Spectral sensitivity of North American pest click beetle species (Coleoptera: Elateridae)

Click beetles are a large and diverse family that contain several important agricultural pests. With pest populations increasing, and limited effective control options, has arisen a need for novel monitoring and control approaches. One potential approach is to target the (non-pest) beetle stage before they mate or oviposit, rather than the larval (wireworm) stage (which are soil-dwelling and difficult to work on).  Recent work suggests light trapping of beetles may be an option, and our objective was to use electroretinogram (ERG) recordings to determine the spectral sensitivity of male and female beetles from various elaterid genera. Following 30-min dark adaption, each eye was exposed to 70, 10-nm bandwidths of light, descending in 10-nm increments from 650 nm to 320 nm, and then ascending back to 650 nm. Males and females of all species were particularly sensitive to green light, with green λmax_α values ranging between 516-533 nm. The green λmax_α between female heterospecifics and between male heterospecifics, but not between female and male conspecifics, differed significantly. Overall, the beetles seemed less sensitive to UV light with only a broad shoulder in the ultraviolet range. These findings will inform the selection of light stimuli for future light-based trapping of click beetles, and help us develop new tools for estimating and managing pest populations in the field.