Survey Of Population Dynamics For Parasaissetia Nigra Nietner

Rubber planting area of china is located in the northern margin of tropics. Through over50years'exploration and ceaseless optimization and adjustment, three advantaged natural rubber production area respectively in Yunnan, Hainan, and Guangdong are basically formed. With the significant development of rubber industry, the outbreak and development of rubber diseases and insect pests becomes more and more common. Parasaissetia nigra Nietner is one of the most important factors that restrict dry glue output of rubber. It was found as hevea brasiliensis pest in1989in Dadugang of Yunnan. The large area outbreak of it occurs in2004in Xishuangbanna rubber plantation, with damage area of13,000hm2. The branches and leaves of damaged rubbers are densely covered by scale insects. Leaves become dried-up and yellow and then shrivel even die. Subsequent dark mildew causes leaf loss, which has severe impact to the growth of rubber tree and the output of dry glue.Parasaissetia nigra Nietner is a Homoptera Coccidae Parasaissetia Takahashi insect, Parthenogenetic reproduction, and distributes in tropics and subtropics. Investigation on Impact Factors of Parasaissetia nigra Nietner field population can know the generation condition of Parasaissetia nigra Nietner population effectively, forcast its outbreak accurately, and provide scientific guidance for the prevention and control of it.Impact Factors of Parasaissetia nigra Nietner field population are affected by various aspects, mainly including biotic factors and abiotic factors. Abiotic factors mainly include rainfall, temperature, and humidity, etc. Biotic factors mainly include anthropogenic factor, natural enemy factor, pathogenic microorganism factor, and other biotic factors.Parasaissetia nigra Nietner undergoes winter in the form of overwintering adults, with remarkable overlapped generations. According to field observation records of 2011, determined by removal method, Parasaissetia nigra Nietner can reproduce for5generations within one year on rubber nursery stocks in Danzhou of Hainan province. The overwintering survival rate of Parasaissetia nigra Nietner on rubber nursery stocks is very high, reaching76%in area with highest rate and55%on average.The life cycle of Parasaissetia nigra Nietner for a year. Parasaissetia nigra Nietner overlapping generations,2011year field observation records,and use removal method Statistics of Parasaissetia nigra Nietner can sire five dynasties a year.In addition to October to the second year february,all of instars can be finded.But January have only overwintering and the end of this month zhe overwintering start spawning.Rainfall, temperature and humidity reflect on the influence of Parasaissetia nigra Nietner's population. Rainfall is influenced by temperature and humidity to directly affect the Parasaissetia nigra Nietner's occurrence in field populations. As investigations showed, Parasaissetia nigra Nietner could adapt to high temperature and dry environment, and also have certain tolerance of low temperature and high humidity. As like in the low temperature with cold conditions, Parasaissetia nigra Nietner's generation time had lasted for longest more than4months in the wild to resist the bad environment. Although suffered the strong rainfall and typhoon last year, the majority of rubber branches damaged, leading the parasitic condition worsened, but Parasaissetia nigra Nietner population increased than last year, indicating that it had relatively strong tolerance on Hainan climate, there would most likely be a massive outbreak under a suitable climate condition.Host plant factor for Parasaissetia nigra Nietner. It seriously harmed the grafted rubber seedling as the main host plant in Danzhou, highest as45%, but did relatively light harm to the old cut tree, only about1%. Natural enemy factor for Parasaissetia nigra Nietner. Surveys showed that Metaphycus parasaissetiae, Coccophagus ceroplastae, Crematogaster rogenhoferi and some predatory mites were main natural enemy biologies. Among them, Metaphycus parasaissetiae accounted for Parasaissetia nigra Nietner populations of11%, to be the highest proportion,followed by Crematogaster rogenhoferi's predation. The test chose Crematogaster rogenhoferi, which is a higher density of the natural enemy biology, to breed and field cast, to prove that it had relatively obvious control effect on field populations of Parasaissetia nigra Nietner and Anoplolepis longipes after its release.Pathogenic microorganisms and its effects for Parasaissetia nigra Nietner. A schersonia kawakam ii Saw parasitics not common of Parasaissetia nigra Nietner,lots of serious damage rubber tree have not A schersonia kawakam ii Saw。This shows that A schersonia kawakam ii Saw and Parasaissetia nigra Nietner are disproportionate。 In the survey75rubber trees, only5rubber trees have A schersonia kawakam ii Saw, which is accounted for the total number of6.7%.And the average parasitism rate is2.9%Other biological factors for Parasaissetia nigra Nietner. it is mainly about Anoplolepis longipes. Anoplolepis longipes could affect Parasaissetia nigra Nietner on protection and cleaning, and help them drive off the natural enemy. What's more, Parasaissetia nigra Nietner could provide Anoplolepis longipes honeydew, and it's population scale could be relatively high cared by Anoplolepis longipes, the quality of life and reproduction rate were significantly higher than that of control. However, both exist alone can independently finish the life throughout the history, were the original collaboration.Human activities can affect Parasaissetia nigra Nietner's occurrence of populations. (1Agricultural cultivation measures:1) Scientific field management, can effectively reduce the damage to plant from Parasaissetia nigra Nietner.2) Trim rubber seedlings.3) Far from anyother Host plants for Parasaissetia nigra Nietner,and Avoid cross-contamination.(2) The use of chemical pesticides to Parasaissetia nigra Nietner. The test result showed that5%Acetamiprid emulsion and1.8%Abamectin emulsifiable concentrates had the best killing effect on Parasaissetia nigra Nietner among the5kinds of pesticides.