Location: Chemistry Research2010 Annual Report
1a. Objectives (from AD-416)
Develop improved methods for monitoring efficacy of control of stored product insect pests resulting from use of alternatives to the use of methyl bromide as structural fumigants in stored product facilities and provide improved methods population monitoring and for integrated pest management in food facilities such as wheat flour mills, rice mills, pet food facilities, and associated warehouses with the goal of eliminating the need for use of methyl bromide as a fumigant in these facilities.
1b. Approach (from AD-416)
Biological assay guided fractionation of naturally produced chemicals collected using various techniques will be used. Chemicals will be identified by chromatographic, spectroscopic and microdegradative methods and synthesized using organic synthesis procedures. Synthetic samples will be formulated using physicochemical principals so as to release ratios and amounts of chemicals identical to those released by natural sources and tested in biological assays.
3. Progress Report
Progress in understanding the behavior of the red flour beetle Tribolium castaneum, a major pest of stored products and the pest of greatest concern in flour mills, has led to development of a new insect trap for monitoring this pest and other stored product insects. The trap promises to be a highly effective component of insect monitoring systems for flour mills, and for food processing plants in general. These programs, which would include inspections as well as trapping, are critical to implementing the methyl bromide alternatives envisioned by Component 2A of the National Program Action Plan. The alternatives include integrated pest management (IPM) and alternative fumigants, which would be applied as needed rather than on a calendar basis. Effective pest monitoring is critical to the success of such systems, because monitoring provides necessary guidance for timing and targeting pest control applications. The research behind the trap design examined behavioral responses of T. castaneum to light, chemical volatiles, and tactile stimulation in order to identify traits that could be used to lure the beetles into traps. Experiments with light of various wavelengths showed that T. castaneum is strongly attracted to light-emitting diodes (LEDs) emitting near ultraviolet light, and that traps with these lights as the only attractant were very effective in capturing beetles. Experiments were done with volatile chemicals emitted by T. castaneum to determine their influence on formation of beetle aggregations. None of the volatiles examined increased the effectiveness of the previously identified aggregation pheromone that is available commercially. Nor were individuals attracted to groups of T. castaneum or to volatiles collected from these groups. Volatiles collected from groups of T. castaneum at different densities showed a clear relationship between density and rate of volatile emission; they also revealed an inverse correlation between emission of aggregation pheromone and emission of benzoquinones. Tribolium castaneum was found to detect benzoquinones and to be repelled by them, suggesting that increasing concentrations of these compounds may trigger dispersal. It was noted during the experiments that T. castaneum shows a strong tendency to follow edges and remain in tight spaces (positive thigmotaxis). The observations of light, chemical, and tactile responses led to design of a pyramid-shaped trap with fins that guide insects into a central pitfall. Trap efficiency is enhanced by LEDs emitting ultraviolet light and a septum (optional) that releases the beetle’s aggregation pheromone. In competitive tests with a standard trap baited only with aggregation pheromone, the new trap captured 20 x more beetles. In another test, it recaptured up to 1/3 of the beetles released in a darkened shed (trap efficiency of about 33%). With efficiency this high, the new trap is promising as a monitoring tool for use in alternative pest management systems.
Campbell, J.F., Toews, M.D., Arthur, F.H., Arbogast, R.T. 2010. Long Term Monitoring of Tribolium castaneum in Two Flour Mills: Seasonal Patterns and Impact of Fumigation. Journal of Economic Entomology. 103: 991-1001. DOI: 10.1603/EC09347.