Effects Of Short-term High Temperatures Ongrowth, Physiological And Biochemical Substances Of Mythimna Loreyi

Mythimna loreyi?Duponchel?is a closely related species of the Mythimna separata?Walker?.M.loreyi is often mixed with M.separata that harm corn and pose a threat to food production safety.Therefore,it is essential to control pests to ensure the safety of agricultural production.In recent years,global warming and extreme weather have occurred frequently.As a temperature-changing animal,the growth and development of M.loreyi is bound to be affected by extreme high temperature weather.In this paper,we investigated the effects of short-term extreme high temperature on the biological characteristics of M.loreyi and the activity of protective enzymes in vivo,and analyzed the related heat shock protein genes in order to explore the effects of high temperature in summer on the population dynamics of M.loreyi and the adaptability of high temperature provides a scientific basis for the prediction of M.loreyi.In this paper,the M.loreyi was treated at a high temperature?36°C,39°C,42°C?in the larval stage at 1st,3rd,and 5th instar larva under normal conditions until the end of adult spawning.The study found that after a short period of high temperature treatment in the larval stage,the survival rate of the 5th instar larvae was higher than that of the 1st and 3rd instar larvae.At 36-39°C,the developmental duration of larvae of 1st and 3rd instars shortened with the prolongation of treatment time.The trend reached 42°C and prolonged the performance,but 5th instar larvae of treatment at 36-42°C for 2-6 h,the developmental duration was significantly 3-5 days less than the control group.After pupal development duration,treatment with 1?3 instar larvae different temperature increased no significant effect.For the 5th instar larvae,after heat shock at 36°C and 39°C,the duration becomes longer with increasing temperature,and 42°C is shortened and then lengthened.Compared with the control,the emergence rate of the 5th instar larvae after treatment was lower than that of the 1st and 3rd instar larvae,and the overall rate was lower than that of the control.The 1st instar larvae treated at high temperature 36-42°C for 2-4 h,the survival rate of pupa period was not significantly different from the control,but the survival rate of pupa period decreased significantly after heat shock at 39°C and 42°C for 6 h.After 3th instar larvae of high temperature treatment,36°C,39°C with the treatment time prolonged,the survival rate decreased during pupa period,After 42°C high temperature treatment,there is a tendency to shorten and then lengthening.After treatment of 5th instar larvae at 36°C and 42°C,the survival rate in the pupa decreased with time,and the survival rate at 39°C in the pupa increased first and then decreased.At the 1st,3rd,and 5th instar larvae,the growth period of the adult and adult stages was not affected by the temperature increase and the length of treatment.Through the intrinsic rate of increase?r?,net reproductive rate?R₀?,mean generation time?T?,finite rate increase???parameter,etc.and construction of age-stage,two-sex life table.It is found that there is a generational overlap of M.loreyi,and the optimum temperature is 36°C for 4 h.When the external environmental conditions are not considered,it will increase by 1.121 times per day in a generational cycle of 38.12 d at an exponential growth rate of 0.115.The stress-resistant protective substance plays an important role in the resistance of M.loreyi to high temperatures.The high temperature heat shock 3rd and 5th instar larvae had higher protein content than the control group?CK?,and the 1st instar larvae had lower protein content than CK.Different temperatures,exposure times,treatment ages,and interactions affect the changes in SOD,POD,and CAT activities,but the length of exposure to CAT activity of 3rd instar larvae,and the CAT and POD activities of 5th instar larvae had no effect.The activity of SOD and POD in the 5th instar larvae of M.loreyi was lower than that in the 1st and 3rd instar,and the CAT activity of the 3rd and 5th instar larvae was smaller than that of the 1st instar larvae.Two heat shock protein genes?Hsp70,Hsp90?were cloned.The molecular masses of Hsp70 and Hsp90 genes were 71.51 kDa and 82.54 kDa,respectively,which were similar to those of other organisms Hsp70 and Hsp90.The C-terminus of Hsp70 has a sequence“EEVD”that binds to the molecular chaperone TPR domain;the C-terminus of Hsp90 has the sequence“MEEVD”,and molecular phylogenetic tree analysis shows that the M.loreyi is closely related to the oriental armyworm.This is consistent with traditional taxonomy.