DOI: 10.5061/dryad.9zw3r22v9
title: Historical behavioral data disentangle evolutionary and environmental drivers of recent declines in insect attraction to light

description: 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.
description: # Historical behavioral data disentangle evolutionary and environmental
 drivers of recent declines in insect attraction to light Dataset DOI:
 [10.5061/dryad.9zw3r22v9](https://doi.org/10.5061/dryad.9zw3r22v9) ##
 Description of the data and file structure 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. ### Files and variables #### File: code.Rmd
 **Description:** scripts for data analysis #### ELF Files Each CSV file
 (XX-scene00x_blur3.csv) was generated from an experimental tunnel and
 corresponds to one of two study sites: Harvard Forest
 (HF-scene00x_blur3.csv) and Lakeville (LV-scene00x_blur3.csv). The data
 production followed the procedures put forth by Nilsson and Smolka (2021)
 and the Konstanz ELF approach (github.com/Foztarz/ELF_Konstanz). Within
 the parent directory, six subfolders represent six tunnels in total. Each
 subfolder contains three environmental photographs in .NEF format, taken
 at different exposure levels (EV), following the standard workflow
 outlined in Nilsson and Smolka (2021). The resulting dataframe contains
 information on the mean, std, median, 25th percentile, 75th percentile,
 min, max, 2.5th percentile and 97.5th percentile intensity (in lit -- see
 Nilson and Smolka 2021) values across all red (row 2), green (row 3), and
 blue (row 4) color channels as well as their combination (white - row 5).
 The elevation-dependent vertical gradients for each channel within the
 image are then given in the rows below (7+). #### File:
 LV-scene001_blur3.csv **Description:** processed ELF image from inside 1
 of 4 tunnels in Lakeville, ME (2024) #### File: LV-scene002_blur3.csv
 **Description:** processed ELF image from inside 1 of 4 tunnels in
 Lakeville, ME (2024) #### File: LV-scene003_blur3.csv
 **Description:** processed ELF image from inside 1 of 4 tunnels in
 Lakeville, ME (2024) #### File: LV-scene004_blur3.csv
 **Description:** processed ELF image from inside 1 of 4 tunnels in
 Lakeville, ME (2024) #### File: HF-scene001_blur3.csv
 **Description:** processed ELF image from inside 1 of 2 tunnels in
 Petersham, MA (2023) #### File: HF-scene002_blur3.csv
 **Description:** processed ELF image from inside 1 of 2 tunnels in
 Petersham, MA (2023) #### File: experiment_sites.csv
 **Description:** latitude and longitude of the sites where trials were
 conducted in 2023 and 2024 ##### Variables * year: year experiment took
 place * state: state in which experiment took place * site: site name
 where experiment took place * latitude: latitude of experiment site *
 longitude: longitude of experiment site #### File: generation_info.csv
 **Description:** information on caterpillar cohorts ##### Variables *
 state: state where caterpillars were collected * site: collection site
 name * ID: collection site abbreviation * latitude: latitude of collection
 site * longitude: longitude of collection site * year: year of trial (2023
 or 2024) * generation: whether wild-caught caterpillars reared to adults
 were tested (P) or their lab-reared progeny (F1) #### File:
 colony_metadata.csv **Description:** information on caterpillar collection
 sites ##### Variables * state: state where caterpillars were collected *
 site_name: collection site name * latitude: latitude of collection site *
 longitude: longitude of collection site * light_level: estimated light
 pollution in mag/arcsec^2, from lightpollutionmap.info * coauthor:
 initials collaborator who collected caterpillars * old.state: former
 collection site name #### File: light_statistics_MA-ME.csv
 **Description:** light pollution levels at varying buffer distances around
 experiment sites ##### Variables * mean: mean light pollution intensity in
 nW/cm^2/sr * median: median light pollution intensity in nW/cm^2/sr * min:
 minimum light pollution intensity in nW/cm^2/sr * max: maximum light
 pollution intensity in nW/cm^2/sr * sd: SD of light pollution intensity in
 nW/cm^2/sr * n: disregard * radius: radius around experiment site in m *
 state: state where experiment took place #### File: trial_data.csv
 **Description:** moth attraction data from experimental trials #####
 Variables * Date: trial date * Starting_time: time of evening when trial
 began * Box: tunnel ID * Section: location within tunnel (UV: close to the
 light; M: middle section; F: far from the UV light) * Number of individual
 (including the paralyzed ones): number of moths released into tunnel *
 Number of paralyzed ones: number of moths found dead at trial end
 (discounted); empty cells indicate zero, no dead moths found * Colony:
 moth cohort ID, from caterpillar collection site * Preselection: results
 of canopy tent release pre-trial procedure (1: light attractive; 0:
 non-light attractive); empty cells are NAs from the first season of
 trials, when no pre-trial procedure was undertaken * Male_when_released:
 number of males released into tunnel, when known; empty cells indicate
 missing data (individuals were sexed for part of the first season of
 trials only) * Female_when_released: number of females released into
 tunnel, when known; empty cells indicate missing data (individuals were
 sexed for part of the first season of trials only) * Note: notes ####
 File: temperatures.csv **Description:** temperatures on trial evenings, in
 Fahrenheit ##### Variables * Date: trial date * temp: average temperature
 at that location on that date, in Fahrenheit * temp_min: minumum
 temperatures at that location on that date, in Fahrenheit #### File:
 all_2024_F-mesh-away_no_dark_stats.csv **Description:**  ##### Variables *
 channel: for guide to ELF imagery processing, see Nilsson and Smolka 2021
 #### File: satellite_data.csv **Description:** light pollution levels at
 varying buffer distances around caterpillar collection sites #####
 Variables * mean: mean light pollution intensity in nW/cm^2/sr * median:
 median light pollution intensity in nW/cm^2/sr * min: minimum light
 pollution intensity in nW/cm^2/sr * max: maximum light pollution intensity
 in nW/cm^2/sr * sd: SD of light pollution intensity in nW/cm^2/sr * n:
 disregard * radius: radius around experiment site in m * state: state
 where experiment took place #### File:
 both_2023_F-mesh-away_no_dark_stats.csv **Description:**  ##### Variables
 * channel: for guide to ELF imagery processing, see Nilsson and Smolka
 2021 #### File: skyglow_2022.png **Description:** light pollution map used
 in Figure 3, from 2022 Light Pollution Atlas, can be found at the
 following link:
 [djlorenz.github.io/astronomy/lp2022](http://djlorenz.github.io/astronomy/lp2022) #### File: VIIRS_2022.tif **Description:** VIIRS-DNB satellite map used in Figure 3. The Google Earth Engine version of the VIIRS annual nighttime lights product (NOAA/VIIRS/DNB/ANNUAL_V21) specifies: “Data ... are not subject to copyright and carry no restrictions on their subsequent use by the public. Once obtained, they may be put to any lawful use.” ## Code/software All statistical analyses were conducted in R (version 4.5.1; RStudio version 2025.05.1+513). Details including a list of packages can be found within the code.Rmd RNotebook.