2007 Annual Report
1a.Objectives (from AD-416)
Expeditiously identify chemical attractants (e.g., pheromones and plant
volatiles) for agriculturally important insect species (either pests or
biocontrol agents for weed or insect pests) for which such knowledge is
lacking or incomplete, determine the biological and environmental
parameters for natural emission of the compounds, and synthesize or
otherwise obtain them in quantities sufficient for field use. Characterize the behavioral responses toward the identified compounds under field conditions, with special consideration to the development of practical management tools.
1b.Approach (from AD-416)
Seek pheromones and host-plant related attractants for selected insect species. Species studied will include, but not be limited to, Diorhabda elongata (a biocontrol agent of saltcedar), Galerucella calmariensis (a biocontrol agent of purple loosestrife), and various flea beetle species (including vegetable crop pests and also biocontrol agents of leafy spurge). Collect volatiles from male and female insects and from host plants and analyze these by gas chromatography, mass spectrometry, and electrophysiology (“electroantennograms”). Those compounds that are emitted by just one sex and that are detected with great sensitivity by the insect antennae are likely to be pheromone components. Similarly, host plant compounds with high antennal sensitivity are potential attractants. Identify the structures of these key compounds using mass spectrometry, nuclear magnetic resonance spectroscopy, chemical tests, and other appropriate methods. Synthesize the compounds using the methods of organic chemistry or otherwise obtain them in bulk from botanical or other sources. Use techniques such as “sticky traps” or other trapping methods to evaluate the attractiveness of synthetic compounds under field conditions, relative to controls and also to live insects. Characterize the behavior toward the attractants under laboratory conditions, if possible. Develop the newly identified attractants as practical insect management tools, for monitoring or manipulating populations of the insects under consideration. For key pheromones, such as those of nitidulid beetles, develop new synthetic schemes suitable for commercial pheromone production.
Research during FY 07 was concentrated in three areas, emerald ash borer attractants, flea beetle pheromones, and lesser mealworm beetle volatiles.
Work on the emerald ash borer (Agrilus planipennis; EAB), a severe invasive pest from Asia, was on beetle-produced compounds (as summarized in the accomplishment section) and also on host-plant-related compounds. Using the "electroantennogram" technique coupled with gas chromatography, beetle antennae were found to be extremely sensitive to two compounds, both sesquiterpenes, present in ash bark in trace amounts. Efforts continue to isolate and identify the compounds. Goals are to acquire amounts sufficient for field testing and to evaluate whether they can be effective baits in traps for beetle detection.
Progress was made on the synthetic and analytical chemistry of flea beetle pheromones. Compounds previously identified from Phyllotreta spp. (pests of crucifer crops) and Aphthona spp. (biocontrol agents for leafy spurge) are being synthesized in enantiomerically pure form. Five of these are complete, as are immediate precursors for the remaining eight. These compounds will serve to verify previous identifications and to allow field testing in accordance with the CRIS project plan. Analytical methods were developed to distinguish among the eight geometrical isomers of 2,4,6-nonatrienal. The pheromones of the eggplant flea beetle (Epitrix fuscula) and other members of the genus include one or more of these rather labile aldehyde; and the new analytical methodology will make possible a chemical comparison of the pheromones of these closely related beetles.
Finally, pheromone research was begun on the lesser mealworm beetle (Alphitobius diaperinus). This cosmopolitan species is a serious pest in poultry operations, causing structural damage in farm buildings, harboring disease organisms affecting fowl, and developing large populations in feed and manure. A pheromone could become a useful tool in beetle management. During FY 07, studies revealed that mature males can emit relatively large amounts of four compounds that are lacking from females and young males. The chemical structures are under investigation, and the biological function(s) and potential uses of the compounds will be studied.
Emerald ash borer (EAB) lactone. Emission of chemicals from adult EAB beetles was studied in the laboratory to screen for possible pheromones. Improved detection/monitoring tools are urgently needed for the EAB. Long-range pheromones are known in many insect species and can serve as potent, practical baits in monitoring traps, yet no pheromone information existed for this pest. A compound was discovered that has properties consistent with a pheromone (is emitted almost exclusively from females and is readily detected by the beetle antennae), was identified (belongs to a class of compounds called lactones), and was synthesized. The exact function of the lactone in EAB biology remains unknown; but based on initial field studies during 2007, it apparently does not serve as the desired long-range attractant. This research addresses National Program 304 Quarantine and Crop Protection; Component 4--Postharvest, Pest Exclusion, and Quarantine Treatment; Problem Area 4d: Fundamental Biology and Ecology of Exotic Pests.
5.Significant Activities that Support Special Target Populations
|Number of web sites managed||1|
|Number of non-peer reviewed presentations and proceedings||5|
|Number of newspaper articles and other presentations for non-science audiences||2|
Bartelt, R.J., Cosse, A.A., Zilkowski, B.W., Fraser, I. 2007. Antennally active macrolide from the emerald ash borer Agrilus planipennis emitted predominantly by females. Journal of Chemical Ecology. 33:1299-1302.
Petroski, R.J., Bartelt, R.J. Direct aldehyde homologation utilized to construct a conjugated-tetraene hydrocarbon insect pheromone. Journal of Agricultural and Food Chemistry. 55:2282-2287.
Bean, D.W., Wang, T., Bartelt, R.J., Zilkowski, B.W. 2007. Diapause in the leaf beetle Diorhabda elongata (Coleoptera: Chrysomelidae), a biological control agent for tamarisk (Tamarix spp.). Environmental Entomology. 36(3):531-540.
Bartelt, R.J., Hossain, M.S. 2006. Development of synthetic food-related attractant for Carpophilus davidsoni and its effectiveness in the stone fruit orchards in Southern Australia. Journal of Chemical Ecology. 32:2145-2162.
Cosse, A.A., Bartelt, R.J., Zilkowski, B.W., Bean, D.W., Andress, E.R. 2006. Behaviorally active green leaf volatiles for monitoring the leaf beetle Diorhabda elongata, a biocontrol agent of saltcedar. Journal of Chemical Ecology. 32:2695-2708.
Zilkowski, B.W., Bartelt, R.J., Cosse, A.A., Petroski, R.J. 2006. Male-produced aggregation pheromone compounds from the eggplant beetle (Epitrix fuscula): identification, synthesis, and field bioassays. Journal of Chemical Ecology. 32:2543-2558.