Location: Biological Control of Pests Research
Project Number: 6066-22320-010-008-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 15, 2021
End Date: Aug 15, 2023
1. Identification of naturally occurring toxins against red imported fire ants and tawny crazy ants. 2. Identification of pheromones for red imported fire ants and tawny crazy ants. 3. Synthesis of ant toxins, ant pheromones and their analogues for developing control products.
Objective 1: A collective effort of the scientists at NCNPR for the past 20 years has built up a unique natural products repository comprising over 160,000 samples including extracts from terrestrial plants, microbes, and marine organisms, essential oils, column fractions, and purified compounds (naturally occurring compounds and synthetic/semi-synthetic analogues). The majority of these samples have been tested in antifungal and antibacterial assays. Approximately 5000 samples were active against one or more test strains with IC50 values less than 20 mg/mL. These antimicrobial samples (extracts, column fractions, or purified compounds) are more likely to have direct toxic effects on invasive ants or exert properties affecting behaviors of invasive ants compared to other samples in our repository, and would be a good source for screening of new compounds for development of more effective and safer products for invasive ant control. In addition, NCNPR has established a natural product dereplication approach to facilitate bioactive natural products discovery. This approach involves fractionation of natural products extracts into column fractions by high performance liquid. The resultant fractions will be tested for biological activities. The active fractions will be analyzed by ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS) and 1H NMR to dereplicate structurally known compounds or identify structurally novel compounds (Figure 1). This approach has demonstrated its power and advantage in identifying anticancer and antimicrobial compounds from our repository. This approach will be used to rapidly discover structurally novel compounds that have activities against invasive ants. Objective 2: This work will focus on identifying fire ant sex pheromone and trail pheromone of tawny crazy ants. Multiple approaches will be used to identify ant-derived volatile compounds, such as a freeze-thaw SPME method and conventional solvent extraction method. Candidate compounds are then subjected to a series of behavior bioassays to determine their effect on ant trail following behaviors and sex attraction. Objective 3: This work will focus on two candidate compounds from fire ant male alates and fire ant tail pheromone, (Z,E)-a-Farnesene. The male specific compounds will be synthesized using methods and procedures reported in the literature. (Z,E)-a-Farnesene has been demonstrated as a fire ant trail pheromone disrupting the trailing of red imported fire ants. The structural analogues may serve as improved agonists or antagonists to intervene the behaviors of invasive ants. Analogue development or natural product-based design and synthesis has historically demonstrated remarkable successes in pharmaceutical discovery and pesticide development. (Z,E)-a-farnesene will be synthesized using an existing synthetic approach and (E,E)-a-farnesene will also be synthesized using the previously reported one-step synthetic procedure. Their analogue will be designed and synthesized aiming to enhancing activity, chemical stability, and bioavailability.