From sodium-vapour to LEDs: how an outdoor lighting retrofit affects insects in Singapore

Abstract In the Anthropocene, planet is warming and global biodiversity, including of insects, being lost at an unprecedented rate. One largely urban sustainability solution, shifting to energy-efficient, light-emitting diode (LED) bulbs on outdoor lighting, has impacts insects that are inadequately understood, especially in tropics brightly lit cities. Working Singapore—a highly urbanised light-polluted tropical city-state—we performed a field experiment test hypothesis newly retrofitted LED lights more attractive (i.e., detrimental) compared high-pressure sodium (HPS) lamps they replace. Instead, our sticky traps, which we mounted both light types, caught statistically equal numbers arthropods (individuals families). Traps also attracted proportionally fewer dipterans hemipterans hymenopterans, but these effects were site-specific. Overall, found no support for hypothesis—our findings may reflect differential emissions ultraviolet wavelengths by types and/or possibility insect assemblages with historic exposure pollution not respond as expected retrofit. We caution against extrapolating from impact studies untested contexts highlight need (1) rapidly urbanising (2) tests effectiveness measures limit any negative ecological other lethal sublethal did assess. discuss possible implications ecosystem services conservation.