Preliminary Studies On The Basis Of Biological And Hysiological Of Thermal Tolerance Of Asecodes Hispinarum Bou(?)ek

The coconut leaf beetle Brontispa longissima (Gestro) is an important invasion alien pest of coconut palms. Asecodes hispinarum Boucek is a parasitoid of B. longissima larva. It was introduced successfully into Vietnam, Maldives,Thailand, Cambodia and China, and has done an important role in the controlling of Brontispa longissima. The biological, ecological and physiological mechanisms of thermal tolerance of A.hispinarum were further systematically preliminary studied in this article based on the previous findings. The main results are summarized as follows:1 The biological of thermal tolerance of A. hispinarum1.1 The effects of heat stress on survival of A. hispinarumThe survivals of larvas and pupas of A. hispinarum were studied after them exposed to 30℃,33℃,36℃,39℃and 42℃for 8 h while adults exposed for 2 h. The results showed that the survival rates of A. hispinarum at the three tested developmental stages decreased with the increase of temperature during the same exposure times. The larvas of A. hispinarum all died after exposed to 42℃for 8 h, and the survival rates of pupas were just 36.67%.The survivals of larvas and pupas of A. hispinarum were studied after them exposed to 39℃for 2 h,4h,8 h,12 h and 16 h, while the adults exposed to 39℃for 1 h,2h,3h,4 h and 5 h.The results indicated that the survival rates of A.hispinarum at the three tested developmental stages decreased with the prolong of heat tress times in 39℃.The survival rates were 33.33% and 56.67% respectively after larvas and pupas of A.hispinarum exposed to 39℃for 16 h, the survival rates were 2.67% after adults of A.hispinarum exposed to 39℃for 5 h.Fitting the equation between survival rates of larvas, pupas and temperature or treatment time. It was found that they were in line with linear regression relationship. The lethal temperature of larvas and pupas were 36.78℃and 40.32℃respectively after larvas and pupas exposed for 8 h. The lethal time of larvas and pupas were 10.41 h and 19.34 h respectively after them exposed to 39℃.The longevity of adults of A.hispinarum was significantly affected in different high temperatures. The longevity of famaie and male adults decreased with the increase of temperature, and the longevity of famale adults were higher than male adults in the same conditions.The female adults of A.hispinarum survival only for 3.53 h in 42℃.The survival rates of female adults were significantly higher than male adults in the same treating conditions. Fitting the equation between survival rates of adults and temperature or treatment time. It was found that they were in line with linear regression relationship. The lethal temperature of female adults were higher than male adults after them exposed for 2 h. The gap was 1.08℃between each other. The lethal time of female adults was 3.10 h after them exposed to 39℃.The gap was 0.4 h and 0.67 h respectively between each other.1.2 The effects of heat stress on the development and fecundity of A.hispinarumThe development and fecundity of A.hispinarum were studied after eggs,larvas and pupas exposed to 30℃,33℃,36℃,39℃and 42℃for 8 h. The results indicated that the development duration prolonged with the increase of temperature,and the development duration extended to 20.46 d after pupas of A.hispinarum exposed to 42℃for 8 h. The number of wasp offsprings per host and rate of adult emergence decreased with the increase of temperature, and the number of wasp offsprings per host was 0 after eggs and larvas of A.hispinarum exposed to 42℃for 8 h. The number of wasp offsprings per host decreased to 34.83 significantly after pupas exposed to 42℃for 8 h. Besides, the female ratio was significantly affected in different high temperatures.The female ratio increased significantly after eggs and larvas of A.hispinarum exposed to 39℃for 8 h. The female ratio was not significantly compared with normal after pupas exposed within the range of 33℃-39℃for 8 h, but the female ratio arised to 94.31% after exposed to 42℃for 8 h.The development and fecundity of A.hispinarum were studied after adults exposed to 30℃,33℃,36℃,39℃and 42℃for 2 h. The results indicated that the development duration of the next generation of A.hispinarum prolonged with the increase of temperature, and the development duration of the next generation of A.hispinarum extended 2.29 d after exposed to 42℃for 2 h compared with normal.The parasitism rate and the rate of adult emergence of nex generation decreased significantly with the increase of temperature. Fitting the equation between the rate of adult emergence