The data was collected from 88 plots of BEF-China for five years (2015, 2016, 2018, 2019, 2020) using trap nests. Specifically, we collected trap nests monthly to sample solitary bees and wasps in the 88 plots from September to November in 2015 and April to November in 2016, 2018, 2019 and 2020. For each plot, we installed two poles with trap nests (11 m apart from each other and 9 m away from the nearest adjacent plots) along a SW–NE diagonal . Each pole stood 1.5 m above ground, and each trap nest consisted of two PVC tubes (length: 22 cm × diameter: 12.5 cm) filled with 75 ± 9 (SD) reed internodes of 20 cm length and diameters varying between 0.1 and 2.0 cm. Every month, we sampled the reeds with nesting hymenopterans and replaced them with internodes of the same diameter. All the samples were reared in glass test tubes under ambient conditions until specimens hatched. The hatched hosts and parasitoids to species or morphospecies based on reference specimens were identified (vouchered at the Institute of Zoology, CAS, Beijing). For the data, we did not distinguish between the two life-history strategies of parasitoids (true parasitoids and kleptoparasitoids, including hymenopteran and dipteran parasitoids) because they both have the same ecological result, death of host brood cells.

88 plots (including VIP plots) for both study sites.

September to November in 2015 and April to November in 2016, 2018, 2019 and 2020.

Hymenoptera and few Diptera.