Novel Dengue Fever Control Strategy: Adult Mosquitos Deliver Poison To Offspring

world dengue virus distribution image

World distribution of dengue viruses and their mosquito vector, Aedes aegypti, in 2008
Image credit:Centers for Disease Control

Poisoned bait is a very old pest control strategy. Because of high chance of serious collateral damage, controversy inevitably follows. For disease carrying, flying insects, the most common control strategy has been to directly poison breeding areas (standing water). It's difficult to hit all the breeding areas in dense, urban areas And, spraying typically causes collateral damage. Here's a new variation on that strategy, innovative, less costly, and with a far sharper focus.

To control the Aedes mosquitos that spreads Dengue aka "breakbone" fever, SCiDevNet reports that "Researchers working in the Peruvian Amazon used adult Aedes aegypti mosquitoes to carry an insecticide to their own breeding sites, thus killing most larvae found there."

During their life cycle adult mosquitoes must travel between breeding grounds and resting places. Researchers exploited this trait by disseminating a safe and persistent insecticide called pyriproxyfen in the areas where adult mosquitoes rest. The insecticide is neither lethal nor repellent to adults.

The adults then take the insecticide to breeding grounds. This strategy ensures a strong, wide coverage of aquatic breeding sites by treating only a small portion of the adult resting areas because adult mosquitoes move around so much.

Pyriproxyfen (a.k.a. methoprene), the active ingredient used to treat 'mosquito rest stations' in this research, is a common ingredient in flea control medicines used on cats and dogs. USEPA has a methoprene fact sheet (PDF) available which describes the risks and benefits in fairly scientific terms. Here's an important excerpt.

The available information indicates that Methoprene will not result in unreasonable adverse effects on the environment since Methoprene degrades rapidly in sunlight27, both in water28 and on inert surfaces.

Methoprene is also metabolized rapidly in soil and does not leach29. Thus, Methoprene is not expected to persist in soil or contaminate ground water.
Ecological effects Methoprene has been shown to be practically non-toxic to terrestrial species...

Use of this relatively benign larvacide to control such a widespread, misery-causing, and potentially deadly disease as Dengue is a reversal of the historic "exterminator" mindset, which typically matched the most dangerous of pesticides with the most dangerous of disease-causing pests - with wildlife and possibly humans to subsequently take the damaging side effects.

With this ingredient, there is a very low chance of collateral damage becoming an issue. If the costs are low, it'll be a life saver in poor, developing nations (as pictured).

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