of nex generation and temperature. It was found that they were in line with linear regression relationship. The number of wasp offsprings per host and female ratio of next generation were significantly affected after exposed to above 39℃, The number of wasp offsprings per host and female ratio of next generation decreased with the increase of temperature, and the female ratio decreased to 75.31% after exposed to 42℃for 2 h.The development and fecundity of A.hispinarum were studied after them exposed to 39℃for 2 h,4h,8 h,12 h and 16 h. The results indicated that the development duration prolonged with the increase of time.The eggs stopped development, and the development duration extended 3.28 d after lavars exposed to 39℃for 16 h. The development duration extended to 19.59 d after pupas exposed to 39℃for 16 h. The number of wasp offsprings per host and the rate of adult emergence decreased significantly as the time prolonged. The number of wasp offsprings per host was 0 after eggs exposed to 39℃for 16 h. The number of wasp offsprings per host decreased to 30.83 and 45.59 from 79.96 in the normal, and the rate of adult emergence decreased to 47.50% and 58.49% respectively. The female ratio increased significantly after eggs and larvas exposed to 39℃for 8 h, and the female ratio arrived to 94.90% and 94.42% respectively after eggs and larvas exposed for 12 h. The female ratio arised a liitile, but not significantly after pupas exposed for different times.The development and fecundity of A. hispinarum were studied after adults exposed to 39℃for 1 h,2h,3 h,4 h and 5 h. The results indicated that the development duration of the next generation of A. hispinarum prolonged with the increase of temperature, the development duration of the next generation of A. hispinarum extended 2.46 d after exposed to 39℃for 5h compared with normal. Besides, the number of wasp offsprings per host and the rate of adult emergence of next generation decreased as the time prolonged. The number of wasp offsprings per host of next generation cut down 54.6 compared with normal after adults exposed to 39℃for 5 h, and the rate of adult emergence was just 37.5%. The parasitism rate and the female ratio were affected after adults exposed for different times, The parasitism rate and the female ratio decreased as the time prolonged, the parasitism rate was just 8.82% when dults exposed to 39℃for 5 h.The population parameters of egg,lavar and pupa of A. hispinarum exposed to different temperatures showed that the order of rm was:26℃>30℃>33℃>36℃>39℃>42℃. The Ro was 0 after egg and lavar exposed to 42℃. It was showed that A.hispinarum have no effective ability of fecundity.The rm decreased significantly with the increase of temperature after four tested developmental stages exposed to high temperatures. The egg declined more quickly than lavar, the lavar declined more quickly than pupa. The thermal sensitivity of different development stages of A. hispinarum were greatly affected after exposed to high temperatures, the heat tolerance order was:pupa>larva>egg.2. The hysiological of thermal tolerance of A. hispinarumBy using spectrophotometric method, the activities of protective enzymes in the lavars,pupas and adults of A. hispinarum were determined after them exposed to 30℃,33℃,36℃,39℃and 42℃.After larvas and pupas of A.hispinarum exposed for 8 h, the results showed that the enzyme activity ratio on treatment proup and control group increased firstly and decreased later, and the enzyme activity of the treatment proup was higher than control group. The maximum activity of CAT in the treatment proup was at 39℃heat-shock, which were 2.28 and 2.07 times higher than those in the control group respectively.The enzyme activity ratio increased significantly after adults of A. hispinarum exposed to 33℃for 2h. The enzyme activity ratio arrived to top after exposed to 36℃.The ratio of activity of SOD arrived to top after larvas, pupas and adults of A. hispinarum exposed to 36℃. The enzyme activity inhibtied after temperature increased to above 36℃.The activity of POD was significantly different after larvas,pupas and adults of A.hispinarum exposed to different temperatures. The activity of POD was inhibted when larvas and pupas of A.hispinarum exposed to 33℃for 8h. The enzyme activity ratio increased with the increase of temperature, and the maximum activity of CAT in the treatment proup were at 36℃and 39℃heat-shock, which were 1.92 and 1.6 times higher than those in the control group respectively.The enzyme activity ratio decreased after adults exposed to 33℃for 2 h,then the enzyme activity ratio starded to increase after temperature increased to 36℃.