Spectral sensitivity of North American pest click beetle species (Coleoptera: Elateridae) and their behavioural responses to different wavelengths of light

Click beetles are a large and diverse family that contains several important agricultural pests. With pest populations increasing and effective control options being limited, has arisen a need for novel monitoring and control tactics. One potential tactic is to target the (non-pest) adult beetles before they mate and oviposit, rather than the soil-dwelling larval wireworms which are difficult to control. Recent work suggests that light trapping of beetles may be an option. 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 of 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 ultraviolet (UV) light, with only a broad shoulder in the UV range. These findings have guided the selection of light stimuli for testing behavioral responses of beetles in laboratory and field experiments. Emerging data show a strong preference of various elaterid species to blue and green lights. These results may inform the design of new tools for monitoring and managing pest click beetle populations.