Search

BACKGROUND: The diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae), is a notorious pest of cruciferous plants. In temperate areas, annual populations of DBM originate from adult migrants. However, the source populations and migration trajectories of immigrants remain unclear. Here, we investigated migration trajectories of DBM in China using genome-wide single nucleotide polymorphisms (SNPs) genotyped using double-digest RAD (ddRAD) sequencing. We first analyzed patterns of spatial and temporal genetic structure among southern source and northern recipient populations, then inferred migration trajectories into northern regions using discriminant analysis of principal components (DAPC), assignment tests, and spatial kinship patterns. RESULTS: Temporal genetic differentiation among populations was low, indicating that sources of recipient populations and migration trajectories are stable. Spatial genetic structure indicated three genetic clusters in the southern source populations. Assignment tests linked northern populations to the Sichuan cluster, and central–eastern populations to the southern and Yunnan clusters, indicating that Sichuan populations are sources of northern immigrants and southern and Yunnan populations are sources of central–eastern populations. First-order (full-sib) and second-order (half-sib) kin pairs were always found within populations, but ∼ 35–40% of third-order (cousin) pairs were found in different populations. Closely related individuals in different populations were found at distances of 900–1500 km in ∼ 35–40% of cases, while some were separated by > 2000 km. CONCLUSION: This study unravels seasonal migration patterns in the DBM. We demonstrate how careful sampling and population genomic analyses can be combined to help understand cryptic migration patterns in insects. [ABSTRACT FROM AUTHOR]

An illustrated key to the genera and subgenera of the Alysiini (Hymenoptera, Braconidae, Alysiinae) from China is presented. Three genera new for China are reported: Adelurola Strand, 1924, Anisocyrta Foerster, 1863, and Pentapleura Foerster, 1863. The total for China is 26 genera of Alysiini and an additional seven subgenera (excluding the nominal subgenera, which are included in the total of genera). The known Chinese species are listed under each genus and the biology is summarised. Separatatus sinicus (Zheng, Chen & Yang, 2012) and Grammospila eurys (Chen & Wu, 1994) are new combinations. Regetus Papp, 1999, and Adelphenaldis Fischer, 2003, are new synonyms of Eusynaldis Zaykov & Fischer, 1982. In addition, Eusynaldis Zaykov & Fischer and Synaldis Foerster, 1863, are treated as subgenera of Aspilota Foerster, 1863, and Dinotrema Foerster, 1863, respectively. An aberrant species of Separatatus Chen & Wu, 1994, S. parallelus sp. n., is described from Yunnan and Hainan. [ABSTRACT FROM AUTHOR]

Large deep lakes in plateau regions provide crucial ecosystem services but are susceptible to eutrophication due to their long water residence time. To date, the water quality of deep lakes has not received as much attention as that of shallow lakes owing to logistical challenges. This study investigated the seasonal variation and vertical distribution of phosphorus and related environmental variables in a large deep lake in the Yunnan Plateau, China (Fuxian Lake). Generally, the concentrations of total phosphorus (TP, R2 = 0.862), total dissolved phosphorus (TDP, R2 = 0.922), and dissolved inorganic phosphorus (DIP, R2 = 0.889) exhibited a linear increase with the greater water depth, whereas the pH and dissolved oxygen (DO) showed decreasing trends. The TP, TDP, and DIP values were 0.012, 0.006, and 0.004 mg/L, respectively, in surface waters (0.5 m depth), and increased to 0.074, 0.065, and 0.062 mg/L, respectively, at 140.0 m depth. The averaged over ordering method demonstrated that DO and air temperature accounted for a higher proportion of the explained variance of TP, TDP, and DIP in the shallow water layer (0.5–20.0 m). In contrast, DO and pH accounted for a higher proportion of the explained variance of TP, TDP, and DIP in deeper water layers (40.0–150.0 m). As a warm monomictic lake, the higher observed phosphorus concentrations in deeper water and sediment potentially pose a risk of future eutrophication in the Fuxian Lake. Our findings demonstrate that more efficient technical and management measures should be taken to reduce the external phosphorus load to Fuxian Lake, so that the load to and from the sediment will decrease eventually. [Display omitted] • Vertical distribution of P and related variables was examined in a large deep lake. • Water P concentration exhibited a linear increase with the greater water depth. • Phosphorus was affected primarily by DO and air temperature in the shallow water. • Phosphorus was predominantly affected by DO and pH in the deeper water. • Higher concentrations of phosphorus in deeper water pose a risk of eutrophication. [ABSTRACT FROM AUTHOR]