Insect herbivores often exhibit host preference and feeding differentiation underpinning fine-scale niche partitioning, yet their linkage to larval performance remains poorly understood. On the Qinghai–Tibet Plateau, two sympatric leaf beetles, Chrysomela vigintipunctata alticola (CV) and Phratora vitellinae (PV) (both Coleoptera: Chrysomelidae), co-occur on two willow species occupying distinct microhabitats: CV predominantly uses abundant Salix atopantha (SW), while PV specializes on rare Salix wangiana var. tibetica (LW) (both Malpighiales: Salicaceae). To disentangle intrinsic feeding response from natal-host induction, we combined dual-choice feeding bioassays with controlled natal-host rearing experiments using first-instar larvae originating from both hosts, and evaluated fitness consequences in terms of morphology and instar duration. PV larvae exhibited a consistent preference for LW, coupled with wider head capsules. In contrast, CV larvae showed no intrinsic preference; specifically, those from SW remained non-selective, while those from LW developed a delayed preference. CV larvae developed faster on nitrogen-rich SW, whereas LW contained higher salicylate esters. These results indicate that PV prioritizes growth and chemical defensive sequestration on LW, whereas CV prioritizes rapid development by utilizing the nutrient-rich SW. Our results reveal distinct resource-use patterns and life-history strategies that facilitate local co-occurrence of the two leaf beetles within the alpine meadow ecosystem.

Although silvopastoral systems are widely recognized to improve ecosystem services, empirical evidence regarding their long-term effects on herbaceous diversity during succession remains scarce. In 2011, we established a silvopastoral experiment in the low hilly area of western Henan Province, China. Four pure forest plots—poplar (Populus simonii, PS), oriental thuja (Platycladus orientalis, PO), Chinese cork oak (Quercus variabilis, QV) and black locust (Robinia pseudoacacia, RP)—were planted on natural wasteland, with perennial alfalfa (Medicago sativa, MS) intercropped to form silvopastoral systems (PS-MS, PO-MS, QV-MS, RP-MS), with a natural wasteland plot serving as the control (CK). In July 2024, we investigated the species density, richness, and aboveground biomass of herbaceous communities across all plots. Species composition differed significantly between MS and CK, PS-MS and PS, and PO-MS and PO. Silvopastoral systems and MS generally exhibited higher density, richness, and biomass than pure forests and CK. Furthermore, MS and silvopastoral systems showed uniform density and biomass across slope positions, whereas CK and pure forests had higher values downslope, along with shifts in relative biomass. Except for MS and PS-MS, all plots had higher species richness downslope. Soil nutrient properties were closely correlated with the biomass, richness, density, and functional groups. These findings indicate that silvopastoral systems can significantly increase herbaceous density, richness, and biomass and alter species composition, with the effects varying by the dominant tree species.

In plant–pre-dispersal seed predator interactions (e.g., flowerheads–flies), insect morphological differentiation is frequently driven by divergent host plants. However, wing morphological variation among flies associated with different flowerhead species has seldom been explored in natural alpine systems. In an alpine meadow of the Qinghai–Tibet Plateau, larvae of four host-associated morphological groups of Tephritis sp. cf. femoralis (1, 2, 3, 4) feed on four asteraceous species: Saussurea nigrescens (SN), Carduus nutans (CN), Leontopodium leontopodioides (LL), and Anaphalis lactea (AL). We examined the wing size and shape of these four groups using a landmark-based geometric morphometric approach. The host plants vary significantly in capitular diameter, dry weight, and depth. Within each host-associated group, female wing sizes (length, width and centroid size) were significantly larger than those of males. Wing size differed significantly among the four female and four male groups across host plants. Female ovipositor length varied in parallel with capitulum depth across the four host plants. Significant intersexual differences in wing shape were observed in SN, LL, and AL. Wing shape also varied distinctly among groups in both sexes across host plant capitula, enabling clear discrimination of host-associated groups. Linear discriminant analysis achieved high correct classification rates for both sexes, supporting clear morphological separation among host-associated groups. In conclusion, variations in wing size, wing shape and ovipositor length were associated with host traits. Overall, our study illustrates morphological differentiation correlated with host plants in flowerhead–fly pre-dispersal seed predator interactions in the alpine meadow system.