低温对小菜蛾取食的影响

发布时间：2018-03-19 11:58

本文选题：小菜蛾　切入点：低温　出处：《中国农业科学院》2016年硕士论文　论文类型：学位论文

【摘要】：小菜蛾是十字花科蔬菜重要害虫,在中国的越冬问题一直未有明确结论,越冬虫态及越冬地理分布尚不清晰。本文拟从低温和取食的角度探究小菜蛾的越冬情况,从如下四个方面研究低温和食物对小菜蛾存活的影响:测定小菜蛾幼虫停止和开始取食的低温阈值;明确不同取食状态下小菜蛾幼虫的抗寒性;明确阶段性取食对小菜蛾冬季存活的影响以及春季寒潮下小菜蛾生命参数变化,得到了如下结果:1测定了小菜蛾幼虫停止和开始取食的低温阈值。在1-13°C恒定温度下处理4h,记录发生取食行为的幼虫头数,结果发现2龄幼虫在2°C时即停止取食,3龄和4龄幼虫在1°C时停止取食。设计逐渐降温和升温过程,即温度从20°C以0.2°C/min速率降至-9°C,平衡15min后以0.2°C/min速率升至20°C,测定降温过程中幼虫停止取食温度和升温过程中开始取食温度,结果发现:3龄幼虫停止取食温度为4.7°C,开始取食温度为12.2°C。4龄幼虫停止取食温度为4.6°C,开始取食温度为12.6°C。2明确了低温和饥饿对小菜蛾幼虫抗寒性的影响。测定了在25°C和6°C下提供和不提供食物对不同龄期幼虫存活率的影响,结果表明:6°C下不管提供食物与否1龄和2龄幼虫均死亡;在提供食物的情况下16%的3龄幼虫和43%的4龄幼虫能够正常化蛹,但不提供食物幼虫均死亡。测定了低温处理前幼虫饥饿状态、处理温度及暴露时间对不同龄期幼虫存活率的影响,结果发现:1)在-5°C和-10°C下,不同龄期的幼虫若低温处理前提供食物,存活率均高于饥饿幼虫;2)在0°C不同暴露时间下,若处理前提供食物,2龄幼虫存活率高于饥饿幼虫,3龄和4龄低于饥饿幼虫。3测定了阶段性取食对小菜蛾低温存活的影响,试验结果如下:1)在0°C和5°C下暴露4d时,2,3,4龄有阶段性取食的幼虫存活率高于无阶段性取食幼虫;2)在-5°C,0°C和5°C下暴露6d时,2,3龄有阶段性取食的幼虫存活高于无取食幼虫,在-5°C下4龄有阶段性取食幼虫存活低于无取食幼虫,其它温度下存活情况与2,3龄幼虫相似;3)幼虫存活率随着温度的降低和暴露时间的延长而降低。4测定了春季寒潮对小菜蛾生命参数的影响。模拟武汉春季寒潮,将20°C饲养的4龄幼虫和刚羽化成虫置于1°C,4°C和7°C下暴露3d和6d,结果发现1)幼虫经历低温后,存活率无显著变化;幼虫发育至蛹所需时间延长,而且发育时间随温度降低而增加;在低温下蛹重随温度升高而增加;成虫产卵量增加。2)成虫经历低温后寿命延长,繁殖力下降。
[Abstract]:Plutella xylostella is an important pest in cruciferous vegetables. There has been no clear conclusion on overwintering in China. The overwintering status and geographical distribution of overwintering moth are not clear. This paper intends to explore the overwintering situation of Plutella xylostella from the point of view of low temperature and feeding. The effects of low temperature and food on the survival of Plutella xylostella were studied in the following four aspects: to determine the low temperature threshold for the larva of Plutella xylostella to stop and start feeding, to determine the cold resistance of the larvae of Plutella xylostella under different feeding conditions; The effects of stage feeding on the survival of Plutella xylostella in winter and the changes of life parameters of Plutella xylostella under the cold wave in spring were determined. The following results were obtained: 1. The low temperature threshold for the larvae of Plutella xylostella to stop and start feeding was determined. The number of larva feeding behavior was recorded at constant temperature of 1-13 掳C for 4 h. The results showed that the 2nd instar larvae stopped feeding at 2 掳C and the 4th instar larvae stopped feeding at 1 掳C. The temperature was decreased from 20 掳C to -9 掳C at 0.2 掳C / min, and increased to 20 掳C at the rate of 0.2 掳C / min after 15 minutes of equilibrium. The feeding temperature of larva stopped feeding and the beginning of feeding temperature during heating were measured. The results showed that the stopping feeding temperature of the third instar larvae was 4.7 掳C, the beginning feeding temperature of 12.2 掳C.4 larvae was 4.6 掳C, and the starting feeding temperature was 12.6 掳C.2. The effects of low temperature and starvation on the cold resistance of Plutella xylostella larvae were determined at 25 掳C and 12.6 掳C.2, respectively. Effects of feeding and non-feeding at 6 掳C on the survival rate of larvae of different ages, The results showed that both the 1st and 2nd instar larvae died at 6 掳C, and the 3rd instar larvae of 16% and the 4th instar larvae of 43% larvae could pupate normally under the condition of feeding. The effects of temperature and exposure time on the survival rate of larvae of different ages were determined. The results showed that: 1) at -5 掳C and -10 掳C. The survival rate of larva of different ages was higher than that of starved larva at 0 掳C at different exposure time, if the larvae of different ages provided food before low temperature treatment, the survival rate was higher than that of starved larva. If the survival rate of the 2nd instar larvae was higher than that of the third instar larvae and the 4th instar larvae were lower than that of the starved larvae before treatment, the effects of periodic feeding on the low temperature survival of Plutella xylostella were determined. The results were as follows: at 0 掳C and 5 掳C exposure for 4 days, the survival rate of the 4th instar larvae with stage feeding was higher than that of the non-stage feeding larvae (P < 0.05 掳C 0 掳C and 5 掳C for 6 d) the survival rate of the third instar larvae with stage feeding was higher than that of the non-feeding larvae after 6 days of exposure to 0 掳C and 5 掳C, and the survival rate of the third instar larvae was higher than that of the non-feeding larvae. At -5 掳C, the survival rate of the stage feeding larvae of the 4th instar was lower than that of the non-feeding larvae. Survival at other temperatures was similar to that of the 2nd instar larvae. The larval survival rate decreased with the decrease of temperature and exposure time. The effects of spring cold wave on the life parameters of Plutella xylostella were measured. The 4th instar larva and newly emerging adult larvae were exposed to 1 掳C 4 掳C and 7 掳C for 3 days and 6 days. The results showed that 1) the survival rate of larva had no significant change after low temperature, and the time needed for larval development to pupa was prolonged, and the development time increased with the decrease of temperature. Under low temperature, the pupae weight increased with the increase of temperature, and the spawning quantity of adult increased. 2) the longevity and fecundity of adult increased after low temperature.
【学位授予单位】：中国农业科学院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S433.4

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