The Geographical Variation Of Pollination Networks Of Invasive Plants Solidago Canadensis And Bidens Frondosa

To explore the geographical variations in pollination network of invasive plants Solidago canadensis and Bidens frondosa,the study was conducted during September to November in 2017 and 2018 in Anhui,Beijing,Fujian,Hubei,Jiangxi,Shandong and Zhejiang provinces.We selected 15 sampling sites to carry out the experiment,and took S.canadensis,B.frondosa and its surrounding flowering plants as the research object.The two species of invasive compositae plants pollinator insects and their pollination network were investigated,and the differences of pollination networks between different regions were analyzed by combining environmental factors.The results indicated that:(1)As the generalized pollinator species,S.canadensis and B.frondosa have a large number of pollination insects.The main flower-visiting insects of S.canadensis are hymenoptera diptera and lepidoptera,and the insects vary in different areas.In high latitudes and low latitudes,flower-visiting insects are mainly flies,while flower-visiting insects of family Apidae accounted for a large proportion in mid-latitude;Diptera and hymenoptera predominate in the pollinators of B.frondosa,and insect species richness are lower at higher latitudes than that in lower latitudes.(2)After the successful invasion of the Compositae,it competes with pollinators of native plants and dominates the local pollination network.When S.canadensis and B.frondosa are integrated into the local network as dominant species,both showed a high nesting degree and asymmetries,which are shown in number and intenstity in pollination network connection.(3)The pollination networks are different in different regions.In pollination network structure,the nestedness of pollination network may increase with the length of intrusion time.In the characteristics of pollination network,the pollination networks of S.canadensis and B.frondosa tended to generalize from south to north.With the increase of latitude and longitude,the pollination network tend to be generalized,while with the increase of temperature and rainfall,the pollination network tend to be specialized.The pollination network sizes decrease with the increase of latitude and longitude and increase with the increase of temperature and rainfall.Besides,the interactions of S.canadensis pollination network decrease with the increase of longitude,temperature,rainfall and increase with the increase of latitude,while the interaction number of B.frondosa pollination network decrease with the increase of latitude and increased with the increase of temperature and rainfall.