clarke first introduced Natular® only a decade ago as the first OMRI® Listed larvicide designed with sustainability and green chemistry principles in mind. Since then, we have developed a full portfolio of Natular® formulations in granular, tablet, and liquid formulations for different application purposes and mosquito breeding habitats. Each Natular® formulation contains Qalcova™ Spinosad, derived from a naturally occurring soil bacterium, as its active ingredient.

In all, each Natular® formulation includes the following benefits:

• Offers exceptional control of larvae from the first through early 4th instar stages
• Excellent option for resistance management and rotational use
• Minimal PPE requirements for application
• Green Chemistry active lets you use with confidence in your community

Clarke’s Natular® product line features this innovative active ingredient in multiple formulations designed for different application scenarios:

Single Brood Larvicide Formulations

• Natular® 20EC – Provides 1-7 days of control, ideal for temporary standing water sites

Multi-Brood Larvicide Formulations

• Natular® DT – Bi-layer tablet providing at least 60 days of control, approved for potable water and containers with more than 200 liters of water
• Natular® XRT – Extended-release tablet with up to 180 days of control, ideal for large containers of water and catch basins
• Natular® G30 – High-density granule with up to 30 days of control, ideal for areas with recurring flooding or high-density vegetation

These formulations can be applied using various methods, including by hand, backpack blowers, drones, aerial, and air blast equipment.

Evidence-Based Vector Control: Field Testing Results

Phase 3 evaluation studies conducted in three different epidemiological settings in India (Chennai, Bengaluru, and Nadiad) have demonstrated the efficacy of Natular® formulations against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus.

The results showed consistent performance patterns for all three tested formulations:

1. Natular® 20EC (Single Brood) – Provided excellent initial control with more than 80% mortality with repeated applications necessary for sustained management given its single brood nature
2. Natular® G30 (Multi Brood) – Demonstrated extended control periods of over four weeks with greater than 80% control
3. Natular® DT (Multi Brood) – Showed the longest-lasting efficacy of up to eight weeks, with more than 80% mortality, with a sharp decline in control once the tablet has dissipated, indicating its favorable environmental fate

These field trials confirmed that the same formulations that are effective against Ae. aegypti also performed well against An. stephensi, supporting the potential for unified control strategies in areas where both vectors are present.

Vector Control Beyond Products: The Importance of In-Country Support

Successful implementation of vector control programs requires more than just effective products. Proper implementation demands knowledge of species behavior, habitat preferences, and local conditions to determine the appropriate formulation, application methods, equipment, and timing.

Industry partners should provide in-country support teams to steward the adoption of larval control strategies, assist in training applicator teams, and ensure program success through ongoing technical guidance.

As vector-borne diseases continue to challenge global public health systems, integrated approaches that incorporate innovative tools like Natular® formulations with its Qalcova Spinosad active ingredient can play a vital role in comprehensive management strategies. By understanding the biology of target vectors, selecting appropriate control methods, and providing adequate technical support, we can enhance our effectiveness in combating dengue, malaria, and other vector-borne diseases.

The fight against vector-borne diseases requires continued innovation, collaboration, and commitment to implementing evidence-based integrated mosquito management strategies. As the saying goes, “The world needs mosquito control” – now more than ever.