Emerging Resistance in Anopheles stephensi Larvae to the Larvicide Temephos in Chennai, India.

IF 1.6 4区医学 Q3 PUBLIC, ENVIRONMENTAL & OCCUPATIONAL HEALTH

American Journal of Tropical Medicine and Hygiene Pub Date : 2025-08-19 DOI:10.4269/ajtmh.25-0232

Sangamithra Ravishankaran, Shalu Thomas, Aswin Asokan, Johnson Amala Justin Nalapatty Anthonysamy, Manu Thomas Mathai, Vaishali Verma, Raghavendra Kamaraju, Alex Eapen

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Abstract

This study aimed to evaluate the susceptibility of immature Anopheles stephensi to temephos formulation, a primary antilarval intervention currently in operational use. The assessment was conducted against both the WHO-recommended discriminatory dosage with temephos (0.25 parts per million [ppm]) and the operational field dosage with temephos 50% emulsifiable concentrate (EC; 1 ppm). F1 generation immature An. stephensi from two areas of Chennai, India was used for the study. The larvae (F1) from both areas were fully susceptible to the WHO discriminatory dosage. Larval susceptibility tests with temephos 50% EC observed 100% mortality in Thiruvanmiyur strains at 40 ppm (lethal concentration at which 99% of the exposed larvae were dead [LC99]: 37.47-45.06 ppm). However, Adyar strains exhibited 98.7% mortality at 50 ppm (LC99: 59.79 ppm). Anopheles stephensi larvae from both areas showed resistance to operational field dosage (1 ppm). Prolonged insecticide exposure precipitates resistance, highlighting the need for routine larvicide efficacy monitoring to support disease elimination efforts.

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钦奈地区斯氏按蚊幼虫对杀幼虫剂双硫磷的新抗性。

本研究旨在评估未成熟的斯氏按蚊对双硫磷制剂的敏感性，双硫磷制剂是目前使用的一种主要的抗幼虫干预措施。评估是根据世卫组织推荐的双硫磷区分剂量（百万分之0.25）和双硫磷50%乳化浓缩物的现场操作剂量（百万分之1）进行的。F1代未成熟安。来自印度金奈两个地区的斯蒂芬氏菌被用于研究。这两个地区的幼虫（F1）对WHO区分剂量完全敏感。用双硫磷50% EC进行幼虫敏感性试验，发现40 ppm（暴露致死浓度：37.47 ~ 45.06 ppm， 99%的幼虫死亡）下，特鲁凡米蚊幼虫死亡率为100%。而Adyar菌株在50 ppm时的死亡率为98.7% （LC99: 59.79 ppm）。两个地区的斯氏按蚊幼虫对现场操作剂量（1ppm）均表现出抗药性。长期接触杀虫剂会产生抗药性，因此需要定期监测杀幼虫剂的药效，以支持消除疾病的努力。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

American Journal of Tropical Medicine and Hygiene 医学-公共卫生、环境卫生与职业卫生

CiteScore

6.20

自引率

3.00%

发文量

508

审稿时长

3 months

期刊介绍： The American Journal of Tropical Medicine and Hygiene, established in 1921, is published monthly by the American Society of Tropical Medicine and Hygiene. It is among the top-ranked tropical medicine journals in the world publishing original scientific articles and the latest science covering new research with an emphasis on population, clinical and laboratory science and the application of technology in the fields of tropical medicine, parasitology, immunology, infectious diseases, epidemiology, basic and molecular biology, virology and international medicine. The Journal publishes unsolicited peer-reviewed manuscripts, review articles, short reports, images in Clinical Tropical Medicine, case studies, reports on the efficacy of new drugs and methods of treatment, prevention and control methodologies,new testing methods and equipment, book reports and Letters to the Editor. Topics range from applied epidemiology in such relevant areas as AIDS to the molecular biology of vaccine development. The Journal is of interest to epidemiologists, parasitologists, virologists, clinicians, entomologists and public health officials who are concerned with health issues of the tropics, developing nations and emerging infectious diseases. Major granting institutions including philanthropic and governmental institutions active in the public health field, and medical and scientific libraries throughout the world purchase the Journal. Two or more supplements to the Journal on topics of special interest are published annually. These supplements represent comprehensive and multidisciplinary discussions of issues of concern to tropical disease specialists and health issues of developing countries