Global meta-analysis of urbanization stressors on insect abundance, richness, and traits

Anthropic stressors are among the greatest concerns in nature conservation. Among these, deforestation and urban expansion are major drivers of habitat loss, which is a major threat to biodiversity. Insects, the largest and most abundant group of animals, are declining at alarming rates. However, global estimates of the impact of anthropic stressors on insect abundance, richness, and traits are still lacking. Here, we performed a meta-analysis to estimate the impact of urbanization stressors on insect abundance, diversity, and traits. Our design focused on the effects of urbanization on moderators such as insects' activity periods, climatic zones, development stages, ecosystem, functional roles, mobility, orders, and life history. We found that insects are negatively affected by urban stressors across most moderators evaluated. Our research estimated that in insects, urbanization resulted in a mean decrease of 42 % in abundance, 40 % in richness, and 24 % in trait effects, compared to a conserved area. Even though in general there was greater loss in abundance than in richness, each moderator was affected by different means and to varying degrees, which results from artificial lighting at night as well as land use. Our study highlights the importance of promoting better protection of insect biodiversity in the future from the enormous loss in biodiversity reported in >500 papers assessed.