暗孢耳霉侵染竹梢凸唇斑蚜的生物学特征及毒力测定

Infection Features and Bioassay of Aphid-Obligate Conidiobolus obscurus on the Bamboo Aphid Takecallis taiwanus

通过扫描电镜观察蚜科专化菌暗孢耳霉对竹梢凸唇斑蚜的侵染特征。孢子附着在蚜虫体表后可迅速萌发直接侵入虫体,24 h后即有蚜虫感病死亡。在寄主死亡6 h内,假囊状体先突破体壁,分生孢子梗随后出现,后者可通过产孢启动新一轮的侵染循环。毒力生物测定结果显示,暗孢耳霉对竹梢凸唇斑蚜具有高毒力。在高剂量接种浓度(192.6±20.3)个孢子·mm-2时,92.8%的接种蚜虫5天内死亡。经时间-剂量-死亡率模型分析,第5天的半致死浓度低至51.6个孢子·mm-2,半致死时间在接种浓度100个孢子·mm-2时仅为2.3天。

Bamboo forests are multi-function resources,which frequently suffer from bamboo aphid infestation. This study aimed to estimate the potential of the aphid-specific pathogen Conidiobolus obscurus on bamboo aphid biocontrol.Tthe fungal infection features on Takecallis taiwanus were observed by scanning electronic microscopy. Conidia adherent to the aphid cuticle could germinate rapidly to invade into host body. 24 h after inoculation,first cadavers appeared.Cystidia penetrated the cuticle in 6 h after host death,and followed by conidiophores,which sporulate for renewing next infection cycle. The result of multi-concentration bioassay showed that C. obscurus had high infectivity to T. taiwanus.After inoculated at high conidial concentration of（ 192. 6 ± 20. 3） conidia· mm^- 2,92. 8% aphids died in 5 days. The bioassay data were well fitted to the time-concentration-mortality model,and the lowest value of the median lethal concentration was computed as 51. 6 conidia·mm^- 2on day 5. Meanwhile,the median lethal time was computed as 2. 3days under the inoculation of 100 conidia· mm^- 2. All the results presented the promising potential of C. obscurus on bamboo aphid pest control.