Impact Of Global Warming Temperature Patterns Simulation On The Population Dynamics Of Plutella Xylostella

Gobal warming have directly effect on ectotherms, in particular development, survivorship, reproduction, geographical distribution, phenological period, species richness, relationship of host plant and herbivorous insect and pest-natural enemy of the core life activity of insect. So far, there have been a large number of researches on the effect climate warming on insects. The tested insect was forced to live under the different constant temperature and simple fluctuation temperature in most experiments for studying effects of climate wanning on insect. Result from those experiment cannot demonstrate how the global warming in the field influence the population development of insectAs the most important pests of cruciferous vegetables in the world, diamondback moth Plutella xylostella (L.) was used to study. We designed a set of experiments simulating the characteristic of glodbal warming, such as rising mean temperature and reducing thermal fluctuation in the field and setting the different global warming patterns to reveal the effect of the global warming on population dynamics, overwinter and long disatance migration of the diamondback moth. The results are potentially used for improving prediction accuracy and innovating new control strategies of diamondback moth.Fistly This paper mainly studies, we set the fluctuation temperature with 24h simulating the diurnal temperature range in the field, designed 20 global warming patterns assembled three mean temperature with seven thermal fluctuation, and studied the effect different global warming patterns on development, survivorship, reproduction, longevity of high temperature population, moderate temperature population and low temperature population of diamondback moth. Main conclusions:for high temperature population, as the characteristic of globe warming, the increasing mean temperature with reducing thermal fluctuation promoted the development of egg, larva and pupa, and improved the hatching rate and pupation rate. When the variation of environmental temperature was lower the suitable thermal fluctuation, the globe warming reduced the adult longevity and deceased the adult production. For moderate temperature population, as the characteristic of globe warming, the increasing mean temperature with reducing thermal fluctuation shortened the development time of egg, larva and pupa. When the variation of environmental temperature was lower the suitable mean temperature, the globe warming improved the hatching rate and pupation rate. When the variation of environmental temperature was lower the suitable thermal fluctuation and below the suitable mean temperature, the globe warming reduced the adult longevity and deceased the adult production. For low temperature population, as the characteristic of globe warming, the increasing mean temperature with reducing thermal fluctuation promoted the development of egg, larva and pupa. The increasing mean temperature enhanced the hatching rate, pupation rate and emergence rate, but the reducing thermal fluctuation inhibited the survival of egg, larva and pupa. The globe warming significantly reduced the adult longevity. When the variation of environmental temperature was lower the suitable thermal fluctuation, it inhibited the adult production.Secondly, we tested the survival rate of overwintering in Shenyang, Beijing, Huiming, Anyang, Zhu madian, Wuhan, Changsha and Guangzhou from November 2008 to February 2009, analysised the insect source of the spring occurrence, investigated the No. of trapping adult in 11 regions.such as Ha erbing, Shenyang, Gong zhuling, Beijing, et al,during the spring season in 2009, used HYSPLIT to simulate the long disatance migration trajectory of the diamondback moth, combined with amount of meteorological data, made a synthesis of the effect of global warming on the ovwewinterng and long distance migration in China. The main results were displayed as follows, according to the field overwintering experiment in Shenyang, Beijing, Huiming, Anyang, Zhu madian, Wuhan, Changsha and Guangzhou from November 2008 to February 2009, it was determined primarily that the overwintering arear of the diamondback moth could be classified into three kinds:the overwintering arear, scattered-overwintering arear and non-overwintering arear. Non-overwintering arear was in north of Beijing, scattered-overwintering arear was in north of Zhu madian and in south of Beijing, in which the 4th instar larva could overwinter on the defoliation or the stubble, the overwintering arear was in south of Zhu madian, in which the 4th instar, pupa and adult could overwinter on the defoliation or the stubble. As a result, the occurrence souce of the diamondback moth in spring was local population in south arears of Zhu madian, the occurrence souce of the diamondback moth in spring was not local population in north arears of Beijing, might be caused by the immigration from another place. The results of the occurrence situation of the diamondback moth adult in the field in Ha erbing, Gong zhuling, Shenyang, Beijing, Dalian, Gucheng, Anyang, Zhu madian, Nanjing, Hefei, Wuhan from April to May in 2009 have showen there were 4 times homochronous sudden increasing appearances from the south of China to the northeast of China,4 times homochronous sudden increasing appearances were like tegular arrangement Consequently, the occurrence source of the diamondback moth in northern China during the spring season was migrated from the overwintering arear in southern China.Rising mean temperature and reducing thermal fluctuation induced by the global warming directly impacted the density of insect in overwintering arears and the emergence period of overwintering pupe, and the occurrence arear and the damage degree in southern China, indirectly impacted the occurrence period, the occurrence arear and the damage degree of the diamondback moth in northern China. Recently the global warming led to the rising mean temperature and reducing thermal fluctuation in winter in China, and caused the increasing survival rate of overwintering in various in China, this directly impacted the overwintering divison would shift northwards into the north, tne overwintering arear would keep enlarging to the north, the damage arear would be increased. For the long distance migration of the diamondback moth, the characteristic of global warming could directly impact the long distance migration, but could lead to the increasing density and the earlier emergence period of overwintering insect, and cause the occurrence period of pupation early and the frequency of emmigration with increasing frequency, this would lead to increasing the occurrence period, enlarge the occurrence arear and aggravate the damage degree. It followed that the global warming had profound effects on the occurrence distribution range and damage arear of the diamondback moth.