摘要
以迁徙蚱蜢（Ｍｅｌａｎｏｐｌｕｓｓａｎｇｕｉｎｉｐｅｓ）经由口器取食摄入球孢白僵菌（Ｂｅａｕｖｅｒｉａｂａｓｉａｎａ）分生孢子的生测实验，证明其通过非体壁途径（即消化道）感染寄主的可能性。试虫通过摄食拌有分生孢子悬液的麦麸（５４．３～６０．０ｍｇ／虫）２４ｈ而接种，共６个剂量处理（１．６３×１０４～３．０８×１０６孢子／虫）加上空白对照（２５头／处理）。摄菌后以大麦苗单头盒装饲养（２１～２５℃，１５％～２０％Ｒ．Ｈ．，１６∶８Ｌ∶Ｄ），逐日观察记录并确诊感病死亡。所获数据经时间－剂量－死亡率模型分析，参数估计值均通过皮尔逊卡方和Ｈｏｓｍｅｒ－Ｌｅｍｅｓｈｏｗ检验，拟合良好。由模型参数确定随时间而递减的ｌｏｇ１０（ＬＤ５０）及其９５％置信区间，接种后第１０日为６．７２（６．４１～７．０３），第１５日为５．９１（５．７０～６．１１），第２０日为５．１５（４．９３～５．３８）。四个较高剂量处理的ＬＴ５０值分别为１８．１ｄ（１．７８×１０５孢子／虫）、１７．６ｄ（２．９７×１０５孢子／虫）、１２．４ｄ（１．４７×１０６孢子／虫）和１１．０ｄ（３．０８×１０６孢子／虫）。结果表明，试菌孢子可以通过寄主口器摄入而感染寄?
This paper presents bioassay data showing a non integument infection of the fungus Beauveria bassiana for the migratory grasshopper, Melanoplus sanguinipes, with chewing mouth parts. The newly emerged adults were fed individually for 24 h with a mixture of wheat bran and B. bassiana conidial suspension (54.3～60.0 mg per grasshopper). Six conidial dosages (1.63×10 4￣ 3.08 ×10 6 conidia per grasshopper) plus control were included in the bioassay with 25 grasshoppers treated at each dosage. After the ingestion of the conidia for inoculation, the grasshoppers were reared individually in venting plastic cages at 21￣25 ℃ and 15%￣20% R.H. with a photoperiod of 16∶8 (L∶D). Daily observation and records were made for individual death. Each cadaver, whenever found, was moved into a moist chamber to facilitate outgrowth of fungal mats for identifying the B. bassiana infection. The resulting data fit well to a novel time dose mortality model with significance of Pearson chi square test and Hosmer Lemeshow test. Based on parameters derived from the model, the values of log 10 (LD 50 ) and their 95% confidence intervals estimated were found to decrease with increasing days after the conidial ingestion, for example, 6.72 (6.41￣7.03) on day 10, 5.91 (5.70￣6.11) on day 15, and 5.15 (4.93￣5.38) on day 20. The values of LT 50 estimated were 18.1 d, 17.6 d, 12.4 d, and 11.0 d at the dosages of 1.78×10 5, 2.97×10 5, 1.47×10 6 , and 3.08×10 6 conidia per grasshopper, respectively. The results showed that the ingestion of the B. bassiana conidia by M. sanguinipes caused substantial infection. The author also discussed potential factors causing the differences in lethal rates due to different inoculation methods.
基金
国家杰出青年科学基金
国家自然科学基金
浙江省自然科学基金
关键词
球孢白僵菌
迁徒蚱蜢
口器摄入感染
死亡率模型
Beauveria bassiana
Melanoplus sanguinipes
conidial ingestion and infection
time dose mortality model
