The influence of urban light pollution on nocturnal insect activity patterns

Thesis Abstract

Urban light pollution has emerged as a pervasive environmental issue, significantly altering natural nocturnal ecosystems and potentially disrupting the behavioral patterns of nocturnal insects, which are vital for ecosystem functioning, pollination, and food webs. Despite increasing awareness of light pollution's ecological impacts, comprehensive empirical data on its specific influence on nocturnal insect activity remains limited. This study aims to systematically evaluate the influence of urban light pollution on nocturnal insect activity patterns, with specific objectives to quantify insect activity levels across different urban luminance zones, assess shifts in activity timing and diversity, and identify potential correlations between light intensity and insect behavioral responses. The research employs a comparative field study design conducted across three urban zones characterized by varying degrees of artificial light intensity high, moderate, and low light pollution areas within the metropolitan region. The target population comprises nocturnal insects observed through standardized trapping methods over a six-month period, spanning both dry and rainy seasons. A total of 150 traps (50 per zone) will be deployed, utilizing UV light traps supplemented with motion-activated cameras to record insect activity. Data collection instruments include light meters for quantifying ambient light levels, insect traps for capturing activity patterns, and photographic equipment for behavioral documentation. The validity and reliability of data collection instruments will be ensured through calibration of light meters prior to deployment and standardized trap placement protocols. The collected data will be subjected to quantitative analysis using statistical techniques such as ANOVA to compare insect abundance and diversity across zones, regression analysis to evaluate the relationship between light intensity and insect activity metrics, and multivariate analyses (e.g., Non-metric Multidimensional Scaling - NMDS) to explore community compositional shifts. Thematic analysis will be employed for qualitative behavioral observations captured via cameras. The study will be framed within the theoretical context of the Visual Foraging and Sensory Disruption Theories, which posit that artificial lighting can interfere with insects’ orientation and foraging behavior, and the Ecological Light Pollution Model, emphasizing the ecological consequences of artificial light on wildlife. Expected findings include significant reductions in insect abundance and diversity in zones with higher light pollution, shifts in peak activity times towards later hours, and alterations in community composition, with some taxa exhibiting behavioral avoidance to brightly lit areas. The study anticipates establishing a quantitative correlation between light intensity and disruption in insect activity patterns, supporting the hypothesis that urban light pollution exerts a measurable and adverse influence on nocturnal insects. The research contributes to ecological knowledge by providing empirical evidence of the behavioral impacts of light pollution on nocturnal insects, which are often overlooked in urban biodiversity assessments. It offers critical insights for urban planning and conservation strategies aimed at mitigating light pollution through targeted lighting designs and policies. The main conclusion infers that artificial light at night significantly alters insect activity and community structure, underscoring the need for light management practices that balance urban development with ecological preservation. Based on the findings, the study recommends implementing "dark sky" lighting policies, promoting the use of insect-friendly lighting technologies, and establishing ecological corridors to support nocturnal insect populations. Future research should explore long-term population dynamics and the cascading effects of insect behavioral changes on higher trophic levels, thereby fostering a holistic approach to urban ecological sustainability.