| Northeastern China is one of the main maize producing areas in China.The Maize planting scale,mechanization degree and corn yield axe all higher than the national average level.Asian corn borer Ostrinia furnacalis(Guenee)which is widely distributed and ecological adaptable,is one of the main pests of corn and seriously cut down maize yield and quality.In recent years,the global warming trend is obvious,especially in the northeast region.With climate changes,the development of O.furnacalis is largely affected,the growth rate may accelerate,the occurrence period might shift to an earlier date and generations will increase;and the field occurrence may vary for growth time prolonging and the planting density increasing of corn main cultivars.All these changes eventually have prompted a change for generation spatial pattern of O.furnacalis in different regions.In order to clarify the changes of generation spatial pattern of O.furnacalis in the northeastern China.on basis of clear the effect of corn planting and sowing time on O.furnacalis occurrence,the generations regionalization of O.furnacalis was defined from Heihe(50 13'41.14 N)of Heilongjiang province to Lvshun(38 56'8.08 N)of Liaoning province.And combined with meteorological observation data,the generation spatial distribution map of O.furnacalis in northeastern China was formatted by means of GIS system,and at the same time the initial period and future generations of O.furnacalis for different regions in northeastern China were predicted.The results may sever as reference and guidance for prediction and IPM of O.furnacalis under the condition of new planting and farming system.For the corn borer overwintered with mature larva in northeastern China,overwintering larvae amount and survival directly affect the occurrence of Asian corn borer next year.Whether the overwintering larvae can overwinter safely and become effective source next year,it directly relate with its biology and natural parasitic situation.It has important theoretical and practical significance for population monitoring and IPM of Asian corn borer to clear the overwintering larvae situation and carry out biology research in northeastern China.Therefore,the distribution of corn borer in corn plants,overwintering larvae instar distribution,survival rate,parasitoid species and parasitism rate were investigated.Furthermore,the dynamic hardiness and HSPs expression under low alternating temperature stress of diapause larvae was studied.Understood the physiological changes,hardiness dynamic and HSPs response under low temperature had provided basis for further study on physiological and molecular mechanism of Asian corn borer hardiness.Finally,according to the field occurrence amount and meteorological data in Shenyang,models were built with stepwise regression and BP neural network,and the occurrence dynamics of Asian corn borer first and second generation occurrence were predicted.The main results are as follows:1.Through the systematic investigation and analysis of the growth and development process of corn borer in different regions,generation district was defined.District north to Harbin of Heilongjiang province is one generation zone of O.furnacalis,District from Harbin to Gongzhuling of Jilin province is incomplete 2 generations zone,that is the first and the second generation mixed area;District from Gongzhuling to Shenyang of Liaoning province is complete 2 generations zone;and district south to Shenyang is incomplete 3 generations zone,which is the second and the third generation mixed area.2.Through spatial interpolation analysis meteorological monthly data of 1981-2010 outside 211 meteorological station which located in the Northeast(including Eastern Inner Mongolia)using geographic information system software ARC/INFO 10.3 by ordinary Kriging(Ordinary Kriging),Cokriging(CoKriging)and inverse distance weighting(IDW)respectively,and combined with the effective accumulated temperature of corn borer,we got the whole Northeast(including Eastern Inner Mongolia)generation spatial distribution map of Asian corn borer.The interpolation result is consistent with the result of the investigation.3.With the effective accumulated temperature law,combined with long-term observation data of Shenyang area,the initial period of O.furnacalis of 13 regions of the Northeast was forecasted,and the prediction results consistent with observation data.4.The available degree-days and concurrent generations of O.furnacalis will increase in future in northeastern China.By 2050,the generations of O.furnacalis in Keshan,Jiamusi will probably increase 1 generation;Changchun,Siping and Changtu which are 2 generations zone now will become 2 and 3 generation mixed area;and the 3 generation rate of whole population will increase in Shenyang and Pulandian.5.Overwintering larvae are mainly concentrated on the ear of corn plant(14.29%-62.08%),but with the increase of latitude the distribution gradually spread to the whole plant.In most regions of Northeast China,Asian corn borer larvae overwintered in instars of 4th and 5th,however,some overwintered in instars of 3rd in several area.The percent of 4th instars overwintering larvae are between 2.8%?26.37%,and the percent of 5th instars overwintering larvae are more than 70%.The survival rate before overwintering is more than 87.30%at all these sites,while the rate after overwintering is between 48.22%?73.00%.6.The SCP of different populations were within-5 ??-25 ?,and FP were within-2.5 ??-15?,as the environmental temperature reduced,SCP and FP of Asian corn borer were decreasing and cold hardiness enhanced,both showed trend of fall first then rise,and the minimums were found in January or February;Water contents were within 50-70%,showed a trend of decline after rising first,consistent with the environmental temperature and SCP change trend,and the maximum was found in April,the lowest Water content was increased from north to south(r=-0.758,n=12,p<0.01).Lipid content basically in 45-70%range,showed trend of rise first then fall,and the highest Lipid content was decreased from north to south(r=0.697,n=12,p<0.01).Cold hardiness of Asian corn borer larvae(the lowest SCP and lowest FP)was significantly correlation with the lowest Water content and highest Lipid content(p<0.01),It was better in high latitude area than that in low latitude area,the change of Water content and Lipid content was related to the cold hardiness,the more environment temperature decreased,the more cold hardiness enhanced,also the more cold hardiness difference between different geographic populations were reflected.7.Asian corn borer diapause larvae after alternating temperature treatments,the relative expression of Hsc70 and Hsp90 gene were detected using qPCR,and with analyzed by SPSS,Hsc70 and Hsp90 genes were found in response to low temperature.The expression were significant increase in recovery phase and after recovery 3 hours the relative expression of two genes were maximum,rather than in low temperature induced phase.It plays an important role for Asian corn borer with Hsc70 gene and Hsp90 gene in the recovery phase to repair damage.8.There was relevant relationship between occurrence quantity and the multiple factors,the prediction model could be used to predict the occurrence quantity of the corn borer and Trichogramma.The simple stepwise regression model was more reliable than the multiple factor interactions regression model to predict the occurrence quantity of the Maize borer and Trichogramma except for the corn borer spawning quantity of the second generation.With the same data,modeling by BP neural net,the eggs amount,incubation eggs and parasite eggs were forecasted,and the result was more close to observed data. |
PDF Full Text Request