Invasive oaks escape pre-dispersal insect seed predation and trap enemies in their seeds

Species introduced to habitats outside their native range often escape control by their natural enemies.Besides competing with native species,an alien species might also affect the native herbivores by introducing a new source of different quality food.Here,we describe the case of northern red oak(Quercus rubra)invasion in Europe.We collected data on insect(moth Cydia spp.and weevil Curculio spp.)seed predation of northern red oak in its native(USA,North America)and invasive(Poland,Europe)range,as well as for sessile oaks(Quercus petrea)in Europe.We also evaluated the quality of acorns as hosts for weevil larvae by collecting infested acorns and measuring weevil developmental success,and quantifying acorn traits such as seed mass,tannins,lipids and protein concentration.We used DNA barcoding to identify insects to the species level.The predation by moths was similar and very low in both species and in both ranges.However,red oaks escape pre-dispersal seed predation by weevils in Europe.Weevil infestation rates of northern red oak acorns in their invasive range were 10 times lower than that of sessile oaks,and also 10 times lower than that of red oaks in North America.Furthermore,even when weevils oviposited into northern red oaks,the larvae failed to develop,suggesting that the exotic host created a trap for the insect.This phenomenon might gradually decrease the local abundance of the seed predator,and further aid the invasion.

Social-ecological transformations of Inner Mongolia:a sustainability perspective

Introduction:Sustainability requires the reconciling of human needs with the healthy natural ecosystem,which should be achieved within the grand course of industrialization and modernization.Systematic transitions on demography,economy,technology,and institutions are required,while different civilizations may take their respective paths.In this study,we analyze the social-ecological transitions of Inner Mongolia Autonomous Region of China during the past century,focusing on major changes in its environmental,demographic,and socioeconomic conditions.Results:A two-level social-ecological system analysis framework was proposed,and four stages of transition were identified:traditional nomadism,primitive industrial civilization,collectivization era,and economic reform/opendoor policy era.Our analysis showed that Inner Mongolia has made great achievements in its socioeconomic domains but is faced with numerous challenging environmental problems.Overconsumption of resources and failure to curtail ecological degradation may lead to a trap of unsustainability.Conclusions:However,the slowing-down population growth,improvements of the economic structure,and many new sustainability initiatives and strong support from the central government together give hope for a sustainable future of the region.