桉树枝瘿姬小蜂的耐寒性测定

桉树枝瘿姬小蜂Leptocybe invasa Fisher&LaSalle是一种新入侵的检疫性有害生物,为了明确其对极端低温的耐受性,以了解其适生范围,测定了桉树枝瘿姬小蜂幼虫、蛹、成虫及不同地区、不同寄主条件下雌雄成虫以及广东、广西、海南3省6地越冬幼虫12—3月的过冷却点和冰点。结果表明,不同虫态的过冷却点和冰点由低到高顺序为:蛹<幼虫<成虫。蛹的过冷却点和冰点分别为(-24.93±0.10)℃、(-22.81±0.14)℃,成虫的过冷却点和冰点为(-20.93±0.24)℃和(-17.33±0.27)℃。随着纬度的升高,桉树枝瘿姬小蜂的过冷却点和冰点都呈现降低的趋势。海南地区不同寄主桉树枝瘿姬小蜂过冷却点从低到高的顺序排列为:湛-201<小叶桉<广林9号。在12—3月,桉树枝瘿姬小蜂的越冬幼虫过冷却点和冰点随着环境温度的升高而升高,以广东广州地区1月份的越冬幼虫过冷却点和冰点为最低,其数值分别为(-25.44±0.17)℃和(-24.04±0.21)℃,个体过冷却点的最低值为-26.9℃。由实验结果可知,桉树枝瘿姬小蜂蛹和幼虫的耐寒力最强,以幼虫和蛹越冬。地区、寄主、温度对其耐寒力均有显著的影响,而且其有向现疫区以北的区域扩散的潜能。

Extreme low temperature tolerance of Leptocybe invasa

Leptocybe invasa Fisher ＆ La Salle is a new, quarantinable, invasive species. In order to clarify the extreme low temperature tolerance and potential range of this pest we measured the supercooling and freeezing points of all life stages except the egg. Adult L. invasa live at different latitudes and have varied hosts. The larvae overwinter in three southern Chinese provinces from December to March. The relative supercooling and freezing points of three life stages was pupa 〈 larvae 〈 adult. The supercooling and freezing points of pupae were （ - 24.93± 0.05） ℃ and （ - 22. 81 ± 0. 02）℃, respectively, and the supercooling and freezing points of adults were （ - 20.93 ±0. 27 ）℃and （ - 17.33 ± 0.17）℃ , respectively. Supercooling and freezing points decreased with increasing latitude. The relative supercooling and freezing points of L. invasa on different hosts in Hainan Province were Zhan-201 〈 Eucalyptus exserta 〈 Guanglin nine. Supercooling and freezing points of L. invasa are rising with increasing environmental temperatures. The lowest supercooling and freezing points of overwintering larvae, （ - 25.44±0.17 ）℃ and （ - 24.04 ± 0.21 ）℃, were recorded in Guangzhou city in January when the temperature was the lowest in four months. The lowest recorded supercooling point of an individual was - 26.9℃. Our results reveal stronger cold hardiness in the pupa and egg stages than in larvae or adults. Latitude, host and temperature have an appreciable impact on cold hardiness. The results suggest that this pest has the potential of spreading further north.