Puerto Rico project to gauge mosquito control method’s potential for disease prevention
By John McPhaul
Puerto Rico will be a pioneer in implementing the vector-control technique of releasing male mosquitoes carrying the Wolbachia bacteria with the launch of a project in late July in Ponce.
The study, part of a series of studies by the Puerto Rico Vector Control Unit of the Science, Technology and ResearchTrust of Puerto Rico, aims to prevent the reproduction of the Aedes aegypti mosquito, a carrier of diseases such as dengue, zika and chikungunya. “In the project in Puerto Rico we are looking for various things and specifically in this project we want to evaluate the effectiveness of this technique to reduce mosquito-borne diseases,” said Dr. Mari- anyoly Ortiz, associate director of the Puerto Rico Vector Control Unit. “Although it has been evaluated in countries and states of the United States, studies have focused on determining whether or not this technique decreases the population of the Aedes aegypti mosquito and [that] has been successfully demonstrated. However, the studies have not focused on demonstrating whether the fact that the number of mosquitoes is reduced causes a reduction in diseases.”
“That is what is expected and we have always worked under that premise,” Ortiz added in a work- shop for the media conducted through the Zoom platform. “This study has the goal of demonstrating with this particular technique that we are monitor- ing the number of diseases. Puerto Rico would be a pioneer in demonstrating this. Furthermore, we are evaluating whether the technique is effective for use in Puerto Rico, which has very different environmental and cultural characteristics from the places where the technique has already been evaluated.”
As detailed, the project will be implemented in 12 areas of the municipality of Ponce, which includes more than 120 communities. The mosquito will be released in some areas to enable comparisons with the areas where it was not released. The mosquitoes will be released from buses or trucks three times a week for a total of 1.5 million mosquitoes weekly. The project will last six months in this initial phase scheduled to start at the end of July.
Ortiz noted that Wolbachia is a bacterium that occurs naturally in six out of 10 of the world’s insects, but it is not found in the Aedes aegypti mosquito. Scientists transferred it from a fly to the Aedes al- bopictus mosquito and found that releasing male mosquitoes with Wolbachia reduces the amount of Aedes aegypti.
The researcher said this is achieved by raising large numbers of mosquitoes with insects carrying the bacteria. Then the males are separated from the females and released into the environment. The males mate with other females and because they are not compatible, the female mosquitoes do not reproduce, which causes a reduction of mosquitoes in the environment. Analysis carried out in states such as Florida, California and Texas indicate that the technique has no effect on other organisms or species in danger of extinction.
“This method is preventive, which means that it is not for stopping an outbreak once it has started,” Ortiz said. “It is [designed] to start reducing the mos- quito population before we have an outbreak. Only male mosquitoes, which do not bite, are released.” She said the technique has experimental permis- sion from the U.S. Environmental Protection Agency (EPA) to be evaluated in Puerto Rico by authorized personnel in specific limited areas. There are also permits from the island departments of Agriculture and Health. Only authorized and trained people can execute the study.
“We have to know that in these first months we are not necessarily going to see a reduction,” Ortiz said. “In Puerto Rico we are starting with a fairly high mosquito population. We hope it will take several months for us to see these effects. In this first phase what we want is to evaluate how many mosquitoes we are going to have to release because we are going to have to compete with those in the environment. [And] [w]e are going to see the logistics of what are the best hours [for release].”
The mosquito is produced by theVerily company, which has a relationship with the Mosquito Mate company, the first to transfer the bacteria from the Aedes albopictus mosquito to the Aedes aegypti. Verily is a subsidiary of Alphabet Co.