关键词: 光滑足距小蠹, 实验种群, 发育, 繁殖, 温度

Abstract: In order to illustrate the influences of temperature on development and reproduction of the ambrosia beetle Xylosandrus germanus, the adult females and larvae of the ambrosia beetle were fed with Acremonium kiliense and Ambrosiella hartigii, respectively, in Petri dishes, the adult females were reared on semi-artificial diet in glass tubes, and its development at six constant temperatures between 16 and 31℃ and its fecundity and sex ratio at five constant temperatures between 16 and 28℃ were studied in the laboratory, respectively. The results showed that the developmental duration for the immature stages and from the egg stage to adult emergence increased with the temperature within the range of 16 to 28℃, and the development duration at 16℃ was 3-4 times as long as that at 28℃; it, however, was prolonged at 31℃ except during the pupal stage. Developmental duration of the larva was the longest at all temperatures tested, and was more than half of that from the egg stage to adult emergence. The optimum temperature for the larval stage was 26.44℃. Temperature thresholds for development ranged from 11.0 ℃ (pupal stage) to 12.7℃ (egg to adult). The thermal constant was the lowest for the egg (61.5 degree-day, DD) and the highest for the larva (189.7 DD). Nearly 305 DD was required above the lower temperature threshold of 12.7℃ to complete the development from egg to adult. Survivorship from egg to adult increased from 53.3% at 16℃ to 68.3% at 25℃, and decreased from 35.0% at 28℃ to 3.3% at 31℃. The larvae almost failed to pupate at 31℃. When the adult females were reared on semi-artificial diet in glass tubes, the life fecundity averaged 114.3 to 121.5 offspring per female at 22-25℃, and was the highest at 25℃, almost 3 times that at 16℃ and two times that at 19℃ or 28℃. The female to male sex ratio was lowest (9.6∶1) at 16℃ and highest (23.3∶1) at 25℃, and above 19.0∶1 at the rest of all temperatures tested. The results suggest that temperature directly influences the development of X. germanus, and also influences the reproduction of X. germanus mostly by influencing growth and sporulation of the ambrosia fungi.

Key words: Xylosandrus germanus, experimental population, development, fecundity, temperature