2009 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.
The overall goals of this project are to identify chemical compounds that are attractive to pest and beneficial insects and to develop these attractive compounds into practical applications such as insect monitoring tools and environmental friendly insect pest control strategies. Research during FY 09 focused on attractants of several insect species: Emerald ash borer (EAB) (Agrilus planipennis) is a severe invasive pest which threatens to destroy all ash trees in North America; the lesser mealworm beetle (Alphitobius diaperinus), an important insect pest of commercially raised poultry; Galerucella beetles, biological control agents for the invasive purple loosestrife; Diorhabda beetles, biological control agents for the invasive saltcedar; and flea beetles which are mostly pests of food crops with some species used as biological control agents of the invasive leafy spurge plant pest.
Work continued on attractants for the EAB, focusing on host-plant related compounds. EAB antennae were found to be especially sensitive to three compounds present in ash bark in trace amounts suggesting the compounds could be important attractants. These compounds are not commercially available, but progress was made in obtaining at least one of the compounds ((-)-eremophilene) in good amounts by purification of a chemical precursor from a plant oil followed by chemical modification to the desired product. This material was obtained in gram amounts sufficient for field testing and evaluation. A formulation was also developed for a steady release of (-)-eremophilene at relative high amounts, lasting at least a week under field conditions.
Testing of attractants (food volatiles and pheromone) for the lesser mealworm beetle has so far been restricted to experiments in poultry facilities, limiting the number of possible experiments due to the ongoing operations in these facilities. The development of a laboratory wind tunnel behavioral assay has allowed for the year-round testing of attractant parameters.
Our work on attractants for Galerucella beetles, Diorhabda beetles, and flea beetles, are examples where the insects are beneficial biocontrol agents, and the pests are invasive plant species. Attractants that we have developed give land managers a tool to see where the beetles are going and if newly released populations have survived.
An improved method was finalized for synthesizing the aggregation pheromone of Galerucella beetles, which reduced the steps of the synthesis, and increased overall yield. The pheromone has good potential for use, and the new synthesis can make the pheromone more easily available.
Beginning in 2007, a synthetic scheme was devised for the likely 3-D versions of several new flea beetle pheromone compounds. The strategy was first to prepare a good quantity of one particular flea beetle pheromone component that could serve as starting material for many of the additional flea beetle compounds. This work was completed in 2009; chiral and racemic standards of several new flea beetle compounds are now available for chiral gas chromatographic analysis and comparison of synthetic and natural flea beetle pheromone compounds.
ASH-BARK COMPOUND FOR EMERALD ASH BORER. The emerald ash borer (EAB) is an invasive beetle pest from Asia that is causing widespread mortality of ash trees in the U.S. and Canada. Volatile compounds from ash bark can be used as attractants for the detection of EAB. Three compounds in the complex blend from ash bark were sensed particularly well by beetle antennae; however, these compounds are not commercially available. A precursor of one of the compounds has been purified from natural plant oil and obtained in relative large amounts. After chemical transformation of the precursor into the desired ash bark compound and formulation into baits, this compound is now available for field testing. Early detection of adult EAB by means of baited traps is helpful in slowing down the spread of this very destructive ash pest.
LABORATORY WIND TUNNEL BEHAVIORAL ASSAY FOR THE LESSER MEALWORM BEETLE. The lesser mealworm beetle (Alphitobius diaperinus) is a cosmopolitan and abundant pest in poultry houses and stored grains. Testing of attractants (food volatiles and pheromone) for this beetle has so far been restricted to experiments in poultry facilities, limiting the number of possible experiments due to the ongoing operations in these facilities. The development of a laboratory wind tunnel behavioral assay allows for year-round testing of attractant parameters and substantially reduces the time needed to develop the attractants into possible commercially available pest control products. In addition, the bioassay could be useful tool in the search for attractants of other stored grain pest insects.
Bartelt, R.J., Zilkowski, B.W., Cosse, A.A., Steelman, C.D., Singh, N. 2009. Male-Produced Aggregation Pheromone of the Lesser Mealworm Beetle Alphitobius diaperinus (Coleoptera: Tenebrionidae). Journal of Chemical Ecology. 35:422-434.
Robacker, D.C., Aluja, M., Cosse, A.A., Sacchetti, P. 2009. Sex Pheromone Investigation of Anastrepha serpentina (Diptera: Tephritidae). Annals of the Entomological Society of America. 102(3):560-566.
Bartelt, R.J., Cosse, A.A., Zilkowski, B.W. 2008. Early-Summer Pheromone Biology of Galerucella calmariensis and Relationship to Dispersal and Colonization. Biological Control. 46(3):409-416.
Petroski, R.J., Bartelt, R.J., Vermillion, K. 2009. Synthesis of a Dimethylfuran Containing Macrolide Insect Pheromone. Synthetic Communications. 39:1389-1405.
Hossain, M.S., Bartelt, R.J., Hossain, M.A., Williams, D.G. 2008. Longevity of Pheromone and Co-attractant Lures Used in Attract-and-Kill Stations for Control of Carpophilus spp. Entomologia Experimentalis et Applicata. 129:148-156.