摘要
为探究蜜蜂球囊菌Ascosphaera apis只侵染封盖前后蜜蜂幼虫的原因及相关侵染机制,本研究利用实验室饲养的意大利蜜蜂Apis mellifera ligustica幼虫,给其接种球囊菌孢子,探究不同接种量(0,1.0×102,1.0×103,1.0×104,1.0×105和1.0×106孢子/mL)、接种时期(3,4,5和6龄幼虫)以及28℃低温处理6h对蜜蜂球囊菌侵染的影响。同时对处于不同侵染阶段的蜜蜂幼虫做病理学切片,探究球囊菌侵染的过程。结果显示:球囊菌孢子接种量与蜜蜂的发病率密切相关(r=0.9883),蜜蜂幼虫对低于1.0×103孢子/mL的侵染有抗性,与不接孢子的对照组差异不显著(P>0.05)。蜜蜂不同龄期接种发病率的差异是因不同龄幼虫食量不同导致的摄入孢子剂量的不同引起的,28℃低温处理能够显著提高处于幼虫到蛹转化期蜜蜂的发病率(P<0.05),而对取食阶段的蜜蜂幼虫没有影响。病理学研究表明,在整个幼虫期,摄入的孢子因中肠没有氧气不生长,对幼虫没有致病性,幼虫的取食和发育过程正常,至幼虫期结束进入蛹期后,蜜蜂的中后肠接通,摄入的孢子伴随蜜蜂的蛹便进入后肠并在此迅速萌发生长,在1～2d内菌丝即突破体表,导致蜜蜂死亡。蜜蜂球囊菌选择营养物质储存最多而防御能力较低的幼虫到蛹转化期侵染,降低了侵染成本,提高成功率。该研究阐明了蜜蜂球囊菌侵染蜜蜂的机制,丰富了昆虫与病原菌之间相互作用的内容。
To explore why the fungus Ascosphaera apis only infects the honeybee stretched larvae some hours before and after sealing and the related infection mechanism, the inoculation experiments were carried out with different dosages of A. apis spores （0, 1.0 × 10^2, 1.0×10^3, 1.0 × 10^4, 1.0 × 10^5 and 1.0 ×10^6 spores/mL）, inoculation time （3rd, 4th, 5th and 6th instar larva） and low-temperature treatment of 28℃. Furthermore, larvae in different infection stages were sectioned to investigate the infection process of A. apis. The results showed that A. apis pathogenicity is dose-dependent, A. mellifera ligustica larvae could resist the infection of A. apis at the dosages lower than 1.0 × 10^3 spores/ mL and the corresponding infection rates at these dosages had no significant difference from the control （ P 〉 0. 05 ）. The differences of morbidity in different instars of larvae inoculated are due to the difference in spore dosage ingested by different instar larvae. Chilling treatment at the transformation stage significantly increased the infection （ P 〈 0.05 ）. In addition, pathologic section showed that the spores in the midgut could not grow due to lack of oxygen, unless they could arrive the hindgut accompanying with faeces. The mycelium in hindgut broke through the gut wall, massively proliferated in body cavity and finally outgrew from the cuticle. Larvae in transformation with the maximal nutrient substances stored and significantly decreased immunity provide A. apis the best opportunity to infect by increasing the possibility of success and decreasing the cost. Altogether, the present work provides a foundation to elucidate the mechanism of A. apis infection and the mechanisms of insect-pathogen interaction
出处
《昆虫学报》
CAS
CSCD
北大核心
2012年第7期790-797,共8页
Acta Entomologica Sinica
基金
福建省自然科学基金项目(2010J01060)
现代农业产业技术体系建设专项资金(CARS-45-KXJ7)
关键词
蜜蜂
蜜蜂球囊菌
意大利蜜蜂
侵染
孢子剂量
接种时期
致病性
Honeybee
Ascosphaera apis
Apis mellifera ligustica
infection
spore dosage
inoculationtime
pathogenicity
