Historical behavioral data disentangle evolutionary and environmental drivers of recent declines in insect attraction to light

Entomologists monitor insect population trends by surveying individuals
attracted to artificial lights at night with the assumption that
flight-to-light behavior is fixed. However, emerging data suggest that
entomological light traps are rapidly losing efficacy relative to other
trap types, and the dramatic growth in anthropogenic light pollution over
the past century has been identified as a probable cause. To investigate
whether decades of strong selection against a conspicuously maladaptive
behavior have decreased insect attraction to light and compromised light
trapping as a survey method, we compared the light attraction of urban and
rural Helicoverpa zea (Boddie) corn earworm moths to historical behavioral
records from 1967. Our results suggest that the flight-to-light response
has remained relatively constant over time but may be strongly influenced
by environmental visual clutter even in seemingly dark habitats. These
findings call into question the use of light traps in long-term surveys,
as the darkness within which they operate is rapidly deteriorating.