Developing yeast microencapsulated fluralaner as a larvicide for vector control

Fluralaner is a novel active ingredient in the isoxazoline class of insecticides. It is currently labeled in the US as a companion animal ectoparasiticide, but has a broader target range than fleas and ticks. One limitation of fluralaner is that appears to have limited cuticular penetration. In its labeled form, it is formulated as a systemic, and ingested in the blood meal. We hypothesized that fluralaner could be a useful tool for larvicide applications for controlling pestiferous fly species if it could be formulated in a manner where the AI would be ingested. Yeast microencapsulation (YME) is a low cost strategy to improve the delivery and stability of various chemical compounds. As the larvae of many insects, including mosquitoes and house flies, readily consume yeast in the environment, we felt that YME would be an ideal strategy for formulating fluralaner as a larvicide. We developed and validated a proprietary formulation process for fluralaner and successfully encapsulated it in S. cerivisiae yeast. This formulation was tested against Musca domestica, Aedes albopictus, and Culicoides sonorensis larvae in lab and semi-field trials. Exposure to YME fluralaner significantly reduced the survival of all three species, and provided excellent control under semi-field conditions for 2-8 weeks. YME fluralaner also outperformed available COTS products for Ae. albopictus. YME fluralaner has strong potential to become another tool in our arsenal for fly and vector management.