Moth traps shine a light on nocturnal parasitoid wasps: Snapshot assessment of UK diversity and distributions

Abstract Biodiversity monitoring is essential to understand anthropogenic impacts on ecological communities. However, species‐rich groups such as parasitoid wasps (Hymenoptera) remain poorly documented despite their importance as ecosystem regulators. We require improved monitoring approaches for such neglected taxa. Capitalising on nocturnal parasitoid wasps' attraction to light traps used by moth trappers, we aimed to determine the efficiency of this method to generate information on the diversity and distributions of nocturnal parasitoids in the United Kingdom. We enlisted 130 moth‐trappers from across the United Kingdom to sample the parasitoid ‘bycatch’ from their traps between May–September. This resulted in over 6700 specimens belonging to over 184 taxa collected over 6141 nights, generating a near‐complete national species inventory of our focal genera, Netelia (19/24 expected species), Ophion (31/35), Enicospilus (8/9), Perilissus (6/8), Eremotylus (2/2) and Stauropoctonus (1/1), equalling nearly half (46.8%) of all known Great Britain records for these genera. We assessed the quality of our data based on historical records. Our analyses suggest that 5 months of sampling in this way can produce species distribution models comparable to multiple decades of historical data, as well as information on life‐history traits such as phenology. Such information is vital for conservation. Overall, this study illustrates how high‐quality national‐level data on understudied insects can be obtained rapidly using existing infrastructure, and highlights the value of amateur naturalists in monitoring neglected taxa. We provide recommendations for future studies on such taxa and discuss sampling effort and biases.