松墨天牛取食期间传播松材线虫的特性

【目的】系统研究松墨天牛(Monochamus alternatus)羽化后传播松材线虫(Bursaphelenchus xylophilus)的起始和结束日期、传播松材线虫的数量及百分比、传播松材线虫数量的时间动态变化规律,以及天牛成虫携带松材线虫的数量、取食数量、寿命、传播松材线虫时长与数量之间的关系等,为松材线虫病的研究和防治提供理论参考。【方法】于松墨天牛羽化前在松材线虫病疫区收集松材线虫病病死马尾松疫木,将疫木截为1.0~1.5 m长木段并置于室外大养虫笼(2.0 m × 2.0 m × 2.0 m)中,在天牛羽化期间逐日收集新羽化的松墨天牛,并用1年生新鲜马尾松枝条(直径1~2 cm,长度25~30 cm)于室外养虫笼(0.5 m × 0.5 m × 0.5 m)中单只喂养。每3天更换1次枝条,并用测量纸测量天牛在枝条上的取食刻痕面积记为取食天牛数量,然后将枝条剪碎采用贝尔曼漏斗法分离天牛取食枝条中的松材线虫;统计每头松墨天牛每3天传播松材线虫的数量及传播松材线虫的起止日期。天牛死亡后将天牛剪碎用贝尔曼漏斗法分离天牛体内残余松材线虫,统计松墨天牛成虫寿命及携带松材线虫的数量。【结果】羽化初期传播松材线虫的天牛比例较低仅为16.7%,大多数(77.8%)松墨天牛集中在羽化后的7~12 d开始传播松材线虫。大多数(88.8%)松墨天牛在羽化后的16~30 d结束松材线虫传播。松墨天牛羽化初期传播线虫的数量较少,但1周后传播线虫数量迅速上升,并在天牛羽化后的12和24 d出现传播松材线虫的两次高峰;松墨天牛羽化1个月后维持在较低传播水平继续传播松材线虫至结束。松墨天牛携带松材线虫的平均数量为(4 303.3±7 399)条。大多数(94.4%)松墨天牛未能将携带的松材线虫全部传播到松枝上,平均传播松材线虫数量为(490.7±611.6)条,传播比例为29.8%。松墨天牛传播松材线虫的平均时长为(15.4±7.8) d。松墨天牛平均寿命为(37.8±5.6) d。【结论】雌雄松墨天牛羽化后起始传播松材线虫的日期无显著差异,但结束传播松材线虫的日期存在显著差异;松墨天牛起始传播松材线虫的日期较为集中,但结束传播松材线虫的日期较为分散,天牛传播松材线虫起止时间的特性可能与线虫在天牛体内的生理变化有关。雌雄天牛携带和传播松材线虫的数量无显著差异。雌雄天牛传播松材线虫数量的时间动态变化规律无显著差异。松墨天牛携带的线虫数量越多、传播松材线虫持续时间越长,则传播松材线虫的数量越多。松墨天牛传播松材线虫的时长不受天牛寿命以及天牛携带线虫数量的影响。松墨天牛传播线虫的数量与天牛寿命无关,但是松材线虫对天牛寿命有一定的负面影响。松墨天牛羽化后的取食量在整个成虫阶段一直保持较高水平,但无明显规律性,天牛取食数量与线虫传播量无相关性。

Transmission of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) through feeding activity of Monochamus alternatus (Coleoptera: Cerambycidae)

【Objective】Systematic investigation of the start and end dates of pine wood nematode (PWN, Bursaphelenchus xylophilu) transmission following the emergence of long-horned beetle(Monochamus alternatus), the number and percentage of PWN transmitted, the temporal dynamics of PWN transmission, and the relationships between the number of PWN carried by adult beetle, the food intake and the longevity of M. alternatus, the duration of PWN transmission by M. alternatus and the number of PWN transmission. 【Method】Dead specimens of Pinus massoniana were collected in epidemic area of pine wilt disease before the emergence of M. alternatus. The specimens were cut into logs (1.0-1.5 m in length), and maintained in a large field cage (2.0 m × 2.0 m × 2.0 m) and kept outdoors. The M. alternatus adults were collected daily during the period of adult beetle emergence from the logs and fed individually with 1-year-old fresh twigs (diameter: 1-2 cm. length: 25-30 cm) of P. massoniana in insect-rearing cages (0.5 m × 0.5 m × 0.5 m). Twigs were replaced every 3 days and measured the amount of food consumed by each M. alternatus. The PWNs were extracted by the Baermann funnel method and record the number of PWNs transmitted by M. alternatus. The M. alternatus were dissected after they died. The PWNs remaining within the adult insects were extracted by the Baermann funnel method and counted under a microscope. Record the longevity and PWN carrying capacity of M. alternatus.【Result】 Only 16.7% ofM. alternatus transmit PWN in the early stage of their emergence, and 77.8% of M. alternatus transmit PWNs 7-12 days after their emergence. In addition, 88.8% of M. alternatus ended the transmission of PWNs 16-30 days after their emergence. The number of PWN transmitted was small in the early stage of the emergence of M. alternatus. However, the number of PWN transmitted increased rapidly one week after the emergence of M. alternatus. Two peaks of transmission occurred at 12 days and 24 days post the emergence of M. alternatus. The transmission of PWN continued at a low level one month after the emergence of M. alternatus until the end of transmission. On average, each of the M. alternatus carried (4 303.3 ± 7 399) and transmitted (490.7 ± 611.6) PWN. The 94.4% of M. alternatus could not transmit all PWNs to logs, and the proportion of PWN transmitted was 29.8%. The average duration of PWN transmission by was (15.4 ± 7.8) days. The mean longevity of M. alternatus was (37.8 ± 5.6) days. 【Conclusion】The date starting to transmit PWN was not significant between male and female M. alternatus after emergence, but there was a significant difference in the end of PWN transmission. The start date of the transmission of PWNs by M. alternatus was concentrated, but the end date of the transmission of PWNs was dispersed. The characteristics of the start-stop time of PWN transmission by M. alternatus may be related to the physiological changes of the PWN in adults beetle, which needs to be further studied. There was no significant difference in the number of PWN carried and transmitted between male and female M. alternatus. There was no significant difference between male and female M. alternatus in the temporal dynamics of transmission of PWN. The longer the duration of PWN transmission and larger the number of PWN carried by eachM. alternatus, the more PWN was transmitted. The duration of PWN transmission was little affected by the longevity of the M. alternatus or the number of PWN carried. There was no relationship between the longevity of M. alternatus and number of PWN transmitted; but PWN had a weak and not significant negative effect on the lifespan of the adult beetle. After emergence, the amount of food consumed by M. alternatus maintained at a high level throughout the adult stage without obvious regularity; there was no relationship detected between the amount of food consumed and the number of PWN transmitted.