Colony success of the bumble bee, Bombus terrestris, in relation to infections by two protozoan parasites, Crithidia bombi and Nosema bombi
Colony success of the bumble bee, Bombus terrestris, in relation to infections by two protozoan parasites, Crithidia bombi and Nosema bombi
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DOI：
10.1007/s000400050139
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发表时间：
1999-01-01
期刊：
影响因子：
1.3
通讯作者：
Schmid-Hempel, P
中科院分区：
文献类型：
--
作者：
Imhoof, B;Schmid-Hempel, P
大黄蜂Crithidia bombi是大黄蜂的一种普遍的内寄生虫，它在宿主大黄蜂Bombus terrestris的殖民地内水平和垂直传播，并传播给下一代。在实验室培养的菌落转移到田间之前，通过实验感染或不感染标准接种剂，本研究旨在评估自然条件下炸弹梭菌的毒力水平。然而，一个意想不到的发现是自然种群感染的大量季节性增加，因此，一旦暴露于该领域，所有殖民地都迅速被感染。平均而言，实验感染的菌落在暴露后9.5天出现感染阳性迹象，与未处理菌落的11.7天没有区别。因此，毫不奇怪，在两个实验组之间，在衡量群体成功的指标上没有发现显著差异，比如雄性和年轻的蚁后的产量或有性繁殖的出现时间。总体而言，炸弹虫显示出较低的毒力水平，这符合最近寄生虫水平和垂直传播率相关的模型。另一方面，有性繁殖的数量取决于繁殖能够持续多久。因此，早期的群体和那些第一窝大、最大规模大的群体处于优势地位。此外，还发生了强烈的场地效应。此外，许多菌落自然感染了小孢子虫。这种感染与实验治疗或菌落大小无关，但与有性繁殖的增加有关，尤其是雄性。
Crithidia bombi is a prevalent endoparasite of bumblebees that is transmitted both horizontally between and vertically within colonies of its host, the bumble bee Bombus terrestris, and to the next generation. By experimentally infecting or not infecting laboratory-raised colonies with a standard inoculum before their transfer to the field this study was aimed at evaluating the level of virulence of C. bombi under natural conditions. However, an unexpected finding was a substantial and seasonal increase in infections of natural populations, such that all colonies quickly became infected once exposed to the field. On average, experimentally infected colonies showed positive signs of infection 9.5 days after being exposed, not different from the 11.7 days in untreated colonies. Not surprisingly therefore, no significant differences between the two experimental groups in measures of colony success, such as male and young queen production or time of emergence of sexuals, were found. Overall though, C. bombi showed low levels of virulence which fits recent models for parasites with correlated horizontal and vertical transmission rates. On the other hand, the number of sexuals produced depended on the length of time over which reproduction could be sustained. Thus, early colonies and those with large first brood and large maximum size were at an advantage. Also, strong effects of site occurred. In addition, many colonies became naturally infected with the microsporidian Nosema bombi. Such infections were not associated with experimental treatment or colony size, but correlated with an increased production of sexuals, particularly males.