# Shedding light on dark taxa: exploring a cryptic diversity of parasitoid wasps affected by artificial light at night

## TL;DR

This study explores how shielded LED road lights reduce the negative effects of artificial light on parasitoid wasps, revealing new species and their ecological roles.

## Contribution

The study identifies new parasitoid wasp species in Southern Germany and demonstrates the effectiveness of shielded LED lights in mitigating ALAN impacts.

## Key findings

- Shielded LED road lights reduce attraction of nocturnal parasitoid wasps to artificial light.
- 21 species of parasitoid wasps were identified, including 11 new to Southern Germany.
- ALAN impacts may affect pollination and biological control through parasitoid-moth interactions.

## Abstract

Artificial light at night (ALAN) contributes to the globally observed insect decline. ALAN attracts nocturnal insects from their native ecosystems and disturbs their functions in the food web. Road lights in this context are ubiquitous and relevant ALAN sources that are often not considered in conservation approaches. In a previous study we showed that shielded LED road lights are suited to be part of conservation measures by effectively reducing the attraction of nocturnal insects. Here we show that this positive effect holds true for parasitoid wasps in an experimental BACI design (Before-After-Control-Impact). Combining morphological with molecular and phylogenetic analyses, we identified 106 individuals (62 morphotypes) of a minimum of 45 genera out of 13 Hymenoptera families. We were able to identify 21 species, 11 of which are newly reported in Southern Germany (Baden-Württemberg). Further combining knowledge on life history and host appearance from our data and the literature, we discuss potential impacts of ALAN ranging from an influence on nocturnal pollination via parasitoid pressure on moth species and biological control of invasive pest species to tritrophic interactions between primary and secondary parasitoids. We conclusively think that shielded LED road lights will reduce the ecological impact of ALAN on parasitoid wasps in a large and undescribed number of taxa with different host associations, likely affecting associated ecosystem functions such as biological control.

The online version contains supplementary material available at 10.1038/s41598-025-88111-3.