Effects Of Short-term High Or Low Temperature Treatment On Biology And Metabolism Of Prodenia Litura Fabricius

Prodenia litura Fabricius is a kind of important agriculture pest which isworldwide, polyphagous and migratory. Since the middle of1980s, along with thefarming structure change and the impact of climate warming, the occurrence of P.litura aggravated year by year, from the past incidental and secondary pest rise torecurrent and disaster pest quickly. As a kind of poikilotherm, the insect has limitedcapacities to keep and adjust their temperatures. Ambient temperature determinestheir metabolic rates, which is the most important factor in affecting their lifeactivities, such as development, reproduction and survival. In the context of globalwarming, Further study of the influence of climate change, especially temperaturechange on insect’ life activities, has important theoretical significance and practicalsignificance for in-depth understanding of their adaptabilities to environmentalchange and population dynamics.In this study,3rd instar larvae of P. litura were exposed to35℃or13℃for8,16,24and32h, after which their development, survival and several biochemicalsubstances were investigated, and cold tolerance at-5℃for1.5h was observed. Themain results are as follows:1. The prepupal period of P. litura was shortened when treated at35℃. Whenexposed to35℃for8h,4th,5th and6th instars’ developmental duration of P. liturabecame long. When treated with35℃for24and32h,3rd,4th and6th instars’developmental duration of P. litura got short. When exposed to13℃,3th～6thinstars’ developmental duration of P. litura was extended significantly.2. High-temperature treatment at different time reduced3th～5th instars’survival rate. The survival rate of3th～6th instars all reduced when exposed to13℃.Compared with normal feeding temperature, The survival rates were about93%、79%、79%、71%and73%、72%、59%、52%of control, The pupation rate were about98%、83%、88%、78%and71%、59%、63%、48%of control when exposed to35℃and13℃for8,16,24,32h. Above all,13℃low temperature brought greater harm than35℃high temperature.3. The survival rates of P. litura after shocked at-5℃immediately or exposed tohigh (35℃) or low (13℃) temperature before shock were different. The coldtolerance of P. litura was significantly or extremely significantly improved afterexposed to35℃or13℃for8h before shock, the survival rates of which were1.15and1.29times of shocked immediately. The cold tolerance of P. litura were extremelysignificantly decreased after exposed to35℃for24and32h before shock, thesurvival rates of which were66.66%and66.23%of shocked immediately. The coldtolerance of P. litura were significantly or extremely significantly decreased afterexposed to13℃for24and32h, the survival rates of which were83.33%and74.02%of shocked immediately..4. Both Soluble protein content and triglyceride content in3rd instar larvae of P.litura were declined after high or low temperature treatment. Content of soluble sugarimproved extremely significantly after exposed to35℃for24h, while decreasedsignificantly after exposed to13℃for24h. Trehalose content declined after exposedto35℃for16,24and32h, but raised after treating at13℃for8,16and32h. Bothhigh and low temperature could improve TRE activity. POD and CAT activities of3rdinstar larvae of P. litura were improved when treated at high temperature. SODactivity of P. litura was improved after exposed to low temperature.The results indicated that short-term high or low temperature treatment made acertain effect on biology and metabolism of P. litura. Although short-term high or lowtemperature treatment improved the cold resistance of P. litura in a certain extent,they made unfavorable effects on the development and survival of P. litura. Theresults in this paper will provide the foundations for studying the relationship betweenP. litura and environmental change.