泰国受污染水体中滋生的致倦库蚊野外种群对球形芽孢杆菌2362高水平抗性的记录。

Documentation of high-level bacillus Sphaericus 2362 resistance in field populations of Culex quinquefasciatus breeding in polluted water in Thailand.

作者信息

Su Tianyun, Mulla Mir S

机构信息

Department of Entomology, University of California, Riverside, CA 92521, USA.

出版信息

J Am Mosq Control Assoc. 2004 Dec;20(4):405-11.

PMID:15669382

Abstract

Bacillus sphaericus (Bsph) Neide has been recognized as an effective mosquito larvicide since its discovery 20 years ago. Various strains of this agent, such as 2362, 2297, 1593, and C3-41, have been developed, formulated, and field-evaluated against mosquito larvae in different countries. Their high efficacy in controlling mosquitoes breeding in various habitats, especially those in polluted water, has been documented. However, resistance to Bsph has been reported in Culex pipiens complex in both laboratory colonies and natural populations. During our field trials on Bsph water-dispersible granules (WDG) against natural populations of Cx. quinquefasciatus Say in a low-income community, Nonthaburi Province, Thailand, control failure occurred within 4 months after 5 treatments using VectoLex WDG at the dosages of 50-200 mg/m2. The suspected Bsph-resistant Cx. quinquefasciatus mosquitoes were collected and colonized in the laboratory, from which the late stage larvae of generations F14 through F17 were used in bioassays to elucidate the resistance profile. A high level of Bsph resistance was documented in this colony as compared with the susceptible mosquitoes from the same area in Thailand or from California, USA. The resistance ratios (RR) at LC50, depending on reference colonies, were 21,100-28,100-fold against Bsph WDG or greater than 125,000-200,000-fold against Bsph technical-grade material. These Bsph-resistant mosquitoes, however, were completely susceptible to Bacillus thuringiensis var. israelensis, (Bti) preparations, LC50 ranging from 0.017 ppm for technical material with 7000 ITU/mg to 0.052 ppm for water-dispersible granules with 3000 ITU/mg. The RR to mixtures of Bsph + Bti in this highly Bsph-resistant mosquitoes increased steadily upon the increase of Bsph ratios in the mixtures from 50, 75, 90, 95 to 99%. The resistance levels to the mixtures with various ratios of Bsph and Bti, however, were substantially lower than that in Bsph alone, suggesting addition of Bti to Bsph substantially enhanced the mosquitocidal activity (synergism) against these highly Bsph-resistant Cx. quinquefasciatus. Moderate tolerance to low levels of resistance to Bsph/Bti recombinant (RR 7.29-12.75 at LC50 and 5.15-13.40 at LC90) was also noted in this Bsph-resistant population.

摘要

球形芽孢杆菌（Bsph）自20年前被发现以来，就被公认为一种有效的杀蚊幼虫剂。该制剂的各种菌株，如2362、2297、1593和C3 - 41，已在不同国家进行开发、配方研制并针对蚊幼虫进行了田间评估。它们在控制各种生境中，尤其是污染水体中蚊子繁殖方面的高效性已有记录。然而，在实验室种群和自然种群的致倦库蚊复合体中均已报道对球形芽孢杆菌产生了抗性。在泰国暖武里府一个低收入社区，我们使用VectoLex水分散粒剂（WDG）以50 - 200 mg/m²的剂量对致倦库蚊自然种群进行田间试验时，在5次处理后的4个月内出现了防治失败的情况。收集了疑似对球形芽孢杆菌具有抗性的致倦库蚊并在实验室进行饲养繁殖，从第14代到第17代的晚期幼虫用于生物测定以阐明抗性特征。与来自泰国同一地区或美国加利福尼亚州的敏感蚊子相比，该种群对球形芽孢杆菌表现出高水平的抗性。根据参照种群，LC50时的抗性比率（RR），相对于球形芽孢杆菌WDG为21,100 - 28,100倍，相对于球形芽孢杆菌技术级材料大于125,000 - 200,000倍。然而，这些对球形芽孢杆菌具有抗性的蚊子对苏云金芽孢杆菌以色列变种（Bti）制剂完全敏感，LC50范围从技术级材料（7000 ITU/mg）的0.017 ppm到水分散粒剂（3000 ITU/mg）的0.052 ppm。在这种对球形芽孢杆菌高度抗性的蚊子中，随着混合物中球形芽孢杆菌比例从50%、75%、90%、95%增加到99%，对球形芽孢杆菌 + Bti混合物的抗性比率稳步上升。然而，对不同比例球形芽孢杆菌和Bti混合物的抗性水平显著低于单独使用球形芽孢杆菌时，这表明在球形芽孢杆菌中添加Bti可显著增强对这些对球形芽孢杆菌高度抗性的致倦库蚊的杀蚊活性（协同作用）。在这个对球形芽孢杆菌具有抗性的种群中，还观察到对球形芽孢杆菌/ Bti重组体具有中度耐受性（LC50时RR为7.29 - 12.75，LC90时RR为5.15 - 13.40）。