2013 Annual Report
1a.Objectives (from AD-416):
Objective 1. Use established procedures to obtain basic understanding of eicosanoid-mediated immune signaling in pest (squash bug, Anasa tristis) and beneficial (spined soldier bug, Podisus maculiventris) insect species.
Objective 2. Generate new knowledge for future deployment of dsRNA to silence genes involved in immune signaling, particularly eicosanoid-mediated signaling, in a pest insect (squash bug, Anasa tristis) and test for species specificity using a beneficial insect (spined soldier bug, Podisus maculiventris).
1b.Approach (from AD-416):
1) Determine the influence of infection on PLA2 activity in immune tissues from squash bugs and spined soldier bugs;.
2)Characterize and determine the influence of infection on prostaglandin production in immune tissues from squash bugs and spined soldier bugs;.
3)Test the idea that prostaglandins and other eicosanoids mediate cellular reactions to infection;.
4)Design dsRNA to silence genes involved in immune signaling; and.
5)Determine the influence of dsRNA on immune signaling in intact squash bugs.
For objective 1a we continued characterization of an enzyme (phospholipase A2) responsible for signaling infections in a lepidopteran pest, the tobacco budworm and moved far beyond the progress reported for FY12. We identified the gene and characterized the enzyme. This work is the basis for identifying and characterizing a similar gene in squash bugs.
For objective 2B we formed a partnership with a biotechnology start-up firm in St. Louis, Missouri to jointly design, synthesize and evaluate their innovative gene silencing tool. The design and synthesis are complete and we will begin evaluation, blocking expression of a midgut enzyme that is known to be lethal in other insect species.
Discovery of a novel mechanism of gene regulation in insect development. Long-term agricultural sustainability is severely threatened by widespread use of classical insecticides. Threats include increasing resistance to insecticides and sharply decreasing environmental quality. Insect pests consume or destroy about 15% of the world’s human food production, which is driving research to invent and develop new insect pest management technologies. Recent advances in basic knowledge of insect genetics provide the basis for new pest control strategies, particularly genetic control strategies. ARS researchers, working in a collaborative international team, discovered a novel gene that acts in insect development. Silencing expression of this gene blocks insect development. This work provides a new target for genetic control of insect pests. Research scientists will use this finding to develop similar approaches to genetic control of large crop systems. Ultimately, this research will benefit growers who produce major food crops and the people who consume healthier foods.
Established a new insect cell line from the red flour beetle. The red flour beetle is a destructive pest of stored grain. The complete genome of this pest has been sequenced and annotated, which has elevated this pest to the status of a model insect for basic and applied research. A major short-coming, however, is the lack of a functional cell line (a system of growing the insect cells in culture) established from the red flour beetle. Working with established cell lines markedly accelerates research progress. ARS researchers in Columbia, Missouri, in collaboration with ARS researchers in Manhattan, Kansas, established a cell line from the red flour beetle and characterized the cell line at the molecular level. The cell line has been shared with several ARS, university, industrial and international laboratories. Research scientists use this cell line to facilitate several lines of research progress. Ultimately, this research will benefit grain storage operations and the people who rely on grain-based foods.
Discovery of central element in cellular immune signaling mechanism. Application of classical insecticides has introduced severe problems into agricultural sustainability. The concept of biological control of insects is a potentially powerful alternative to classical insecticides. Biological control is based on the idea that direct application of insect-specific pathogens and parasites can reduce pest insect populations and the economic damage due to pest insects. The problem, however, is the efficiency of these organisms in biological control programs is limited by insect immune defense reactions to challenge. One approach to improving the efficiency of biocontrol agents would be to somehow disable insect immune reactions to viral, bacterial, fungal and parasitic infections. With this goal, ARS researchers in Columbia, Missouri, working in an international collaborative team, identified the central element in cellular immune signaling that is responsible for linking three entirely different biochemical signals to produce coordinated cellular reactions to infection. This discovery identifies a new specific target that will be useful to scientists working to develop new biological control technologies. The ensuing improved biological control methods will benefit a wide range of agricultural producers and consumers by supporting the long-term sustainability of agriculture.
Sun, B., Jiang, X., Zhang, L., Stanley, D.W., Luo, L., Long, W. 2012. Methoprene influences reproduction and flight capacity in adults of the rice leaf roller, Cnaphalocrocis medinalis (Guenee) (Lepidoptera: Pyralidae). Archives of Insect Biochemistry and Physiology. 82(1):1-13.
Zhang, X., Chen, M., Ma, X., Zhao, X., Wang, J., Song, Q., Stanley, D.W., Shao, H. 2013. Suppression of AcMNPV replication by adf and thymosin protein up-regulation in a new testis cell line, Ha-shl-t. Archives of Insect Biochemistry and Physiology. 82(3):158-171.
Park, J., Stanley, D.W., Kim, Y. 2013. Rac1 mediates cytokine-stimulated hemocyte spreading via prostaglandin biosynthesis in the beet armyworm, Spodoptera exigua. Journal of Insect Physiology. 59:682-689.