| Global climate warming has become an irreversible trend.The impact of climate warming on insects has always been a hot topic in scientific research.The rising temperature resulted in accelerated growth and development,shortened generation period,smaller adults body size and declined fertility of insects.However,previous studies have mainly focused on the effects of constant heat or short heat shocks on insects.Climate warming is not only manifested by the increase of global average temperature,but also by the increasing intensity,duration and frequency of extreme high temperature weather in local areas,which are termed as periodic repeated high temperature.The periodic repeated high temperature usually includes two patterns: the different frequency and the different duration.Bemisia tabaci is one of the most serious invasive pests in the world.It has caused increasing economic losses every year.However,the control of this pest is facing some problems in China.On the one hand,because of excessive use of chemical control,serious resistance to several pesticides has quickly developed in B.tabaci,and at the same time,environmental security problems have been raised.On the other hand,the local natural enemies,including predators and parasitoids,proved to be inefficient to control this pest.Under this background,we introduced a dominant parasitic wasp of B.tabaci from Pakistan,Eretmocerus hayati.It was able to parasitize and feed on all nymphal stages of B.tabaci,with a high parasitism rate.However,the performance of this parasitoid under repeated periodic high temperature conditions is still unknown.So,the aim of this study is to demonstrate how recurrent high temperatures affect phenotypic plasticity,life-cycle characteristics,adaptability,heat resistance and control efficacy of Er.hayati? To what extend? The main results and conclusions were as follows:1.The fitness of Er.hayati were evaluated under different high temperature models via the study of two-sex life table.It was found that enhanced high temperature treatment intensity resulted in shortened pre-adult and longevity of females and males of Er.hayati,relative to the constant 26℃.Under the same temperature model,the longevity of female was longer than that of male.The high-frequency and long-duration treatment at 38 or 40℃ resulted in the fecundity,life expectancy and population parameters of Er.hayati were higher than those under lowfrequency and short-duration high temperature treatments.So,the suitable high temperature increases the fecundity of parasitic wasps.2.The body size and ova occurrence of Er.hayati under the periodic repeated high temperature were studied.Mature ova of adult female Er.hayati increased gradually with time.The number of mature ova decreased significantly with the increase of temperature.Within 48 h of emergence at 36℃ for 2h,the mature ova of the ovary parasitic wasps was higher under the high-frequency group than it under the low-frequency group,and generally in the other groups,the mature ova under low-frequency were more than that under high-frequency,and the shortterm groups were more than the long-term groups.The female adult size of Er.hayati decreased with the increase of temperature and frequency,but there was no significant difference between frequencies or treatment durations.3.The expression of hsp70 and hsC70 in Er.hayati under the periodic repeated high temperature was determined.The expression of hsp70 was up-regulated by increasing temperature,frequency or treatment duration.The expression of hsC70 was generally downregulated by high temperature.Under the same conditions,the expression of hsp70 and hsC70 of Er.hayati pupae were generally higher than that in female adults. |
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