2010 Annual Report
1a.Objectives (from AD-416)
Objective 1. Identify new fire ant toxins from the defensive chemicals of sympatric ant species and their biosynthesis pathways. Component 5, Problem 5A.
Objective 2. Investigate new fire ant semiochemicals and attractants and feeding stimulants from fire ant natural diets. Component 5, Problem 5A.
Objective 3. Develop formulations using new and existing toxicants and behavior modifying compounds for managment of fire ants. Component 5, Problem 5A.
Objective 4. Develop novel mosquito larvicidal formulations emphasizing efficacy and duration using Bacillus thuringiensis subsp. iIsraelensis ad the model active ingredient. Component 1, Problem 1A, Component 2, Problem 2A; Component 3, Problem 3F.
1b.Approach (from AD-416)
Multidisciplinary approaches are used in developing new ecologically and biologically-based technologies for sustainable management imported fire ants and mosquitoes. New insecticides with new mode of action are investigated by applying advanced concepts and innovative methodologies. In addition to chemistry of the active ingredients, an overall efficacy of an insecticide is enhanced by using proper formulations.
In 2009, we identified new fire ant toxins from the defensive chemicals of other ant species and their biosynthesis pathways, with several significant discoveries made. Defensive chemicals were identified in Rasberry crazy ants (Nylanderia sp. near puben), in the Carribean crazy ant (Nylanderia pubens) and another ant species. A cDNA library was established for all these three invasive ant species, aiming at understanding the biosynthesis pathways of their defensive chemicals. In addition to new venom alkaloids reported last year, new venom alkaloids have been identified in the black imported fire ant and in hybrid imported fire ants. Another invention disclosure application was submitted for using these new alkaloids in managing insect pests.
While investigating new fire ant-produced chemical attractants and feeding stimulants from natural ant foods, the surface chemicals was identified from a weed seed extensively foraged by imported fire ants identified. This could lead to a greatly improved bait and possible commercial use.
We evaluated novel bait formulations using new and existing toxicants and behavior-modifying compounds for management of fire ants. A very promising development was the identification and testing of RNAi-based fire ant bait, the first RNAi insecticide for controlling pest ants. An invention disclosure has been submitted for this RNAi based fire ant bait.
Double-stranded RNA-based Fire Ant Bait. Baits are commonly used in fire ant management. Synthetic insecticides are extensively used in fire ant bait, which is a concern for environmental safety. One alternative is to use species-specific dsRNA. Tremendous effort has been made in developing dsRNA-based approaches in pest insect management. However, to our knowledge, no dsRNA-based method has been developed for controlling red imported fire ants. ARS researchers at Stoneville, MS, developed the first dsRNA based fire ant bait. This technology may lead to a much safer strategy for controlling imported fire ants and significantly reduce the use of the traditional synthetic insecticides.
Ant Derived Chemicals for Fire Ant Control. Synthetic insecticides have been a critical component in pest management, including fire ant control. Unfortunately, with the increased public concern of the risks of using synthetic pesticides, we need safer alternatives. Toxins of natural origin are an attractive alternative to synthetic insecticides because they are more environmentally friendly. ARS researchers at Stoneville, MS, have identified defensive chemicals in the Rasberry crazy ant (Nylanderia sp. near pubens) and established a cDNA library for this ant. These results are important in our attempt to use ant-based defensive chemicals in managing imported fire ants and in understanding the biosynthesis pathways of these chemicals.
5.Significant Activities that Support Special Target Populations
The project, “Effect of imported fire ants on sweet potato production,” benefits a socially disadvantaged/limited resource/historically underserved producer.
Garlapati, R.B., Cross, D.C., Caprio, M.A., Sabanadzovic, S., Chen, J. 2010. Phenotypic and Genotypic Characters Associated with Polygyne Hybrid Imported Fire Ant. Midsouth Entomologist. 3:26-32.
Chen, J., Shang, H., Jin, X. 2009. Response of Solenopsis invicta (Hymenoptera: Formicidae) to potassium oleate water solution. Insect Science. 17:121-128.