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Insect Sampling


Insect surveys estimate the relative biomass available as insects for food. Transect sweeps (see photo at right) and pit-fall traps are used to collect specimens. Insect sweeps are conducted along eight randomly chosen transects three times a year. Pit-fall traps are buried in plots in the Southwest location to characterize the diversity of ground insects. Methods are being tested to expand the sampling effort to more accurately determine the effects of harvest on pollinators. 
We designed a new process, called Quantitative Insect Sampling Technique (QuIST), for assessing sweep net collection comprehensiveness and efficiency. The objective was to collect all insects within a column of prairie and compare the results to the samples gathered from sweep nets. The enclosed screen "tent" was placed on random points and relatively sealed to prevent any insects from escaping. All of the vegetation was cut inside QuIST, bagged and sorted. A modified leaf-blower was used to vacuum remaining insects from the prairie floor and those flying in the tent. 



QuIST was tested at the southwest sampling site and used to calibrate the other collection methods across sites. Insect samples were frozen and then sorted into taxonomic groups by laboratory specialists. To further complement the QuIST sampling, a trial session of pit-fall traps took place in 2009 to provide preliminary data used in selecting the best method.