PROSPECTING THE USE OF ARTIFICIAL LIGHTING FOR INTEGRATED PEST MANAGEMENT

Developments in artificial lighting technologies and greenhouse cladding materials increase the possibilities of manipulating pests and beneficial species. Here, we review the direct and indirect plant-mediated effects of light characteristics on pests and beneficial organisms, focusing on arthropods and their natural enemies. Some examples on the possibilities of managing plant diseases, alone and in combination with pests, with light are also envisioned. Light intensity, photoperiod and wavelength distribution affect plant functions and physical and chemical quality which, in turn, can be reflected in the performance of herbivores. The attenuation of UV-light in HPSL spectrum and in the natural winter daylight of northern latitudes may make plants more vulnerable to pests, whereas the high ratio of red to far-red of HPSLs may act to compensate for the effects of attenuated UV-levels. High red to far red ratio has been shown to result in increased production of plant phenolics and physical defences which, in turn, can negatively influence the performance of some herbivore guilds on plants. Specific spectra produced by LEDs can influence plant quality and hence herbivore performance, but direct effects on arthropods can be even more pronounced, such as the inability of locating host plants by visually orienting pests in red and blue light. Other direct effects of artificial light on organisms include the detrimental effect of UV-C and UV-B on arthropods and fungi, diapause prevention by species-specific wavelengths or photoperiods, attraction to yellow-green wavelengths and polarized light, reduced visibility of prey in specific spectra which, in turn, reduces vector transmitted diseases, interactive effects of light quality and photoperiod on fecundity, species-specific effects of continuous light on the population growth of arthropods and plant-infesting fungi as well as the red light-induced resistance in plants to plant pathogenic fungi. Based on the reviewed literature, the practical implications for IPM as well as knowledge gaps are presented.