Effect Of Different Flower Colors Of Oil-Seed Rape On Insect-Pollinators Diversity And Pollination Function

The abundance and diversity of pollinators are critical to ecosystem function and crop productivity,and flower color is one of the main floral characteristics used by pollinators to locate flowers.Different flower colors may affect the diversity of pollinators and thus affect their pollination function.In this paper,we chose pollinators as the research object,based on the agricultural background of large-scale promotion and cultivation of colored oilseed rape,to systematically evaluate the field survey methods of pollinators,analyze the differences in pollinator communities and population dynamics of colored rape attracting pollinators with different flower colors,and the effects of different flower colors on pollination functions of pollinators.1.Comparison of insect-pollinators community captured by pan trap and window trap in oilseed rape fieldWe aimed to test whether window trap could be used in place of pan trap in agricultural fields by comparing the community diversity and species composition of the two methods.A two-year study was conducted in oilseed rape fields to compare the performance of these two sampling methods.The results showed that window trap captured more species and numbers of pollinators and more rare species than pan traps.In terms of community structure,the dominant species captured by the window trap and the pan trap were similar;for the overall species,the pollinators captured by the window trap showed higher similarity and homogeneity compared to the pan trap.Therefore,window trap can be used as an alternative to pan traps as a survey method for pollinator communities in agricultural ecosystems.2.Effect of flower color on pollinator diversity in oilseed rapeIn order to investigate the effect of flower color on pollinating insect diversity,this experiment applied pan traps and window trap to investigate pollinating insect diversity in oilseed rape field with different flower colors for two consecutive years.The results showed that colored oilseed rape had a good attraction to pollinators,and a total of 108 species of pollinators in 4 orders and 34 families were captured in two years.Apis mellifera,Lasioglossum politum and Delia platura were the dominant pollinators in colored oilseed rape fields.The red rape attracted the most Lepidoptera species,the white rape attracted the most Diptera and Hymenoptera species,and the purple rape attracted the least number of pollinator species;the orange rape attracted the highest number of pollinators,and the yellow rape attracted the least number of pollinators.Comparing the α-diversity of insect-pollinators attracted by different flower colors of oilseed rape,it was found that there was no significant difference between different flower colors as a whole,but only in the number of individual insect-pollinators attracted.3.Effect of flower color on the dynamics of insect-pollinators in oilseed rapeThe results of monitoring the population dynamics of insect-pollinators in the field during the flowering period of six colored oilseed rape species in 2021 and 2022 showed that the overall change in the number of pollinating insects in the field had such a process that the number of pollinators in the field was low during the early flowering period of oilseed rape,and with the increase of flowering resources in the field,the number of pollinator populations kept rising and reached the peak at the full flowering period,and when entering the late flowering period,the number of pollinator populations began to decline at the end of the flowering period.The overall trend was to increase first and then decrease.Comparing the pollination dynamics of the major group of pollinators,we found that the peak of individuals of Hymenoptera and Diptera pollinators occurred at the flowering stage,but there were differences in the specific time points.Comparing the population dynamics of pollinators in different flowering rape plots,it was found that the number of individuals of pollinators occurring in different flowering rape field differed significantly in some periods,but the overall population change trend was consistent.4.Effect of flower color on pollination function of insect-pollinators in oilseed rapeThis chapter focuses on the pollination function of pollination insects in color rape field,evaluates the effect of pollination on the yield of color rape and analyzes the effects of different oilseed rape flower colors on the pollination function.The results showed that insect pollination could significantly increase the yield of colored rape.The main branch seed setting rate,main branch fertilization rate and lateral branch fertilization rate of rape pollinated by insects in 2021 were significantly higher than those without insect pollination,and the fresh and dry weight of rape without insect pollination was significantly higher than that of rape pollinated by insects in 2022.It was found that there was no significant difference in yield increase among different flower colors by comparing the differences of pollination services among different flower colors in 2021.Through a systematic comparison of two pollinator sampling methods,this study clarified that window trap are more suitable for pollinator diversity surveys in agricultural ecosystems than pan trap;at the same time,the effects of different flower colors of colored oilseed rape on pollinator diversity,population dynamics and pollination functions were investigated to provide a reference basis for scientific monitoring,dynamic prediction,and conservation and utilization of pollinators.