| With the rapid development of nitrogen production technology,the application of low-temperature combined with controlled atmosphere to control grain storage insects is increasingly extensive.The lethal effects of controlled atmosphere of high nitrogen against Sitophilus oryzae（L.）and Plodia interpunctella（Hübner）were assayed at different temperatures.Explored the degree of delay for killing time against insects in high nitrogen atmosphere at low temperature.The effects of high nitrogen atmosphere on the development,reproduction and survivorship of insects were determined when the exposure times were insufficient.Besides,the behavior response of adult for S.oryzae and larva for P.interpunctella who are in controlled high nitrogen were monitored.The relationships between behavior response ratio and exposure time of population extinction were analyzed to predict the insect death and the exposure time of full mortality coming.The major conclusions are as follows:（1）The efficacy of high nitrogen atmosphere against eggs,larvae,pupae and adults of S.oryza all showed a significant decrease at lower temperature.The exposure time of full mortality was 25 d at 18°C,which was delayed 6 and 12 d corresponded to 23 and 28°C.Compared with 23 and 28°C,the exposure time of 100%mortality of eggs at 18°C was delayed by 4 and 10 d,4 and 8 d of larvae,6 and 12 d of pupae,6 and 10 d of adults.The order of tolerance to controlled nitrogen atmosphere against different stages of S.oryzae was pupa>egg>larva>adult.Temperature had significant effect on the lethal exposure time,and increase of the temperature sufficiently decreased the lethal exposure time.The minimum lethal exposure times required to kill all stages of P.interpunctella were about 20,16 and 12 d at 18,23 and 28℃,respectively.The exposure time to achieve 100%mortality of eggs,1st and 2nd instar larvae,4th and 5th instar larva and pupae at 18℃was 4,6,8 and 6 d longer than that at 28℃,respectively.The tolerant order of different stages of P.interpunctella from the highest to lowest was:4th and 5th instar larvae>1st and 2nd instar larvae>pupae≥eggs.（2）The hidden stages of S.oryzae that were deviated from the controlled environment of 98%N2 can still develop from immature stages to adults when the exposure times were insufficient.The developmental duration can be extended at lower temperature.The developmental period of F1 generation of S.oryzae that had been exposed in high nitrogen atmosphere was prolonged significantly.It took at least 26 d for F1 generation of S.oryzae to develop from egg to pupa with a survival rate of 70%exposed in high nitrogen atmosphere,and 34～37 d to develop from egg to adult that crawlled out of grain kernels.The whole generation developmental period of S.oryza was prolonged nearly 10 d.The inhibition effect of controlled atmosphere of high nitrogen on F1 generation was more significant as F0 generation of S.oryzae had a lower survival rate.There were significant differences between different survival rates in body length of larvae and body width of the four instar larvae.Other stages had no significant difference in the body length,body height,body width and head capsule width of F1 generation of S.oryzae.（3）The developmental period,pupation rate,survival rate and fertility of F0 generation of P.interpunctella was influenced significantly by temperature.The inhibitory effect on growth and development was more significant with lower survival rate after exposed in high nitrogen atmosphere.The time of pupation was 8 d from the fifth instar larvae with survival rate of 70%after exposed in high nitrogen atmosphere.It was nearly 2 times longer than that of exposed in air,1d longer than that of 80%survival rate and 1 time longer than that of 90%survival rate.The survival rate of P.interpunctella exposed in air from fifth instar larvae to adult was 86.11%,and P.interpunctella with 70%,80%and 90%survival rates after exposed in high nitrogen atmosphere was 18.33%,32.60%and 55.56%.The fertility of F0 generation of P.interpunctella was effectively inhibited after exposed in high nitrogen atmosphere.The fertility of F0 generation of P.interpunctella exposed in air was 122.83.The inhibition ratio of fertility for F0generation of P.interpunctella exposed in 98%nitrogen atmosphere with 70%,80%and 90%survival rates were 33.92%,46.68%and 71.23%.The survival rate of F1 generation of P.interpunctella was significantly reduced after exposed in 98%nitrogen atmosphere,which was 43.33%exposed in air,and F1 generation of P.interpunctella with 70%,80%and 90%survival rates after exposed in high nitrogen atmosphere was 22.33%,30.33%and 36.67%.The total developmental period of F1generation of P.interpunctella was prolonged after exposed in 98%nitrogen atmosphere.Compared exposed in air,the F1 generation of P.interpunctella with 70%,80%and 90%survival rates were delayed by 4,2 and 1 d,respectively.Compared with F0 generation of P.interpunctell,the inhibition ratio of fertility for F1 generation of P.interpunctell decreased obviously.The inhibition ratio of fertility for F1generation of P.interpunctella exposed in 98%nitrogen atmosphere with 70%,80%and 90%survival rates were 1.14%、13.55%and 8.02%.The population trend index increased significantly with more survival rate of F0 generation.The population trend index of P.interpunctella exposed in air was 28.11.The population trend index of P.interpunctella with 70%,80%and 90%survival rates after exposed in 98% nitrogen atmosphere were 15.74,17.96 and 25.37.（4）The temperature had distinguished influence on different life stages of S.oryzae when they stayed in 98%N2mixed with air,not only for exposure time of abnormal response and knockdown ratio,but also for exposure time of full mortality.Compared with 23℃and28℃,the time of 100%abnormal response for adult of S.oryzae at 18℃was delayed by 3.55d and 6.76 d,respectively.The time of 100%knockdown was more than doubled from 28℃to 18℃.The time of behavior change was objectively increased with the abnormal response ratio went up at each temperature,and varied to lower with temperature went to higher.When all adults of S.oryzae showed abnormal behavior,it still needed at least 12.86,10.41 and 7.62d to ensure the complete death of S.oryzae at 18,23 and 28℃.When all adults of S.oryzae were knockdown,it still needed at least 10.27,9.10 and 6.71 d to ensure the complete death of S.oryzae at 18,23 and 28℃,respectively.（5）Temperature influenced the time of different reaction ratios for the larva of P. interpunctella significantly.At 18,23 and 28℃,the time of all larvae of P.interpunctella with motionless in 98%nitrogen environment was 14.86,12.51 and 9.88 d,respectively.The time of behavior change was objectively increased with the motionless ratio went up at every temperature.The time of different motionless ratio varied from 3.18d to 14.86 d at 18℃,2.07d to 12.51 d at 23℃and 1.42 d to 9.88 d at 28℃.When all larvae were motionless,the time of full mortality of P.interpunctella exposed in 98%nitrogen atmosphere was at least 5.14 d at18℃,3.49 d at 23℃and 2.12d at 28℃,respectively. |
