Evaluation of a long-lasting microbial larvicide against Culex quinquefasciatus and Aedes aegypti under laboratory and a semi-field trial

IF 3 2区医学 Q1 PARASITOLOGY

Parasites & Vectors Pub Date : 2024-09-14 DOI:10.1186/s13071-024-06465-5

Hyago Luiz Rique, Heverly Suzany Gouveia Menezes, Maria Alice Varjal Melo-Santos, Maria Helena Neves Lobo Silva-Filha

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引用次数: 0

Abstract

Microbial larvicides containing both LysiniBacillus sphaericus and Bacillus thuringiensis svar. israelensis (Bti) insecticidal crystals can display advantages for mosquito control. This includes a broader action against larvae that are refractory to the Binary (Bin) toxin from L. sphaericus, as Bin-resistant Culex quinquefasciatus and Aedes aegypti naturally refractory larvae, which often co-habit urban areas of endemic countries for arboviruses. Our principal goal was to assess the toxicity of a combined L. sphaericus/Bti larvicide (Vectomax FG™) to Cx. quinquefasciatus (susceptible CqS and Bin-resistant CqR) and Ae. aegypti (Rocke) and to determine its persistence in the breeding sites with those larvae. The toxicity of a combined L. sphaericus/Bti product (VectoMax FG™) to larvae was performed using bioassays, and persistence was evaluated in simulate field trials carried out under the shade, testing two label concentrations during 12 weeks. A laboratory strain SREC, established with CqS and CqR larvae, was kept during four generations to evaluate the ability of the L. sphaericus/Bti to eliminate resistant larvae. The L. sphaericus/Bti showed toxicity (mg/L) to larvae from all strains with a decreasing pattern for CqS (LC50 = 0.006, LC90 = 0.030), CqR (LC50 = 0.009, LC90 = 0.069), and Rocke (LC50 = 0.042, LC90 = 0.086). In a simulated field trial, the larvicide showed a persistence of 6 weeks and 8 weeks, controlling larvae from all strains in containers with 100 L of water, using 2 g or 4 g per container (100 L), respectively. The treatment of SREC larvae with L. sphaericus/Bti showed its capacity to eliminate the Bin-resistant individuals using suitable concentrations to target those larvae. Our results showed the high efficacy and persistence of the L. sphaericus/Bti larvicide to control Cx. quinquefasciatus and Ae. aegypti that might cohabit breeding sites. These findings demonstrated that such larvicides can be an effective tool for controlling those species in urban areas with a low potential for selecting resistance.

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在实验室和半田间试验中评估针对库蚊和埃及伊蚊的长效微生物杀幼虫剂

同时含有 LysiniBacillus sphaericus 和 Bacillus thuringiensis svar. israelensis（Bti）杀虫晶体的微生物杀幼虫剂在控制蚊虫方面具有优势。这包括更广泛地作用于对唾液腺芽孢杆菌二元毒素（Bin）耐药的幼虫，如对Bin耐药的库蚊和埃及伊蚊天然耐药幼虫，它们经常共同生活在虫媒病毒流行国家的城市地区。我们的主要目标是评估 L. sphaericus/Bti 组合杀幼虫剂（Vectomax FG™）对五步蛇（易感 CqS 和 Bin 抗性 CqR）和埃及伊蚊（Rocke）的毒性，并确定其在这些幼虫繁殖地的持久性。使用生物测定法对 L. sphaericus/Bti 组合产品（VectoMax FG™）对幼虫的毒性进行了测定，并在 12 周内对两种标签浓度的产品进行了测试，在阴凉处进行的模拟现场试验中对其持久性进行了评估。用 CqS 和 CqR 幼虫建立的实验室菌株 SREC 经过四代饲养，以评估 L. sphaericus/Bti 清除抗性幼虫的能力。L. sphaericus/Bti 对所有菌株的幼虫都有毒性（毫克/升），对 CqS（LC50 = 0.006，LC90 = 0.030）、CqR（LC50 = 0.009，LC90 = 0.069）和 Rocke（LC50 = 0.042，LC90 = 0.086）的毒性呈下降趋势。在模拟田间试验中，杀幼虫剂的持效期分别为 6 周和 8 周，在装有 100 升水的容器中，每个容器（100 升）分别使用 2 克或 4 克，可控制所有菌株的幼虫。用 L. sphaericus/Bti 处理 SREC 幼虫的结果表明，用适当的浓度来消灭对 Bin 产生抗药性的幼虫个体是可行的。我们的研究结果表明，L. sphaericus/Bti杀幼虫剂对控制可能共居繁殖地的五步蛇和埃及伊蚊具有很高的效力和持久性。这些研究结果表明，这种杀幼虫剂可以成为控制城市地区这些物种的有效工具，而且产生抗药性的可能性较低。

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来源期刊

Parasites & Vectors 医学-寄生虫学

CiteScore

6.30

自引率

9.40%

发文量

433

审稿时长

1.4 months

期刊介绍： Parasites & Vectors is an open access, peer-reviewed online journal dealing with the biology of parasites, parasitic diseases, intermediate hosts, vectors and vector-borne pathogens. Manuscripts published in this journal will be available to all worldwide, with no barriers to access, immediately following acceptance. However, authors retain the copyright of their material and may use it, or distribute it, as they wish. Manuscripts on all aspects of the basic and applied biology of parasites, intermediate hosts, vectors and vector-borne pathogens will be considered. In addition to the traditional and well-established areas of science in these fields, we also aim to provide a vehicle for publication of the rapidly developing resources and technology in parasite, intermediate host and vector genomics and their impacts on biological research. We are able to publish large datasets and extensive results, frequently associated with genomic and post-genomic technologies, which are not readily accommodated in traditional journals. Manuscripts addressing broader issues, for example economics, social sciences and global climate change in relation to parasites, vectors and disease control, are also welcomed.