Effect Of Extreme High Temperature On Growth And Development Of Plutella Xylostella(L.)

In recent years,extreme high temperature events occur frequently in global warming.As a small variable temperature animal,insects are greatly affected by natural environmental factors.As one of the natural environmental factors,temperature has a significant impact on the propagation,growth,survival,longevity and oviposition of insects,and then affects the occurrence regularity of insects,distribution range and population size.However,its unique ecological significance has not been noticed.Therefore,research of high temperature on reproduction,survival,growth and development of diamondback moth,Plutella xylostella,a pest of cruciferous vegetables,have been studied in this paper.The main contents and results are as follows:The extreme thermal tolerance(CTmax)of larvae and adultsof P.xylostella population reared under 25?were measured.The results showed that the larvae pretreatment,adult sex and interaction between these two factors had no significant effect on the extreme thermal tolerance of diamondback moth(P.xylostella)larvae and adults through the extreme short-termthermal tolerance test.There was no significant difference in the mean CTmax of P.xylostella at different developmental stages.While the interaction between larval pretreatment and developmental stage significantly affected the extreme thermal tolerance of P.xylostella.Pretreatment of larvae had no significant effect on the CTmax of adults,while larval pretreatment significantly increased the thermal tolerance of P.xylostella larvae.Without larval pretreatment,the thermal tolerance of the adult diamondback moth is stronger than that of the larva.The persistent thermal tolerance of the 1st and 3rd instar larvae of P.xylostella 25?population was measured,we found that the survival rate of P.xylostella decreased significantly with the increase of the duration of high temperature.The survival of the early stage of life is worse than that of the later stage,and this difference is especially evident at higher temperatures.The survival under long-term high temperature stress is a combination of immediate and subsequent survival,and the immediate survival and subsequent survival may be different at different stages of life.The life cycle characters of P.xylostella population reared at high,medium and low temperature were measured.The hatching rate of P.xylostella population decreased under high temperature,while the average egg hatching rate was up to 79.4%.After endured high temperature,the developmental period of the eggs of P.xylostella significantly shortened,and low temperature could prolong the life span of P.xylostella population.Low temperature had no obvious effect on pupal weight,while increased pupal weight at high temperature.The longevity of males is slightly longer than that of females.Temperature plays an important role in spawning of P.xylostella.With the increase of temperature,the number of eggs laid by female P.xylostella decreased.Low temperature is not conducive to mating of P.xylostella,of which 18 ? P.xylostella stopped mating.The results provide scientific guidance for the integrated control of P.xylostella under high temperature in summer,and provide theoretical basis for the study of high temperature phenotypic plasticity of P.xylostella.