How to disguise evolutionary traps created by solar panels

Photovoltaic panels are the most rapidly growing source of sustainable energy, but are also sources of polarized light pollution that can mislead aquatic insects into thinking they represent natural waterbodies. Aquatic insects are commonly attracted away from natural water bodies to lay their eggs upon solar panels where they fail to hatch, a phenomenon called an evolutionary trap. Previous work demonstrates that the addition of white, non-polarizing gridding with 2–20 mm line width to solar panels can effectively ‘disarm’ this type of evolutionary trap, rendering it less attractive to three families of aquatic insects. However, the geographic and taxonomic breadth of the efficacy may be limited, and the economic cost associated with reducing the black solar-active area of solar panels has not yet been quantified. We designed a field experiment to test whether line width or density is more important in reducing the maladaptive attraction of aquatic insects to simulated solar panels, and expanded the geographic and taxonomic breadth of testing this approach to disarming evolutionary traps. We found that line width could be manipulated to strongly reduce attraction by all taxa. The effective line width was between 1 and 5 mm, indicating that solar panel-induced evolutionary traps can be disarmed with a more modest reduction in solar-active area than was previously assumed. Interruption of attraction through the addition of non-polarizing surface patterns appears to be a fundamental aspect of aquatic insect interpretation of environmental polarized light signals that can be used to disguise evolutionary traps.