Insecticidal potency of bacterial species Bacillus thuringiensis SV2 and Serratia nematodiphila SV6 against larvae of mosquito species Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus
Insecticidal potency of bacterial species Bacillus thuringiensis SV2 and Serratia nematodiphila SV6 against larvae of mosquito species Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus
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苏云金芽孢杆菌 SV2 和线虫沙雷氏菌 SV6 对埃及伊蚊、斯氏按蚊和致倦库蚊幼虫的杀虫效力
作者：
C. Patil;S. Patil;B. Salunke;R. B. Salunkhe
世界范围内分离具有改进功效的新型杀蚊幼虫细菌的巨大努力为控制具有公共卫生重要性的病媒传播疾病提供了重大希望。在本研究中，两个本地细菌分离物，苏云金芽孢杆菌（Bt SV 2）和沙雷氏菌属物种（SV 6）对埃及伊蚊，斯氏按蚊和致倦库蚊的早期四龄幼虫的杀蚊幼虫潜力进行了评价，参照B。苏云金Israelensis（Bti）H 14.天然革兰氏阳性，孢子形成Bt SV 2分离株显示出100%的死亡率对埃及伊蚊，斯氏按蚊，致倦库蚊，在平行的Bti H14菌株的早期四龄。24 h后，Bt SV 2对埃及伊蚊、斯氏按蚊和致倦库蚊的致死率分别为98%、89%和80.67%，Bti H14对埃及伊蚊、斯氏按蚊和致倦库蚊的致死率分别为92%、98.33%和60%。暴露48 h后，Serratia SV 6对致倦库蚊（100%）的活性最高，其次是斯氏按蚊（95%）和埃及伊蚊（91%）。与Bti H14和Bt SV 2相比，革兰氏阴性沙雷氏菌SV 6对埃及伊蚊、斯氏按蚊和致倦库蚊的早期四龄表现出延迟毒性。暴露12小时后，所有治疗的相对死亡率显示出不同的毒性，暴露时间，细菌治疗，和蚊子物种。基于16 S rRNA基因序列比对的系统发育重建证实了菌株的遗传相关性，这表明菌株SV 2与B有很强的聚类。苏云金杆菌和SV 6菌株与嗜二色沙雷氏菌的分离。总之，天然分离物B.与BtiH 14相比，苏云金杆菌SV 2显示出显著的毒性，而沙雷氏菌SV 6对几种蚊子物种显示出较低和延迟的毒性。这些化合物可作为新型细菌杀虫剂用于蚊媒疾病的防治。据我们所知，这是第一份关于沙雷氏菌属杀蚊幼虫潜力的报告。
The tremendous worldwide efforts to isolate novel mosquito larvicidal bacteria with improved efficacy present significant promise to control vector-borne diseases of public health importance. In the present study, two native bacterial isolates, Bacillus thuringiensis (Bt SV2) and Serratia species (SV6) were evaluated for mosquito larvicidal potential against the early fourth instar larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus with reference to B. thuringiensis subsp. israelensis (Bti) H 14. The native Gram-positive, spore-forming Bt SV2 isolate showed 100% mortality against early fourth instars of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, in parallel to Bti H14 strain. After 24 h, Bt SV2 showed 98%, 89%, and 80.67%, and Bti H14 showed 92%, 98.33%, and 60% mortality against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, respectively. Serratia SV6 showed highest activity against Culex quinquefasciatus (100%) followed by Anopheles stephensi (95%) and Aedes aegypti (91%) after 48 h of exposure. The Gram-negative Serratia SV6 showed delayed toxicity compared to Bti H14 and Bt SV2 against early fourth instars of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. The relative mortality of all treatments after 12-h exposures showed the varied toxicity with respect to exposure time, bacterial treatment, and mosquito species. Genetic relatedness of the strains was confirmed on the basis of phylogenetic reconstructions based on alignment of 16S rRNA gene sequences which indicated a strong clustering of the strain SV2 with B. thuringiensis and the strain SV6 with Serratia nematodiphila. In conclusion, the native isolate B. thuringiensis SV2 showed significant toxicity while Serratia SV6 showed less and delayed toxicity against several mosquito species compared with BtiH14. They may be used as novel bacterial insecticidal agents in mosquito vector-borne disease control. To our knowledge, this is the first report on mosquito larvicidal potential of Serratia species.