Diversity Of Flower Visiting Beetles And Their Interaction With Environments On The Yulong Snow Mountains

Beetles are one of the most important pollinators,and their species diversity ranks second in pollinating animals after the Lepidoptera.Angiosperm flowers are one of the important microhabitats promoting beetle diversity,however,flower visiting beetles diversity are not fully exploited.Previous studies on the flower visiting beetles have focused on the tropics and little is known about the diversity of these beetles in the environments at high elevation in the mountain regions.There were only a few studies on flower visiting beetles in China,and no research has been done on the variation of flower visiting beetles diversity along elevation gredient with different vegetation and habitats.Additionally,we do not know how divergent habitats influence the distribution of beetles among montane flora.This research on flower visiting beetles will help to further uncover the diversity of pollinator beetles in wild plant resources.It also provides scientific basis for pollination biology research and pest control for crops and wild plants.We sampled flower visiting beetles systematically in angiosperm flowers at 12 sites at two elevations（the low elevation:2700 m and the high elevation:3200 m）and in two habitats（meadow and forest）for two consecutive years（2018 and 2019）on the Yulong Snow Mountains in Yunnan,southwestern China.We collected and identified the flower visiting beetles,and recorded the flowering plants these beetles collected.The diversity of flower visiting beetles and the influence of elevations and divergent habitats on beetle diversity were analyzed using R.The structure of plant-flower visiting beetles networks,the variation of networks among sites,and the influences of networks by elevations and divergent habitats were analyzed using the package bipartite in R.The research results as follow:（1）Our study showed a high species diversity of flower visiting beetles at subalpine envrioments of Yulong Snow Mountains.We collected 3391 specimens belonging to 153 morpho-species of beetles from 90 plant species.The highest species richness was the Chrysomelidae accounting 27.45%（42morph-species）,followed by the Nitidulidae 22.22%（34 morph-species）.The highest abundance of flower visiting beetles specimens was the Nitidulidae made up 48.86%（1657 specimens）,followed by the Chrysomelidae 28.16%（955 specimens）.There were three dominant species,they were Nonarthra variabilis Baly（Chrysomelidae）,Lamiogethes sp.1 and Epuraeinae sp.1（Nitidulidae）.（2）The morpho-species,families and specimens of flower visiting beetles in the low elevation sites were higher than they were in the high elevation sites.The morpho-species or specimens belonging to the Nitidulidae and Chrysomelidae were the dominant both in the low and high elevations.At both the high and low elevations,the species of the families Nitidulidae and Chrysomelidae was more than 45%of the total species of flower visiting beetles;the individuals of these two families were more than 70%of the total number of individual specimens.The species diversity and abundance of flower visiting beetles in the forest were higher than in the meadow.The dominant families of species diversity or abundance were the Chrysomelidae and Nitidulidae both in forest and meadow habitats.Both forest and meadow transects,the species of families Nitidulidae and Chrysomelidae was more than 40%of the total species of flower visiting beetles;the individuals of these two families were more than 45%of the total number of individuals.The species variation trend between flower visiting beetles and flowering plants were roughly the same or beetles slightly behind plants.（3）All three diversity index the Shannon index,the Simpson index and the J index showed no significant difference among transects regardless of elevations and habitats.However,the diversity of the low elevation transects was generally higher than the high elevation transects,the diversity of the high elevation forest transects was generally higher than the high elevation meadow transects.（4）Flower visiting beetles had a preference for flowering plants in some families.The Asteraceae,Ericaceae,Rosaceae,Apiaceae and Ranunculaceae were the dominant families visiting by beetles.The common feature of these families owes large flowers and/or inflorescences including capitulums and corymbs.（5）The total network showed strong modularity（Q=0.632）with a Z-score of 138.29.There were13 modules detected from the total network.The total network also showed a nested structure.The NODF was 11.9651 with a Z-score of-22.38,which was significantly different from the null model（p=0）.The network size at the low elevation was higher than that at the high elevation（F=8.329,p=0.02）.The number of interactions were also slightly higher at the low elevation（F=5.472,p=0.047）,but no habitat difference was shown（F=4.704,p=0.062）.The interaction effects between elevation and habitat were also significant for the number of interactions（F=9.991,p=0.013）.The number of beetle species did not show significant differences between elevations and between habitat types（p>0.05）.The numbers of plant species with flowers and/or inflorescences inhabited by beetles were lower at the high elevation sites compared with the low elevation sites（F=36.698,p<0.001）.One beetle species Galerucinae sp.5 of the family Chrysomelidae was detected as the network hub.Six additional beetle species were module hubs,they were Lamiogethes sp.1 of the Nitidulidae,Epuraeinae sp.1 of the Nitidulidae,Nonarthra variabilis of the Chrysomelidae,Bruchidius lautus（Sharp）of the Crioceridae,Epuraeinae sp.5 of the Nitidulidae and Mordellidae sp.1.Six species were detected as connectors,they were Galerucinae sp.1,Epuraeinae sp.2,Popillia cribricollis Ohaus,Brassicogethes affinis,Lamiogethes pseudoviridiangustus,Coccinella septemunctata Linnaeus.For plants,no network hub was detected.Ligularia alatipes Hand.-Mazz.（Asteraceae）was module hub,Halenia elliptica D.Don（Gentianaceae）and Thalictrum javanicum Bl.（Ranunculaceae）were detected as connectors.For the network structures,we detected a significant effect of elevation on weighted connectance,H₂’,niche overlap of beetles,and functional complementarity of beetles.The specialization of interacting（H₂’）was higher at the low elevation（F=7.191,p<0.05）,and there was also a significant interacting effect for elevations and habitat types（p<0.05）,but no difference among habitat types.Niche overlap of beetle species showed differences among both elevations（F=100.330,p<0.001）and habitat types（F=34.279,p<0.001）,this probably dued to the beetles’preference for habitats and flowering plants.The interaction of flower visiting beetles and plants showed significantly different among sites.The dissimilarity of interactions among sites was determined by species composition turnover.The dissimilarity of species composition（β_S）among different sites were high in general,the average was0.82（0.339–0.995）.Consequently,dissimilarity of interactions established between species common to sites(β_OS)was extremely low due to the lower levels of species sharing.Network turnover among sites was determined by species composition turnover.Network turnover between elevations was always higher than within elevation（among habitats）.In all,this study revealed a high species diversity of flower visiting beetles in plants at high elevation areas.Elevations and habitats had effect on the plant-flower visiting beetles interaction network,and the species diversity of flower visiting beetles at the low elevation was higher than that at the high elevation.By analysising the network structure of plant-flower visiting beetles,we found that the interaction network showed strong mudularity and specialization,which may be due to the selectivity of flower visiting beetles to habitat and preference for flowering plants.The variation of plant-flower visiting beetles interaction network was mainly determined by the species turnover.The results highlight that a high diversity of flower visiting beetles in subalpine conifer forest of Yulong Snow Mountains,such diversity is comparable to flower visiting beetle diversity in tropics.Uncovering of beetle diversity in this study add more potential pollinator resources.The impact of flower visiting beetles on pollination and reproduction of flowering plants and their roles in ecosystems warrant further evaluation.