Masking Agents To Promote Ingestion Of Organic Pest Ant Bait

This STTR Phase I project is focused on novel bait formulations to control red imported fire ants (RIFA). Prior research discovered novel active ingredients (AIs) for fire ant control that successfully caused mortality of RIFA colony workers and their queen under laboratory conditions. However, it was clear in field trials that foraging worker ants would not ingest the bait due to taste aversion. The main objective of this project was to overcome the negative "taste" of the AI to RIFA in the field using taste masking agents that are widely used in human and animal medications. Several techniques for masking the aversive taste of the AIs were evaluated, including tastemasking flavors, e.g., fruit juices, sweeteners (nectars); and phagostimulants (oils, non-dairy milks substitutes). These techniques represent the simplest approach to taste masking, especially in the case of liquid formulations. However, this approach was not successful, since field ants rejected the material provided. Therefore, our focus shifted to a class of complex entrapment agents that are currently used as taste masking agents in the pharmaceutical industry but have not been utilized as adjuvants for insect control. Cyclodextrins have been extensively used for masking bitter drugs by forming inclusion complexes with the drug molecule. Cyclodextrins (?-, ?-, and ?-cyclodextrin) are unique bucket- shaped cyclic oligosaccharides containing at least six D-(+)-glucopyranose units attached by alpha-(1,4)-glucosidic bonds with a molecular structure featuring a hydrophobic cavity and hydrophilic exterior. Taste masking is achieved by inhibiting contact of the bitter AI with the taste receptors. In an aqueous environment, cyclodextrins form inclusion complexes with many lipophilic molecules through a process in which water molecules located inside the central cavity are replaced by either a whole molecule, or more frequently by some lipophilic structure of the molecule. Preliminary and follow-up research for the first time demonstrated the potential of this novel taste masking approach to overcome the taste sensitivity of a pest insect. The research establishes proof of concept for the use of taste masking agents used in human and animal medications to mask the negative taste of the new AIs. Our objective for the STTR phase 1 period is to apply and expand on the knowledge of the pharmaceutical ingredients in overcoming adverse tasting drugs to control RIFA (including sub species) in laboratory and then followed in the field. The use of taste masking agents for insect control and for RIFA control specifically represents new intellectual property. Standard procedures in screening for new insect toxicants dictate that compounds rejected by the target pest are eliminated from further evaluations. Thus, our proposal is unique, and success will provide a new paradigm for active ingredient screening in general. Practically, this will enable field evaluations with the goal of establishing this approach as a platform technology for a broader range of pest ant control products.