Studies On The Overwintering Spatiotemporal Dynamics And Pollution-free Controlling Of Aleurocan Spinfetus In Tai'an Tea Garden

Aleurocan spinfetus?Quaintance?is one species of serious insect pests on tea trees in China.Due to its small-sized body,high reproductive potential and concealed damage,the control for the pest is more difficult.While it damages tea trees,it secrets honeydew and causes sooty disease on the tea leaves,affecting the yields and quality of the tea leaves.Therefore,the pollution-free control for the pest is an urgent problem expected to be solved in the actual production process of organic tea garden,which has high practical value.The occurrence and control measures of overwintering A.spinfetus were studied in order to provide a theoretical basis for the pollution-free control of A.spinfetus in Shandong tea garden.1.The spatial distribution patterns of A.spinfetus wintering nymphs in tea tree crown and the distribution of wintering eggs and different instar nymphs in different layers of tea crown were researched.The spatial distribution patterns of A.spinfetus nymphs belonged to uniform distribution,the mean of aggregation?in every months were over 2,suggesting that the aggregation of A.spinfetus nymphs arose from the oviposition habits of the pest or some environmental factors.The acceleration rate of aggregation of basic elements decreased with the change of population density,and diminished by 0 in November.The number of 1^stt instar nymphs gradually increased from lower layers to upper layers.The 2^nd instar nymphs distributed mainly in the middle and lower layers from the beginning,then spread to upper,middle and lower layers uniformly.The overwintering 3^rd instar nymphs changed from the middle and lower layers to aggregating in the middle layers.Eggs were distributed in the middle and lower layers throughout the winter.2.Mortality rates of overwintering A.spinfetus pseudo pupae at low temperatures were continuously determined from early October to the middle March next year.The results showed that mortality rates of the pseudo pupae at-15?were higher than those at-10?.All the temporal orders of sizes of the mortality rates in both temperature treatments were uniformly 12 h>8 h>4 h>2 h.The change tendency of mortality rates over the seasons were relatively high in October,and then lower from November to January next year,and high after February.3.In indoors,at 25?±1?the predation function responses models of two species of lacewings?Chrysopa pallens and Chrysoperla sinica?to A.spinfetus were modeled,showing the two lacewing have good predatory effects on A.spinfetus.Meanwhile,the interference and density effects of two species of lacewing larvae were simulated with two models,indicating the interference effect increased with the increase of the density of the lacewing larvae in the unit space.In addition,when the densities of A.spinfetus and lacewing larvae increased with same proportions,obvious internal interference between the lacewing larvae occurred.4.Three insecticides were used to determine the insecticidal effectiveness of A.spinfetus nymphs.The results showed that all three insecticides had better insecticidal effectiveness on the pest.CITROLE mineral oil last for more than 21 days,and it still has good control effectiveness lasting 35 days after the application of the mineral oil.The lasting effectiveness of the mixture of thiamethoxam and difenthrin and difenthrin was only about 7 days,and the efficacy and lasting duration of the CITROLE mineral oil were significantly higher than that of the mixture and difenthrin.