Dose-effects in behavioural responses of moths to light in a controlled lab experiment

Insects play a critical role in providing numerous ecosystem services. However, insect diversity and biomass have been declining dramatically, with artificial light being suggested as a contributing factor. Despite the importance of understanding the dose-effect responses of insects to light emissions, these responses have been rarely studied. We examined the dose-effect responses of the greater wax moth (Galleria mellonella L.) to different light intensities (14 treatments and a dark control) by observing their behavioural responses in a light-tight box equipped with a LED light source (4070 K) and infrared cameras. Our findings reveal dose-effect responses to light, as the frequency of walking on the light source increased with higher light intensity. Additionally, moths exhibited jumps in front of the light source and jump frequency increased with light intensity. No direct flight-to-light behaviour or activity suppression in response to light was observed. Based on our analysis of the dose-effect responses, we identified a threshold value of 60 cd/m² for attraction (walking on the light source) and the frequency of jumps. The experimental design in this study offers a valuable tool for investigating dose-effect relationships and behavioural responses of various species to different light levels or specific light sources.