The structure of Lepidoptera-plant interaction networks across clades, life stages, and environmental gradients

Aim Integrate biogeographic and ecological knowledge to understand the spatial-structural patterns of plant-insect interaction networks at the landscape scale. Location The 36,000 km 2 German state of Baden-Württemberg, Central Europe. Methods We integrated extensive data of Lepidoptera-plant occurrences and interactions to inferentially construct local interaction networks across Baden-Württemberg, considering in total 3148 plant and 980 Lepidoptera species, covering butterflies, Noctuid moths, Geometrid moths and Bombycoid moths. We quantified clade- and life-stage-specific network structures and related these features to GIS-informed environmental conditions, thereby revealing the spatial (environmental) patterns and potential drivers of networks’ structural variation across the landscape. Results Spanning the same environmental gradients, Lepidoptera clades and life stages can form various interaction structures with food plants and exhibit distinct spatial-structural patterns. For all major Lepidopteran groups, except Geometrid moths, potential diet across life stages tended to broaden toward low-elevation farmlands. The larval and adult networks of butterflies became less modular with farmland coverage; the same for adult Noctuid moths, but the inverse for adult Geometrid moths. With increasing elevation, the larval and adult networks of Noctuid moths became less and more modular, respectively, whereas Geometrid adult networks became more modular. While the adult dietary niche of butterflies was more overlapped at low elevation, those of Noctuid and Geometrid moths further associated with land cover and were more overlapped toward low- and high-elevation farmlands, respectively. Main conclusions Environmental factors and biotic interactions together shape ecological communities. By particularly accounting for species-interaction contexts, we revealed the spatial-structural patterns of Lepidoptera-plant networks along geo-climate and land-cover gradients, where the shaping mechanisms likely include both evolutionary (e.g., resource-consumer co-evolution) and ecological (e.g., competitive exclusion) processes and are specific to Lepidoptera’s clade or life stage. Such biogeographical structural patterns provide ecological and conservation implications at both species and community levels, and can indicate the potential response of Lepidoptera-plant communities to environmental changes.