The Response To The Global Climate Change And The Adaptation Mechanism To Extreme Temperature By Ostrinia Furnacalis (Guenee)

Asian corn borer (ACB)(Ostrinia furnacalis(Guenee)), distributed widely due to its strong ecological adaptation, is the most important pests which cause enormous damage to maize production. Insect, as a poikilotherm, would been effected deeply by global climate warming.Field survey and analytics of historical date, population fluctuation both ACB and its natural enemy and the effects of drought and flood to ACB were carried out to clarify the influence on population fluctuation of ACB under the global climate warming.The cold-resistance strategy, freeze resistance ability and the diversity of different geographical populations of ACB by measuring the supercooling points (SCP) and by exposing to low-temperature were also studied. Response and adaptation mechanism of ACB to extreme temperature stress were conducted by biochemical, mRNA differential display (mRNA DD-PCR) and proteomics techniques. The results are as follows:1. Systematic survey result showed that annual egg-laying period of ACB had been prolonged over the past decade in Shenyang region. The egg-laying end date of1st generation was prolonged about lOds. The egg stage period of1st generation ACB increased and the oviposition interval between1st and2nd generation decreased in Shenyang. The eggs of3rd generation ACB were founded and it could grew partially to mature larva and overwintered safely, It could be concluded that Shenyang region was transformed from the two-generation zone into the two and three mixed generations zone of ACB.2. An amount of ACB oviposition was very high in field in Shenyang. The oviposition amount of1st and2nd generation was2992.67eggs/centgener plot and8746.33eggs/centgener plot respectively. The oviposition amount of2nd generation decreased significantly over the past decade. The major natural enemy of ACB during the egg-laying period was Trichogramma and parasitism rate was2%-15%in1st generation egg occur period. The parasitism rate increased with the prolonging of ACB1st generation egg-laying period. The parasitism rate was40%-70%in2nd generation egg-laying period, and reached90percentage above at the later period of2nd generation egg-laying period. The ACB overwintering mortality was high in Shenyang (45%-65%).3. It was found that the ACB population decreased sharply due to lasting drought during June to September in2009in Beipiao county (Liaoning province) and ACB1st generation ACB population is lower next year, however2nd generation ACB population at that year restored to normal amount. No significant ACB population fluctuation was observed under the condition of flood disaster in Tieling city (Liaoning province) at the end of July in2010.4. Freeze-resistance capability and tactics of wild diapause ACB larvae were compared among seven ACB geographical populations, which were collected from Jiamusi, Dehui, Gongzhuling, Shenyang, Wafangdian, Pulandian, and Lushun in Northeast China by measuring the supercooling point (SCPs) and by surveying the low temperature survival rates. The results showed that the range of SCPs was-6.18--29.98℃and had significant difference(P<0.05) among the seven geographic populations. No strict correlation between the SCPs and the geographic latitudes of population was observed. The mortality had significant difference(P<0.05) among the seven geographic populations and the mortality decreased with the increasing latitudes after12h cold exposed, the Median lethal temperatures (LT5o) decreased with the increasing latitudes and had significant difference(P<0.05)(-52.19～68.19℃). No death was observed the-30℃above after12h cold exposed. The mortality increased with the temperatures decreased below the-30℃. However, part of ACB individual could resistant-80℃. after12h frozen. So the cold-resistance standard of ACB was not SCP but survival rate of low temperature and LT50.5. The freeze-resistance capability and relative body content of diapaused ACB overwintering larvae were studied during October2012to March2013. The results showed that the larvae freeze-resistance capability changed with temperature alteration. The water and protein contents within the ACB body descended gradually in winter. The fat which made up the highest percent of body dry matter in that time, reached62.51%at end of December. Glycerin, reached170.96mg/ml at February, took the highest hemolymph content. The correlation between Median lethal temperatures and the lethal temperatures alteration was significant (P<0.01). The alteration of lethal temperatures was significant negative correlated with the alteration of dissociative fat content (P<0.05), and was positive correlated (not significant, r=-0.802, P=0.055) with the alteration of glycerine content possessing in hemolymph. The alteration of lethal temperatures was significant correlated with alteration of glycerine content (P<0.05). In conclusion, the fat and the glycerin are the two main freeze-resistance substances of ACB. Moreover that plenty of mannitol accumulated was found in the hemolymph of diapause ACB larvae.6. The gene expression of ACB at0℃and4℃under rapid cold acclimatization test was carried out by using the mRNA DD-PCR technology. The results showed that there were154and170difference zones through reverse transcription of total mRNA after test, and121and141single stripe were obtained through secondary amplification respectively. No specific gene transcription was found after rapid cooling domesticated of ACB through the reverse Northern blot. In conclusion, ACB could response to rapid cooling acclimatization by activating specific protein, adjusting substances content, changing the conformation of the membranes and regulating some specific gene expression.7. The ACB haemolymph protein group of freezing and resistance to freezing were identified by two-dimensional electrophoresis. The results showed there were24proteins with two fold expression differences.21points were identified successfully after mass spectrometry analysis, including17up-regulation expressions and4down-regulation expressions. These protein play an important role in metabolism, energy supply and defense reaction of insects...