Controversial Hormone Used In New Mosquito Trap To Aid In Fight Against Zika Virus

BY ON 06/04/17 AT 5:58 PM

Legitimate concerns of the average American traveler include the high cost of flights and cumbersome airport security, but now that mosquito season is approaching — you can add the Zika virus to that list.

Scientists at the Centro de Investigaciones de Plagas e Insecticidas in Argentina have created a trapping apparatus that can be used to observe and regulate the Aedes aegypti mosquito, a breed that carries a myriad of diseases such as Zika, dengue, chikungunya and yellow fever.

The Zika virus drew global concern in late 2015 when an increase in babies born with microcephaly — unusually small heads and brain damage — was seen in northeastern Brazil months before and during the subsequent epidemic of the mosquito-carrying disease in the area. The World Health Organization announced a global health emergency in February 2016.

As described in the Journal of Medical Entomology, the “ovitrap” device is shaped like a small cup and is composed of a low-density polyethylene plastic mixed with the larvicide pyriproxyfen, which prevents mosquito development.

“In addition to their value for vector surveillance, various ovitrap devices have been evaluated as tools for suppressing Aedes aegypti populations,” the study said.

When the cup is filled with water, the larvicide gets released from the plastic. Female Aedes aegypti mosquitoes favor small containers to deposit their eggs such as pots and tires that contain water, making the trap a desirable egg-laying location.

Although used for years as a method of mosquito testing, the use of plastic containing the larvicide pyriproxyfen is new to the fight against mosquitoes. In their study, the researchers performed tests with the trap on laboratory-raised Aedes aegypti mosquitoes and concluded the larvicide was 100 percent effective in halting development.

Pyriproxyfen is equivalent to a hormone that prevents insect larvae from developing into adults. It is one of the several pesticides suggested by the WHO Pesticide Evaluation Scheme.

The hormone has gained notoriety through false reports by activists who claimed it caused microcephaly, a rare neurological disorder in which an infant is born with a head circumference that is abnormally small. It is considered a developmental defect of the brain and is a consequence of abnormal brain development during pregnancy or possibly due to the restriction of brain growth after birth.

However, that claim was proven false by a study conducted by the Entomological Society of America. The Brazilian government also has indicated the relationship between the use of pyriproxyfen and microcephaly has no scientific backing.

Research by the NatureResearch Journal shows ovitraps are made to replicate natural breeding areas and to attract egg-laying female mosquitoes. The traps have been used for years as a subtle, low-cost, surveillance device for discovering container-inhabiting mosquitoes and for keeping a relative measure of time-based changes in adult abundance. In addition to their value for vector surveillance, various ovitrap devices can be used to suppress aegypti mosquito populations.

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