The Coupling Relationship Of Plant And Insect Diversity By Specific Plants-Ants-Aphids And Mealy-bugs Mutualism

Songnen grassland is one of the most important grazing grasslands in Northeast China and is subjected to serious degradation due to over grazing and reclamation.The degradation of this grassland has led to soil alkalinity which adversely affects ants and plants diversity by altering ecological processes.Ants are common species in the grassland that play a critical role in the grassland ecosystem through a symbiotic relationship with specific soil organisms besides their influence on soil physicochemical properties.The present study was aimed at understanding the relationship between ant diversity and plant diversity under different degraded grassland along with the factors that affect the diversity at multiple trophic levels;and to understand the symbiotic interaction between ants,aphids,and plants at multiple trophic levels and the deriving factors that governs this interaction.The experiment was randomized complete block design and conducted in Songnen grassland and Northeast Normal University.Grassland was divided into heavy degraded and light degraded sites based on saline alkaline patches.Dominant ant species of heavy degraded site was Lasius flavus while in light degraded site was Lasius alienus.We investigated ant diversity,the distribution pattern of the mounds,plant biomass and diversity,the number of insects per plant,root architecture and nutrients of major plant species.Similarly,in laboratory experiment,we selected three plant species i.e.,Artemisia scoparia,Leymus chinensis,and Setaria viridis while one ant species i.e.L.flavus,aphids,and mealy-bugs.In total,4 treatments were used to study the coupling relationship of plants and insects diversity by specific plants-ants-aphids and mealy-bugs mutualism.The main results are present as follows:(1)The Songnen grassland degradation changed ant diversity by manipulating the ecological niche of ants.(2)Ant mounds showed heterogeneous distribution in heavy degraded sample plot showing that ant colonization is derived by grassland degradation.In contrast,homogenous and balance distribution of ant mounds was recorded in light degraded sample plots.(3)L.chinensis,Calamagrostis epigejos,A.scoparia,Kalimeris integrifolia,S.viridis,and Artemisia anethifolia were the main species in grassland experimental site.Nutrient components analysis revealed that the root water contents of A.scoparia and A.anethifolia were relatively lower as compared to other species.Root length and surface area of A.scoparia were higher than other plant species.Hence,A.scoparia is more likely to provide suitable habitat conditions to aphids and change animal diversity by its morphological features.(4)The number of parasitized aphids and mealy-bugs were significantly higher on the roots of A.scoparia and A.anethifolia.The decisive factor that attracted ants to A.scoparia was the root architecture and ants presence which together provided suitable ecological niche to aphids and mealy-bugs.This concludes that plant diversity affect animal diversity by modifying ecological amplitude of animal species and providing suitable habitat.(5)Quantitative analysis of ants showed that ants were more numerous on A.scoparia plants particularly in those treatments having aphids and mealy-bugs.The detrimental factor to attract ants was the presence of mealy-bugs and aphids which provide honeydew to ants as their source of nutrition.Each plant species provided specific ecological niche to ants and hence governed their distribution.In conclusion,insects have a broad impact and important ecological significance on plant diversity in Songnen grassland.L.alienus and L.flavus indirectly affect plant communities by changing the physical and chemical properties of the soil.The symbiotic relationship between ants,insects and plants has a direct impact on the plant community diversity.Morphological attributes such as roots of plants have a huge impact on governing mutualistic relationship between different insects.Our study has raised new questions about the association of ants,aphids,and plants.It is recommended to screen phytochemical profile of A.scoparia roots and aphids biochemistry to know the driving agents of this interaction at biochemical and molecular level.