温度对发头裸腹溞生殖能力的影响

EFFECT OF THE TEMPERATURE ON THE REPRODUCTION CAPACITY OF MOINA IRRASA

在实验室培养条件下饲以充足食物,对不同温度下发头裸腹溞(Moinairrasa)的最大生殖能力进行了研究。结果表明:在5个不同温度((15±1)℃、(20±1)℃、(25±1)℃、(30±1)℃、(35±1)℃)条件下,发头裸腹溞最大生殖个体的体长可达1.93mm;性成熟所需的时间分别为:4.0d、2.36d、1.40d、1.31d和1.0d;各成龄期平均产仔量为:(24.78±4.29)个、(19.1±2.42)个、(26.25±5.71)个、(27.62±2.72)个和(19.47±3.29)个;平均累计产仔量则为:(87±26)个、(159±39.5)个、(239±21.9)个、(130.9±36.1)个、(81.6±17.0)个。发头裸腹溞的最适生殖温度在25—30℃之间,25℃时其累计生殖量最大,为(239±21.9)个。生殖的极限温度最高约为38℃,生活的临界温度最高在40℃。温度低于11℃时发头裸腹溞已不适合进行孤雌生殖诓煌露忍跫?发头裸腹溞性成熟所需的时间与水温的关系可用回归方程表示为:h=7231.4t-1.6167。本文亦对同属中几个相近种的生殖能力及相关生物学现象进行了探讨。

Samples of the Moina irrasa were collected in Gudang irrigation canal, a small canal for agriculture in Hangzhou, Zhejiang Province （30°17′N, 120°07′E）, and were given abundant food （fed with Scenedesmus obliquus at about the density of 3 × 10^5 cells /mL）. The juveniles from the female parent were isolated and cultured in different temperatures （ （ 15 ±1 ）℃ , （20 ±1 ）℃ , （25 ±1 ）℃ , （30 ±1 ）℃ , （35 ±1 ）℃） respectively. The experiment was carried out under a constant light regime of 12h light： 12h dark. Observed four times each day, the body length was measured,the instars duration and the brood size were recorded. Mature age of M. irrasa was related to water temperature in inverse ratio,the relationship between mature age and wa- ter temperature at 15--35℃ could be expressed by formula： h = 7231.4t-16167 ,and the mature age was delayed to 19.3d visibly at （11 ±1 ）℃. It was found that M. irrasa has 3 pre-aduh instars,3--8 adult instars at 15℃ ,30℃ and 35℃ respectively, 12--13 adult instars at 20 and 25℃. The mean longevity of individuals was estimated to be 13.6 ＋ 2. 1 days or 12.2 ＋ 3.1 instars at 25℃ and 36.2 ± 5.2 days or 6.8 ± 3. 1 instars at 15℃. At 15--35℃ ,the lower temperature,the more brood size of the first adult instars. The maximum egg production of the first adult instars was 19.8±1.7 at 15 ± 1℃. From the 4th instars （ part of individual from the 5＇h at （ 15 ±1 ） ℃ ） ,M. irrasa began to reproduce,the egg production increased with the instars,but began to declined after the maximum egg production appeared. The experiment showed,the instars that reached the most fecundity were different in each temperature. Usually,the maximum brood size was observed from the third to the fifth adult instars. The body length was 1.12-- 1.45mm at （15±1 ） ℃,1.06--1.47mm at （30±1 ） ℃ and 1.05--1.43mm at （30±1 ） ℃,the fecundity increased with the body length. The body length at （20 ±1 ） ℃ and （25 ±1 ） ℃ and the brood size were longer than the other temperatures. Under the condition of the 5 different temperatures （15℃,20℃ ,25℃ ,30℃ and 35℃ ） , the maximum size reached 1.93mm at 25℃, From juvenile stages to adult instars at 5 different temperatures, it needed 4d,2.36d, 1.4d, 1.31 d and 1.00d respectively. The average number of egg production per adult was 24.78 ± 4.29,19.1 ± 2.42,26.25 _＋ 5.71,27.62 ±2.72 and 19.47 ± 3.29;and the average individual cumulative egg production was 87 ± 26,159 ± 39.5,239 ± 21.9, 130.9± 36.1,81.6 ± 17.0,respectively. To M. irrasa, the most appropriate temperature for production was during of 25-- 30℃ and the maximum individual cumulative at 25℃ ,which egg production was 239 ±21.9. The average cumulative number of egg production was less than 100 at （ 15 ± 1 ） ℃ and （35 ± 1 ） ℃ ,only a few of individual reach to 151 and 117. It showed that although M. irrasa could produce, it could not reach to the maximum fecundi- ty in this case. The experiment showed that the temperature＇ s upper limited for M. irrasa at 38℃ for bear and at 40℃ for living. On the condition of 11 ℃ ,the M. irrasa were not suitable for production in their parthenogenetic generation. Reproduction capacity and biological phenomenon in several close species to M. irrasa in Genus Moina were also discussed in present.