Resistance of Anopheles stephensi to selected insecticides used for indoor residual spraying and long-lasting insecticidal nets in Ethiopia

• Published in: Malaria Journal
• Main Authors: Abebe Teshome, Berhanu Erko, Lemu Golassa, Gedeon Yohannes, Seth R. Irish, Sarah Zohdy, Melissa Yoshimizu, Sisay Dugassa
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2023
• Subjects: Anopheles stephensi; Long-lasting insecticidal nets; Indoor residual spraying; Susceptibility; Malaria; Vector control; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic; Haro; Lemma
• Online Access: https://doi.org/10.1186/s12936-023-04649-5; https://doaj.org/article/93b48c2b1a9a4d19937a4cdf15bb48f2

Abstract Background Malaria, transmitted by the bite of infective female Anopheles mosquitoes, remains a global public health problem. The presence of invasive Anopheles stephensi, capable of transmitting Plasmodium vivax and Plasmodium falciparum, was first reported in Ethiopia in 2016. The ecology of this mosquito species differs from that of Anopheles arabiensis, the primary malaria vector in Ethiopia. This study aimed to evaluate the efficacy of selected insecticides, which are used in indoor residual spraying (IRS) and selected long-lasting insecticidal nets (LLINs) for malaria vector control against adult An. stephensi. Methods Anopheles stephensi mosquitoes were collected as larvae and pupae from Awash Subah Kilo Town and Haro Adi village, Ethiopia. Adult female An. stephensi, reared from larvae and pupae collected from the field, aged 3–5 days were exposed to impregnated papers of IRS insecticides (propoxur 0.1%, bendiocarb 0.1%, pirimiphos-methyl 0.25%), and insecticides used in LLINs (alpha-cypermethrin 0.05%, deltamethrin 0.05% and permethrin 0.75%), using diagnostic doses and WHO test tubes in a bio-secure insectary at Aklilu Lemma Institute of Pathobiology, Addis Ababa University. For each test and control tube, batches of 25 female An. stephensi were used to test each insecticide used in IRS. Additionally, cone bioassay tests were conducted to expose An. stephensi from the reared population to four brands of LLINs, MAGNet™ (alpha-cypermethrin), PermaNet® 2.0 (deltamethrin), DuraNet© (alpha-cypermethrin) and SafeNet® (alpha-cypermethrin). A batch of ten sugar-fed female mosquitoes aged 2–5 days was exposed to samples taken from five positions/sides of a net. The data from all replicates were pooled and descriptive statistics were used to describe features of the data. Results All An. stephensi collected from Awash Subah Kilo Town and Haro Adi village (around Metehara) were resistant to all tested insecticides used in both IRS and LLINs. Of the tested LLINs, only MAGNet™ (alpha-cypermethrin active ...