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Purpose <p>The global resurgence of the common bed bug, <i>Cimex lectularius</i> L. (Hemiptera: Cimicidae), is driven by widespread insecticide resistance. In sub-Saharan Africa, intensive use of pyrethroids for malaria vector control may exert collateral selection pressure on bed bug populations. This study aimed to assess the phenotypic susceptibility of Nigerian <i>C. lectularius</i> populations to four major classes of public health insecticides and to evaluate community knowledge and practices regarding bed bug infestations.</p> Methods <p>A cross-sectional survey was conducted in five Local Government Areas of Kwara Central District, Nigeria, using a semi-structured questionnaire. Bed bugs collected from infested dwellings were exposed to WHO insecticide-impregnated papers at diagnostic concentrations for malaria vectors: deltamethrin (0.05%), pirimiphos-methyl (0.25%), DDT (4%), and propoxur (0.1%). Knockdown was recorded over 60&#xa0;min, and mortality after 24&#xa0;h. Repellency was assessed using a two-choice test for two populations.</p> Results <p>Survey data revealed low public awareness, with 38.4% of respondents unaware of infestation causes. All five field populations exhibited resistance to all four insecticide classes, with 24-h mortality rates (0–70%) well below the WHO 90% susceptibility threshold. Pirimiphos-methyl was the most toxic insecticide, achieving the highest mortality (50–70%) in four populations. Kaplan–Meier analysis confirmed severely delayed knockdown, with median knockdown times (KDT₅₀) exceeding 60&#xa0;min for most insecticide–population combinations. Propoxur showed the strongest repellent effect (up to 73.3%).</p> Conclusion <p>This study provides the first evidence of widespread phenotypic resistance to multiple public health insecticide classes in Nigerian <i>C. lectularius</i> populations. The high-level resistance to pyrethroids and DDT raises concerns about the potential collateral impacts of sustained insecticide pressure from malaria vector control on urban pest populations. These findings underscore the urgent need for integrated pest management and routine resistance monitoring in malaria-endemic regions.</p>

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Phenotypic Resistance to Public Health Insecticides in Field Populations of the Bed Bug, Cimex lectularius L. (Hemiptera: Cimicidae), from Kwara State, Nigeria

  • 期刊论文

  • 发表日期：

    2026年7月27日

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  • Olukayode James Adelaja,
  • Rhoda Ibukunoluwa Yusuf,
  • Ayobami Dorcas Olaleye,
  • Faith Zaphaniah,
  • Adeolu Taiwo Ande

摘要

Purpose

The global resurgence of the common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), is driven by widespread insecticide resistance. In sub-Saharan Africa, intensive use of pyrethroids for malaria vector control may exert collateral selection pressure on bed bug populations. This study aimed to assess the phenotypic susceptibility of Nigerian C. lectularius populations to four major classes of public health insecticides and to evaluate community knowledge and practices regarding bed bug infestations.

Methods

A cross-sectional survey was conducted in five Local Government Areas of Kwara Central District, Nigeria, using a semi-structured questionnaire. Bed bugs collected from infested dwellings were exposed to WHO insecticide-impregnated papers at diagnostic concentrations for malaria vectors: deltamethrin (0.05%), pirimiphos-methyl (0.25%), DDT (4%), and propoxur (0.1%). Knockdown was recorded over 60 min, and mortality after 24 h. Repellency was assessed using a two-choice test for two populations.

Results

Survey data revealed low public awareness, with 38.4% of respondents unaware of infestation causes. All five field populations exhibited resistance to all four insecticide classes, with 24-h mortality rates (0–70%) well below the WHO 90% susceptibility threshold. Pirimiphos-methyl was the most toxic insecticide, achieving the highest mortality (50–70%) in four populations. Kaplan–Meier analysis confirmed severely delayed knockdown, with median knockdown times (KDT₅₀) exceeding 60 min for most insecticide–population combinations. Propoxur showed the strongest repellent effect (up to 73.3%).

Conclusion

This study provides the first evidence of widespread phenotypic resistance to multiple public health insecticide classes in Nigerian C. lectularius populations. The high-level resistance to pyrethroids and DDT raises concerns about the potential collateral impacts of sustained insecticide pressure from malaria vector control on urban pest populations. These findings underscore the urgent need for integrated pest management and routine resistance monitoring in malaria-endemic regions.