Canopy spectral reflectance: A potential monitoring tool for sugarbeet root maggot, Tetanops myopaeformis

Sugarbeet root maggot (SBRM), Tetanops myopaeformis (von Roder) (Diptera: Ulidiidae), is the most damaging insect pest of sugarbeet production in Minnesota and North Dakota.  Monitoring for this pest requires pulling sugarbeet roots and examining them for surface feeding damage. A less damaging and more accurate method of assessing populations would be useful to both producers and field scouts.  Both visible and Near Infrared (NIR) imagery has long been used to assess plant stress, including insect feeding in many species.  The use of remotely sensed plant health metrics may provide a rapid and accurate method of evaluating the impact of SBRM on sugarbeet stands.  Imagery from a TetraCam ADC (multi-spectral NIR camera) of replicated controlled and uncontrolled SBRM plots was used to construct Normalized Difference Vegetation Indices, these indices were compared across treatments and a significant difference was found between plots with low populations of SBRM and uncontrolled plots with high SBRM populations. A CropScan multispectral radiometer were used to construct reflectance curves of plot canopies and while SBRM feeding did seem to depress reflectance in expected wavelengths, there was also a significant variety effect in results.