Hao Yu

The family Leuctridae is a species-rich group of Holarctic stoneflies whose phylogenetic relationships, diversification timeline, and biogeographic history remain poorly resolved. We assembled a mitochondrial dataset comprising 30 species representing nine of the twelve currently recognized genera, combining complete and nearly complete mitogenomes with mitochondrial genes extracted from transcriptomes, and nine outgroups, to reconstruct the phylogeny, divergence times, and ancestral ranges of the family. Analyses strongly supported the monophyly of Leuctridae and recovered Megaleuctra as the earliest-diverging lineage, followed by two major Leuctrinae clades: (Despaxia + Leuctra) + Moselia and (Paraleuctra + Pomoleuctra) + (Perlomyia + Rhopalopsole + Zealeuctra). Molecular dating placed the crown origin of the family in the Late Triassic at 205.9 Ma (95% HPD: 178.1–237.0 Ma), with extant genera diversifying from the Late Cretaceous to the Late Eocene. Ancestral-range reconstruction under the DIVALIKE + J model favors western North America as the ancestral area at the crown node (relative probability 0.59) and at most deep nodes, although with substantial uncertainty. The present disjunct distributions between East Asia and North America are most consistent with deep-time range persistence and repeated founder-event colonization, possibly combined with ancient vicariance. Our results provide a novel mitogenome-based framework for further studies of leuctrid diversification.

Plant patches are a common feature of dryland ecosystems, but how within-patch spatial position is associated with plant functional traits–and whether these patterns differ among organs—remains poorly understood. We sampled twigs, leaves, and flowers of the C₄ desert plant Salsola collina from the centers and edges of natural patches in arid Xinjiang, China, using five plots with three patches per plot. For each organ, we measured the concentrations of carbon (C), nitrogen (N), phosphorus (P), sucrose (SUC), fructose (FRU), total soluble sugars (SS), and starch (ST), and calculated non-structural carbohydrate (NSC) concentrations as the sum of SS and ST. Treating the plot as the experimental unit and accounting for paired center–edge observations within plots, we evaluated the effects of patch position, organ type, and their interaction using two-way ANOVA and distance-based multivariate analyses. Organ type accounted for the largest proportion of multivariate trait variation (R² = 0.90), whereas patch position and the Patch × Organ interaction each explained approximately 4% (all p < 0.001). Significant Patch × Organ interactions were detected for 14 of 17 traits, indicating that center–edge differences varied among organs for most traits. N concentrations were higher at patch edges in all three organs, whereas P concentrations were higher in twigs and flowers only; C showed no significant center–edge differences. NSC concentrations were higher at patch edges in all three organs, while SS was higher in edge twigs and leaves and ST was higher in edge flowers. These patterns were accompanied by contrasting organ-specific differences in carbohydrate composition and elemental stoichiometry. Because environmental variables were not measured concurrently, the observed patterns should be interpreted as spatial associations rather than demonstrated environmental mechanisms. These findings indicate that organ identity and within-patch position are jointly associated with variation in the carbon-, nutrient-, and carbohydrate-related traits of S. collina, highlighting the importance of considering organ-specific variation when evaluating fine-scale spatial heterogeneity in dryland plants.

Biological soil crusts (BSCs) are important components of dryland ecosystems, yet nutrient patterns in adjacent uncovered soils remain unclear. We surveyed 70 sites across the Gurbantunggut Desert and collected 209 composite samples from the adjacent 0–5 cm surface-soil layer, categorized into three groups: uncrusted bare sand (n = 32), soil adjacent to algal–lichen crusts (n = 48), and soil adjacent to moss crusts (n = 129), with bare sand serving as the uncrusted reference category. The results showed that: (1) total nitrogen differed among the three BSC-associated soil categories (p = 0.041), whereas soil organic carbon, total phosphorus, and total potassium did not (all p > 0.05); (2) NO₃⁻-N, NH₄⁺-N, extractable inorganic N, NaHCO₃-extractable phosphorus, and NH₄OAc-extractable potassium differed significantly among categories (all p < 0.001) and were generally highest in soil adjacent to moss crusts; and (3) random forest models explained approximately 38–65% of nutrient variation and identified EC, total nitrogen, and the site-level BSC metric as the leading predictors. The final piecewise structural equation model explained 35.3–76% of nutrient variation. These findings indicate marked regional heterogeneity in extractable nutrient fractions associated with different BSC types.

Henosepilachna vigintioctopunctata is a major pest of solanaceous crops. Matrix metalloproteinase 2 (MMP2) is a zinc ion-dependent endopeptidase that plays a crucial role in the remodeling process of the extracellular matrix (ECM) within cells. However, the function of HvMMP2 in H. vigintioctopunctata remains unknown. In this study, we cloned and characterized the HvMMP2 gene in H. vigintioctopunctata and investigated its function using RNA interference (RNAi). HvMMP2 exists as two transcript variants that differ at the 5′ end. HvMMP2 is highly expressed in the prepupal stage, the pupal stage and the intestine. Silencing HvMMP2 expression in fourth-instar larvae led to approximately 54% mortality at the prepupal stage, with the remaining larvae dying after pupation. RNAi with HvMMP2 in third-instar larvae did not affect their development to the fourth instar, but caused mortality in the majority of larvae during the prepupal and pupal stages, and most of these pupae exhibited wing deformities. Examination of these stunted larvae by dissection showed that their fat bodies were abnormally shaped and that yellow uric acid crystals had accumulated in the Malpighian tubules. Collectively, our findings indicate that HvMMP2 plays a critical role in pupation and eclosion in H. vigintioctopunctata and support HvMMP2 as a potential molecular target for further RNAi-based control studies.