Study On Metapopulation Structure Of Aphidphagous Syrphids And Biological Characteristics Of Important Species In Changsha

The aphidophagous syrphids is a common predatory natural enemy insect in the agroforestry and the gardening.The larvae feed on different species of aphids and low instar larvae of Lepidoptera and other Hemiptera pests.The adultsare common pollinators in the field which feed on pollen and aphid honeydew.Periodic surveys were conducted on aphidophagous syrphids in all kinds of farmland,tobacco field,tea plantation and surrounding green belt plants in Changsha during the period of 2016-2018 which determined the abundance and composition ofaphidophagous syrphids communities.The collected syrphids specimens were identified by morphological and molecular biological identification methods.The dynamics and living habits of mainly aphidophagous syrphids were observed and studied emphatically,which corresponding biological characteristic tests was designedfor different species of aphidophagous syrphids.Thelaboratorial rearingtechniques of mainly aphidophagous syrphids has been studied and mastered.The main results of this study are as follows:According to the survey,there were two dominant populations of aphidophagous syrphids in Changsha: E.balteatus and B.serarius.E.cretensis,I.scutellaris,P.tibialis,E.confrater and S.macrogaster were rich populations.M.orientale,E.corollae,E.latimacula,S.scripta,S.selenitica,M.scalare,S.torvusand E.latifasciatuswere common populations.E.balteatus occurred most frequently with the early occurrence time and the long duration time.E.balteatus adult can be seen all year round and larvae can feed on a relatively large amount of aphid species.1.6 kinds of aphidophagous syrphids adults had been morphologically identified the specific gene COI in mitochondrial DNA by means of PCR-grade column animal mitochondrial DNA kits.The result indicated that the consequent of the two methods of identification were highly consistent.2.Predation functional response type of E.balteatus larvae to T.aurantiii belonged to Holling-II type with large resistant to starvation endurance.Under the condition of constant humidity and photoperiod,the development rate of E.balteatus larvae was proportional to time at temperature of 15-30°C.3.B.serariuswas a dominant population with6 to 8 generationsa year in the tea plantation.The developmental period of B.serariuslarvae was shorten and pupa got the heaviest weight and the higheremergence rate by feeding on Toxoptera aurantii.4.S.macrogasterwas a dominant population with 7 generations a yearin the habitat of the tobacco fields.The developmental rate oflarvae was proportional to temperature under the temperature range of 16 to 28? with constant humidity and photoperiod conditions.5.The developmental period of Diplazon laetatorius Fabricius decreased gradually with the increase of temperatureUnder thecondition of constant humidity and photoperiod,temperature of 15-30°C.The purpose of this study is to provide the theoretical basics for the applicationin field control in changsha and the data support for indoor propagation and commercial production and transportation of aphidophagous syrphids.