The Study On The Biodiversity Of Flower-Visiting Spider And Flower-Visiting Preference Of Ebrechtella Tricuspidata

Many arthropods exhibit flower-visiting behavior,including a variety of spider species in the nature.However,as spiders are assumed to be strictly predatory,flower-visiting spiders are an often neglected group.Moreover,the researches about flower-visiting spiders are not very comprehensive,especially in China is blank.To the best of our knowledge,this study is the first to propose the term “flower-visiting spiders” and conduct a systematic investigation of their diversity.As such,they require specific flowers or substrates for hunting,which are most often selected using sensory cues(e.g.,vision and olfactory).However,few studies have examined the sensory preference of spiders for particular flowers.Here,we investigated the choice preferences of the crab spider Ebrechtella tricuspidata for different inflorescence characteristics(color,shape,and scent).1.Biodiversity survey of flower-visiting spiders:We conducted a systematic biodiversity study of flower-visiting spiders based on published papers and field surveys.Most previous studies have focused on the herbivorous behavior of flower-visiting spiders(nectivory or pollinivory)and their effects on host flowers(tritrophic interactions with flower-visiting insects).In the two-years field survey,we utilized standard transect walks(active sampling)and color pan traps(passive sampling)to investigate species occurrence,diurnal and seasonal variation,and flower color preference of flower-visiting spiders.From the transect walks,319 spiders,including 33 species from 13 families,were found on inflorescences in the study area.The number of spiders in each family followed the order: Thomisidae(78%),Tetragnathidae(3.7%),Araneidae(3.4%),Gnaphosidae(3.4%),Salticidae(3.4%),Lycosidae(3.1%),Oxyopidae(1.6%),Pisauridae(0.94%),Clubionidae(0.62%),Linyphiidae(0.62%),Philodromidae(0.31%),Theridiidae(0.31%),and Titanoecidae(0.31%).In terms of plant species,tulip flowers had the largest number and species of spiders.The number of flower-visiting juvenile spiders was significantly higher than that of flower-visiting adult spiders.Furthermore,the number of flower-visiting spiders was significantly higher in spring than in autumn,with a significantly higher number in the afternoon than in the morning.In regard to number of spiders,host inflorescences followed the order red,white,yellow,pink,and purple;the number of spiders on red and white inflorescences was significantly higher than that on the yellow,pink,and purple inflorescences.Based on the above transect results,the species diversity Shannon Wiener index was 1.236,Pielou index(evenness index)was 0.353,and Margalef index was 5.551.For the pan traps,a total of 228 pans(57 clusters)were collected.We collected a total of 186 spiders belonging to eight families,with Lycosidae dominant.The collected spiders included 70 juveniles,71 adult males,and 45 adult females.The number of juvenile and male spiders was significantly higher than that of female spiders.We collected 45,47,56,and 38 individuals in the green,white,red,and yellow pans,respectively.Compared to the number of adult females,a significantly greater number of juvenile and male spiders were collected in the red pans,though no significant differences were found for the other three colors.Overall,the four colored pans did not differ significantly in the number of spiders collected,and there were no significant differences among the pairwise comparisons.Based on the above pan trap results,the species diversity Shannon Wiener index was 1.200,Pielou index was0.577,and Margalef index was 1.340.2.Visual preference of Ebrechtella tricuspidata for host flowers:In the visual preference experiments,results showed that adult spiders explored all colors and shapes,whereas juvenile spiders displayed an overall preference for long(red)and short(purple)wavelength colors.Thus,differences in color were not particularly important for E.tricuspidata regarding visual attractiveness and selection.However,inflorescence shape(e.g.,tulip)was found to be a more desirable trait for selection,which was likely due to the provision of shelter.Our results also suggest that male preference for female spiders depended somewhat on the background color(wavelength)of the flower on which the female was located.We assumed that spiders on different colored backgrounds may exhibit different overall brightness and spectra,and that on a red background with a high wavelength they would appear to have a higher overall contrast,which would attract males.3.Volatile scent preference of Ebrechtella tricuspidata for host flowers:In the floral scent preference experiments,there was no significant preference for limonene,?-ocimene and linalool from the four monoterpene aromatic compounds.However,the spider showed significant approach-avoidance to ?-pinene,indicating that the spider had a strong aversion for ?-pinene.For the four benzene aromatic compounds,the spiders did not show significant preferences or approach-avoidance behavior.There was also no significant difference in the time of selection among eight aromatic compounds.