About This Project

The mosquito A. aegypti is the main vector for dengue and zika viruses. This mosquito has developed resistance to common insecticides. We've shown that a biological control agent (a roundworm) can kill 85-100% of mosquito larvae. As a follow-up study we need to submit the roundworm to an “acid test” to verify its efficacy in urban settings. If this bioagent passes the test this could be another method to control the mosquito and reduce the spread of dengue, zika and urban yellow fever viruses.

Ask the Scientists

What is the context of this research?

A. aegypti is the most important mosquito to public health worldwide because it is the main vector for dengue, zika and urban yellow fever viruses. Health officials normally use insecticides to control the mosquito population, but A. aegypti has developed insecticide-resistance(1).

We know that entomopathogenic roundworms (ERs) are effective at controlling a range of insect pests in agricultural and urban settings(2). During a survey in the Atlantic Forest of Brazil, we isolated an ER from bromeliads, which is often where female mosquitoes lay their eggs.

Through an unpretentious assay, two of our graduate students noticed that this ER killed most A. aegypti larvae. This serendipitous discovery made us look more attentively at ERs as potential biocontrol agents of mosquitoes.

What is the significance of this project?

Through a series of assays, our research group confirmed the potential of some ERs as biocontrol agents of A. aegypti(3). The ER Heterorhabditis indica LPP35 ranked first, what led us to further investigate the parameters that determine its efficacy against mosquito larvae.

In a follow-up study(4), H. indica LPP35 killed 85-100% of the mosquito larvae when introduced to containers of different sizes and shapes that mimic natural mosquito oviposition sites.

This project is the natural next step. We must submit H. indica LPP35 to a "acid test" to confirm its efficacy in household small water reservoirs that are typically infested by mosquito larvae.

What are the goals of the project?

The "acid test" will be conducted in roof water drains, indoor and outdoor floor drains, used tires, pot saucers and small water reservoirs.

Each container, filled with water, will receive 15 mosquito larvae and 1,500 roundworms (this rate has been found to be optimal). A voile fabric attached to the containers will prevent the emergence of adult mosquitoes should the larvae evade infection by the roundworm. Killing of the larvae will be assessed 7 days later.

Since the roundworm is able to reproduce in the dead larvae, it may establish a resident population in the containers, minimizing the need for reapplications by health officials. The efficacy of the resident roundworms will be assessed through re-applications of mosquito larvae and new assessments of efficacy.