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Background <p>Understanding mosquito larval ecology is crucial for effective vector control strategies. While much is known about <i>Anopheles</i> larval habitat distribution, the impact of landscape (urban vs. rural) on <i>Anopheles stephensi</i> larval distribution and population dynamics in Ethiopia remains unclear.</p> Methods <p>A longitudinal study was conducted from February 2023 to December 2024 in aquatic habitats in urban, peri-urban, and rural areas of Dire Dawa City Administration, eastern Ethiopia. Mosquito larvae and pupae were collected and reared in a field insectary until adult emergence. The female <i>Anopheles</i> were morphologically identified and further confirmed via polymerase chain reaction (PCR). The physicochemical parameters of the larval habitats were measured via a HANNA multiparameter water probe. Statistical analyses included general linear models, ANOVA, logistic regression, paired sample t tests, chi-square tests, principal component analysis and correlation analyses to assess larval presence, density, and distribution in relation to water physicochemical parameters across the three ecological settings.</p> Results <p>A total of 23,526 larvae and 1808 pupae of <i>Anopheles</i> mosquitoes were collected from 856 man-made habitats (bricks, plastic sheets, steel drums, tire tracks, canal ditches, and barrels) and 53 natural habitats (river edges, animal hoof prints, ponds, and swamps) in urban, peri-urban, and rural areas. Uncovered cemented cisterns were the main human-made larval habitats; river edges were the main natural habitats. <i>Anopheles</i> larvae were absent in the steel drums and plastic barrels at the rural sites. <i>Anopheles</i> larval density significantly differed across the different ecological settings (F = 7.8, df = 1, 908, p = 0.005) and among the different larval habitat types (F = 326.2, df = 1, 907, p &lt; 0.001). Among the 2934 reared adults, 74.8% (2194/2934) were <i>An. stephensi</i>, 21.7% (636/2934) were <i>An. arabiensis</i>, and 3.0% were other species (<i>An. pharoensis</i>, <i>An. coustani</i>, <i>An. amharicus</i>, <i>An. pretoriensis</i>). <i>An. stephensi</i> shares habitats with <i>An. arabiensis</i> and <i>An. amharicus</i>. Larval presence was significantly associated with brick factory proximity (χ2 = 23.8, df = 5, p &lt; 0.001), land use/surrounding environment (χ2 = 32.6, df = 13, p = 0.002), vegetation (χ2 = 27.1, df = 12, p = 0.008), shade coverage (χ2 = 25.9, df = 15, p = 0.039), substrate type (χ2 = 34.1, df = 6, p &lt; 0.001), and competitor/predator presence (χ2 = 14.6, df = 1, p = 0.001). However, larval presence was not associated with the presence of larval interventions (χ2 = 1.3, df = 1, p = 0.250). Water pH (r = 0.26, n = 102, p &lt; 0.050) and water pressure (r = 0.21, n = 102, p &lt; 0.050) were the only water physicochemical parameters that were positively correlated with <i>An. stephensi</i> presence.</p> Conclusion <p><i>Anopheles stephensi</i> was dominant in urban areas but was also present in rural areas. Existing larval source management methods do not prevent <i>Anophel</i>es from occurring in many habitats, indicating an urgent need for improved strategies.</p>

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Anopheles larval ecology and physicochemical characterization of larval habitats in Dire Dawa: an area colonized by Anopheles stephensi in Eastern Ethiopia

  • 期刊论文

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  • 发表日期：

    2026年8月1日

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  • Ephrem Abiy,
  • Teshome Degefa,
  • Meshesha Balkew,
  • Hailu Merga,
  • Deneke Zewdu,
  • Alamayo Ayala,
  • Harrysone Atieli,
  • Ming-Chieh Lee,
  • Guofa Zhou,
  • Guiyun Yan,
  • Delenasaw Yewhalaw

摘要

Background

Understanding mosquito larval ecology is crucial for effective vector control strategies. While much is known about Anopheles larval habitat distribution, the impact of landscape (urban vs. rural) on Anopheles stephensi larval distribution and population dynamics in Ethiopia remains unclear.

Methods

A longitudinal study was conducted from February 2023 to December 2024 in aquatic habitats in urban, peri-urban, and rural areas of Dire Dawa City Administration, eastern Ethiopia. Mosquito larvae and pupae were collected and reared in a field insectary until adult emergence. The female Anopheles were morphologically identified and further confirmed via polymerase chain reaction (PCR). The physicochemical parameters of the larval habitats were measured via a HANNA multiparameter water probe. Statistical analyses included general linear models, ANOVA, logistic regression, paired sample t tests, chi-square tests, principal component analysis and correlation analyses to assess larval presence, density, and distribution in relation to water physicochemical parameters across the three ecological settings.

Results

A total of 23,526 larvae and 1808 pupae of Anopheles mosquitoes were collected from 856 man-made habitats (bricks, plastic sheets, steel drums, tire tracks, canal ditches, and barrels) and 53 natural habitats (river edges, animal hoof prints, ponds, and swamps) in urban, peri-urban, and rural areas. Uncovered cemented cisterns were the main human-made larval habitats; river edges were the main natural habitats. Anopheles larvae were absent in the steel drums and plastic barrels at the rural sites. Anopheles larval density significantly differed across the different ecological settings (F = 7.8, df = 1, 908, p = 0.005) and among the different larval habitat types (F = 326.2, df = 1, 907, p < 0.001). Among the 2934 reared adults, 74.8% (2194/2934) were An. stephensi, 21.7% (636/2934) were An. arabiensis, and 3.0% were other species (An. pharoensis, An. coustani, An. amharicus, An. pretoriensis). An. stephensi shares habitats with An. arabiensis and An. amharicus. Larval presence was significantly associated with brick factory proximity (χ2 = 23.8, df = 5, p < 0.001), land use/surrounding environment (χ2 = 32.6, df = 13, p = 0.002), vegetation (χ2 = 27.1, df = 12, p = 0.008), shade coverage (χ2 = 25.9, df = 15, p = 0.039), substrate type (χ2 = 34.1, df = 6, p < 0.001), and competitor/predator presence (χ2 = 14.6, df = 1, p = 0.001). However, larval presence was not associated with the presence of larval interventions (χ2 = 1.3, df = 1, p = 0.250). Water pH (r = 0.26, n = 102, p < 0.050) and water pressure (r = 0.21, n = 102, p < 0.050) were the only water physicochemical parameters that were positively correlated with An. stephensi presence.

Conclusion

Anopheles stephensi was dominant in urban areas but was also present in rural areas. Existing larval source management methods do not prevent Anopheles from occurring in many habitats, indicating an urgent need for improved strategies.