DNA barcoding resolves quantitative multi‐trophic interaction networks and reveals pest species in trap nests

Abstract

Insects, as one of the most species‐rich taxa with enormous taxonomic, behavioural and functional diversity, are in decline. Bees and wasps are especially crucial for ecosystems as pollinators or to control populations of other insects. To understand population drivers, comprehensive knowledge about top‐down and bottom‐up interactions, including all interaction partners, is needed. Nests of trap‐nesting bees and wasps include multi‐trophic interactions between bees, wasps, their food resources and natural enemies, simultaneously, however, up to today, all trophic interactions are not yet included in trap nest research because of challenges to identify the food used by nesting bees and wasps. Here, we reconstructed quantitative three‐ and four‐trophic interaction networks of species in three apoid wasp families using DNA barcoding. The obtained tripartite and quadripartite networks encompassed natural enemy‐wasp‐spider and natural enemy‐wasp‐herbivore‐plant interactions. Moreover, we identified so far undescribed Hymenoptera‐prey interactions, including prey species known as agricultural and forest pests. More extensive research on bee and wasp multitrophic interaction networks will provide valuable insights to better understand responses to environmental and biodiversity change, to investigate ecological theory and to reveal so far unknown feeding links.

Microhymenoptera in roadside verges and the potential of arthropod‐friendly mowing for their preservation

“…In homogenous landscapes dominated by monocultures, insects suffer from the absence of nesting places and host plants, disconnected habitats (Harrison & Bruna, 1999) and intensive use of pesticides (Brühl et al., 2021; Sanchez‐Bayo, 2011). In grasslands, insects are negatively affected by the deposition of nutrients due to airborne nitrogen (Peppler‐Lisbach et al., 2020), the overuse of fertilizers (Niedrist et al., 2009), mulching (Moog et al., 2002) and frequent mowing (Niedrist et al., 2009) which reduce the diversity of wild plant species, that are essential food sources for insects (Fornoff et al., 2023). As a consequence, the number of specialist species decline and species composition becomes more homogenous (Gossner et al., 2016).…”

“…It is one of the most species‐rich insect order in the world (Forbes et al., 2018), comprising ants, bees, sawflies and wasps (Peters et al., 2017). While their importance for pollination is well‐known to the public (Klein et al., 2007; Potts et al., 2016), their function as natural control agents for pest species is rarely mentioned in the public discussion (but see Fornoff et al., 2023). Most Hymenoptera are small‐sized parasitoids and develop in or on certain host species, mostly herbivorous insects, thereby providing natural control of their hosts and contributing to the natural balance and the resilience of our ecosystems (LaSalle, 1993; LaSalle & Gauld, 1991).…”