Researchers Investigate New Treatment for Combating Disease-Carrying Insects Early

The Problem

Insects such as flies and mosquitoes can carry and spread potentially life-threatening diseases such as malaria, dengue and Zika virus. Mosquitoes and flies have developed resistance to commonly used drugs and traditional methods used to target adult insects, making their larvae an easier target for eradication. With only a few larvicides on the market for mosquitoes, fluralaner could be an effective insect control tool.

The Work

Emily McDermott, assistant professor of medical and veterinary entomology and a researcher for the Arkansas Agricultural Experiment Station, led the work after previously using fluralaner as a medicine for her dog. Fluralaner is an insecticide that prevents insects’ nerve cells from functioning correctly by disrupting their nervous systems, leading to paralysis and death for the insect.

McDermott and Blythe Lawson, a Ph.D. student in Entomology and Plant Pathology, investigated whether the same insecticide could be effective as a larvicide. McDermott and Lawson microencapsulated the insecticide into yeast since the larvae they tested naturally consume yeast and other microorganisms, making this an optimal delivery method. They tested the product on three insect species: the common house fly, or Musca domestica; the Asian tiger mosquito, or Aedes albopictus; and the biting midge, or Culicoides sonorensis.

The Results

The study showed that fluralaner is effective and long-lasting when used to kill larvae. A single application of microencapsulated fluralaner was found to control mosquito larvae for five weeks and midge larvae, or the larvae of a tiny fly, for eight weeks. Through direct treatment of the larvae, the researchers’ approach was area-specific to where they were concentrated and required fewer chemicals. Using fewer chemicals minimizes the need for widespread spraying, effectively mitigating the risk of contaminating waterways and the environment.

The study also found that a higher concentration of the larvicide was needed to kill housefly larvae compared to mosquitoes or biting midges, suggesting that the required concentration correlates to the size of the species, given that houseflies are larger. However, midges were also found to be less sensitive to larvicide than mosquitoes even though they are comparatively much smaller, suggesting that the size component isn’t the only determining factor and insect physiology likely has an impact.

The Value

This work could aid in reducing the populations of disease-carrying pests before they develop into adults, and McDermott thinks the research could lead to the development of a product for household or trash collection site use. Industry partnership building is underway to proceed with a spray technology for commercial application.