蘇力菌以色列變種感染蚊類幼蟲之組織病理學研究

HISTOPATHOLOGICAL STUDIES OF MOSQUITO LARVAE INFECTED BY BACILLUS THURINGIENSIS VAR. ISRAELENSIS

康世昌(Shih-Chan Kang) ； 陳錦生(Chin-Seng Chen)

《中華昆蟲》 6卷1期 (1986/03) Pp. iv+39-56

https://doi.org/10.6660/TESFE.1986004

摘要

本試驗以臺灣三種常見之蚊子，白腹叢蚊（Armigeres subalbatus），熱帶家蚊（Culea quinquefasciatus）及埃及斑蚊（Aedes aegypti）之幼蟲材料，蘇力菌以色列變種（Bacillus thuringiensis var. israelensis de Barjac，1978，簡稱BTI）的活性粉劑為菌源，進行以下的試驗：1.BTI對幼蟲的活性，2.水溫對白腹叢蚊幼蟲感染BTI的影響，3.感染時間和三種蚊幼蟲死亡率的關係。4.白腹叢蚊幼蟲腸道及體液pH值在感染後的變化。5.感染後的組織學觀察。所得到的結果如下：（1）埃及斑蚊幼蟲對BTI最敏感，熱帶家蚊次之。而白腹叢蚊最不敏感。其LC_(50)依次分別為0.02742±0.00157 ppm，0.04073±0.00474 ppm及0.13423±0.00575 ppm。（2）在38℃以內，溫度愈高，BTI對白腹叢蚊幼蟲之活性愈大。水溫10℃時，LC_(50)為0.25705±0.1877 ppm，25℃時為0.13423±0.00575 ppm，38℃時則為0.10110±0.00651 ppm。（3）在感染BTI 4小時之後白腹叢蚊幼蟲開始死亡，10小時之後，死亡率為84%，而埃及斑蚊及熱帶家蚊之幼蟲則在感染兩小時後開始死亡，隨著時間增加，死亡率也增加。7小時後，死亡率分別為91%及94%。（4）腸液pH值在處理1小時之後由8.54±0.09增加為9.30±0.19，兩小時之後pH值下降，至6小時之後趨近中性（7.16±0.72）。體液pH值原為7.93±0.14，處理3小時之後下降，10小時之後降為中性偏弱酸（6.37±0.20）。（5）在幼蟲中腸部位發現有細胞腫大，黏液增加，腸道組織結構的破壞。此外並觀察到後腸細胞表皮內膜變薄，中腸細胞在感染後亦漸變薄，腸腔加大，細胞質顆粒減少，在中腸前段發現大量BTI孢子，體壁及消化道的肌肉產生解離現象；隨著時間的增加，腸腔發現大量的BTI營養體，中腸上皮細胞的細胞質內發現大量空泡。15小時後，埃及斑蚊及熱帶家蚊腸腔中發現有革蘭氏陰性菌，24小時後陰性菌大增，陽性菌相對的減少。

並列摘要

Larvae of Armigeres subalbatus, Culex quinquefasciatus, and Aedes aegypti, three mosquitoes common in Taiwan, were exposed to wettable powder of the bacterial insecticide, Bacillus thuringiensis var. israelensis (BTl), at various concentrations at 25°C. Susceptibility to BTI infection is greatest for larvae of Ae. aegypti, less for Cx. quinquefasciatus, and least for Ar. subalbatus, with LC_(50) values of 0.027 ± 0.002ppm, 0.041 ± 0.005 ppm and 0.134 ±0.006 ppm, respectively. At BTI concentration of 0.5 ppm , Ar. subalbatus larvae died 4 hr after infection with mortality increasing to 84% after 10 hr, whereas both Cx quinquefasciatus and Ae. aegypti larvae died 2 hr post-infection with mortality increasing after 7 hr to 94% and 91%, respectively. Beginning 1-3 hr after BTI infection, both cuticular intima of hindgut and epithelium of midgut became progressively thinner, the number of cytoplasmic granules decreased, the lumen of the gut enlarged, large numbers of BTI spores were found at the anterior end of the midgut, and whole muscles were lysed in infected larvae. After 9 hr of infection, many vegetative cells were found in the lumen of the anterior region of midgut, and vesicles increased in the cytoplasm. Gram negative bacteria were found in the larvae of Ae. aegypti and Cx quinquefasciatus at 15 hr post-infection, increasing at 24 hr, while the Gram positive bacteria became relatively decreased 24 hr after infection. This result could explain the reason why the Gram positive BTI cannot recycle in the nature.