Author
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FIELDING, DENNIS |
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Submitted to: Journal of Kansas Entomological Society
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/15/2002 Publication Date: 1/31/2003 Citation: Fielding, D.J. 2003. Windowpane traps as a method of monitoring grasshopper (Orthoptera:Acrididae) populations in crops. Journal of Kansas Entomological Society 76(1): 60-70 Interpretive Summary: During outbreaks, grasshoppers commonly disperse into cropland from areas where their eggs were not disturbed by tillage. Development of management strategies to address this problem has been hindered by a lack of reliable methods for estimating grasshopper densities in crops, where the dense canopy makes it difficult to count grasshoppers. One approach to sampling grasshopper populations within crops involves the use of traps. The objective of this research was to evaluate the utility of window-pane/pan traps to monitor grasshopper invasion of crops. Traps were constructed with a vertical pane of glass and rain-gutter troughs filled with soapy water at the base of both sides of the pane. The traps were effective in indicating population movements during late summer. Grasshoppers apparently were actively attracted to the traps. The traps may not be useful for estimating absolute numbers of grasshoppers, but may be less affected by vegetation type than other methods of sampling, and provide useful information regarding invasion of crops by individual species of grasshoppers. A spin-off of this study may be the development of more effective baits. Technical Abstract: The objective of this research was to evaluate the utility of window-pane/pan traps to monitor grasshopper invasion of crops. Traps were constructed with a vertical pane of glass and troughs of soapy water at the base of both sides of the pane. Transects of the traps were placed in fallow fields, along a roadside, and in barley crops. Density estimates were made with ring counts and species composition was estimated from swee samples. Trap catch was not directly proportional to density estimates from ring counts, although poor weather conditions made it difficult to obtain reliable density estimates. Grasshoppers apparently were actively attracted to the traps. Greater numbers of grasshoppers were captured on the downwind side of the traps when wind direction was consistently from one direction during the sampling interval. Field assays showed that grasshoppers were attracted to aqueous solutions of dishwashing detergent and grasshopper cadavers. The traps may not be useful for estimating absolute numbers of grasshoppers, but may be less affected by vegetation type than other methods of sampling, and provide useful information regarding invasion of crops by individual species of grasshoppers. |
