1
|
Thiomela RF, Tchouakui M, Menze BD, Nchoutpouen E, Ngongang-Yipmo ES, Wood O, Horstmann S, Mahob RJ, Fomena A, Wondji CS. Indoor residual spraying of experimental huts in Cameroon highlights the potential of Fludora® Fusion to control wild pyrethroid-resistant malaria vectors. BMC Infect Dis 2024; 24:733. [PMID: 39054424 PMCID: PMC11271210 DOI: 10.1186/s12879-024-09630-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 07/17/2024] [Indexed: 07/27/2024] Open
Abstract
Elevated resistance to pyrethroids in major malaria vectors has led to the introduction of novel insecticides including neonicotinoids. There is a fear that efficacy of these new insecticides could be impacted by cross-resistance mechanisms from metabolic resistance to pyrethroids. In this study, after evaluating the resistance to deltamethrin, clothianidin and mixture of clothianidin + deltamethrin in the lab using CDC bottle assays, the efficacy of the new IRS formulation Fludora® Fusion was tested in comparison to clothianidin and deltamethrin applied alone using experimental hut trials against wild free-flying pyrethroid-resistant Anopheles funestus from Elende and field An. gambiae collected from Nkolondom reared in the lab and released in the huts. Additionally, cone tests on the treated walls were performed each month for a period of twelve months to evaluate the residual efficacy of the sprayed products. Furthermore, the L1014F-kdr target-site mutation and the L119F-GSTe2 mediated metabolic resistance to pyrethroids were genotyped on a subset of mosquitoes from the EHT to assess the potential cross-resistance. All Anopheles species tested were fully susceptible to clothianidin and clothianidin + deltamethrin mixture in CDC bottle assay while resistance was noted to deltamethrin. Accordingly, Fludora® Fusion (62.83% vs 42.42%) and clothianidin (64.42% vs 42.42%) induced significantly higher mortality rates in EHT than deltamethrin (42.42%) against free flying An. funestus from Elende in month 1 (M1) and no significant difference in mortality was observed between the first (M1) and sixth (M6) months of the evaluation (P > 0.05). However, lower mortality rates were recorded against An. gambiae s.s from Nkolondom (mortality rates 50%, 45.56% and 26.68%). In-situ cone test on the wall showed a high residual efficacy of Fludora® Fusion and clothianidin on the susceptible strain KISUMU (> 12 months) and moderately on the highly pyrethroid-resistant An. gambiae strain from Nkolondom (6 months). Interestingly, no association was observed between the L119F-GSTe2 mutation and the ability of mosquitoes to survive exposure to Fludora® Fusion, whereas a trend was observed with the L1014F-kdr mutation. This study highlights that Fludora® Fusion, through its clothianidin component, has good potential of controlling pyrethroid-resistant mosquitoes with prolonged residual efficacy. This could be therefore an appropriate tool for vector control in several malaria endemic regions.
Collapse
Affiliation(s)
- Riccado F Thiomela
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon.
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon.
| | - Magellan Tchouakui
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
| | - Benjamin D Menze
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
| | - Elysee Nchoutpouen
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
| | - Emilie S Ngongang-Yipmo
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Oliver Wood
- 2022 Environmental Science ZA (Pty) Ltd. (Trading As ENVU), 27 Wrench Road, Kempton Park, 1601, ZA, South Africa
| | | | - Raymond J Mahob
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Abraham Fomena
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Charles S Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA, UK.
- International Institute of Tropical Agriculture (IITA), P.O. Box 2008, Yaoundé, Cameroon.
| |
Collapse
|
2
|
Ibrahim SS, Kouamo MFM, Muhammad A, Irving H, Riveron JM, Tchouakui M, Wondji CS. Functional Validation of Endogenous Redox Partner Cytochrome P450 Reductase Reveals the Key P450s CYP6P9a/- b as Broad Substrate Metabolizers Conferring Cross-Resistance to Different Insecticide Classes in Anopheles funestus. Int J Mol Sci 2024; 25:8092. [PMID: 39125661 PMCID: PMC11311542 DOI: 10.3390/ijms25158092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/10/2024] [Accepted: 06/13/2024] [Indexed: 08/12/2024] Open
Abstract
The versatility of cytochrome P450 reductase (CPR) in transferring electrons to P450s from other closely related species has been extensively exploited, e.g., by using An. gambiae CPR (AgCPR), as a homologous surrogate, to validate the role of An. funestus P450s in insecticide resistance. However, genomic variation between the AgCPR and An. funestus CPR (AfCPR) suggests that the full metabolism spectrum of An. funestus P450s might be missed when using AgCPR. To test this hypothesis, we expressed AgCPR and AfCPR side-by-side with CYP6P9a and CYP6P9b and functionally validated their role in the detoxification of insecticides from five different classes. Major variations were observed within the FAD- and NADP-binding domains of AgCPR and AfCPR, e.g., the coordinates of the second FAD stacking residue AfCPR-Y456 differ from that of AgCPR-His456. While no significant differences were observed in the cytochrome c reductase activities, when co-expressed with their endogenous AfCPR, the P450s significantly metabolized higher amounts of permethrin and deltamethrin, with CYP6P9b-AfCPR membrane metabolizing α-cypermethrin as well. Only the CYP6P9a-AfCPR membrane significantly metabolized DDT (producing dicofol), bendiocarb, clothianidin, and chlorfenapyr (bioactivation into tralopyril). This demonstrates the broad substrate specificity of An. funestus CYP6P9a/-b, capturing their role in conferring cross-resistance towards unrelated insecticide classes, which can complicate resistance management.
Collapse
Affiliation(s)
- Sulaiman S. Ibrahim
- Department of Biochemistry, Bayero University, Kano PMB 3011, Nigeria
- Center for Research in Infectious Diseases (CRID), Yaoundé P.O. Box 13591, Cameroon; (M.F.M.K.); (J.M.R.); (M.T.)
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool L3 5QA, UK; (A.M.); (H.I.)
| | - Mersimine F. M. Kouamo
- Center for Research in Infectious Diseases (CRID), Yaoundé P.O. Box 13591, Cameroon; (M.F.M.K.); (J.M.R.); (M.T.)
| | - Abdullahi Muhammad
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool L3 5QA, UK; (A.M.); (H.I.)
- Center of Biotechnology Research, Bayero University, Kano PMB 3011, Nigeria
| | - Helen Irving
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool L3 5QA, UK; (A.M.); (H.I.)
| | - Jacob M. Riveron
- Center for Research in Infectious Diseases (CRID), Yaoundé P.O. Box 13591, Cameroon; (M.F.M.K.); (J.M.R.); (M.T.)
| | - Magellan Tchouakui
- Center for Research in Infectious Diseases (CRID), Yaoundé P.O. Box 13591, Cameroon; (M.F.M.K.); (J.M.R.); (M.T.)
| | - Charles S. Wondji
- Center for Research in Infectious Diseases (CRID), Yaoundé P.O. Box 13591, Cameroon; (M.F.M.K.); (J.M.R.); (M.T.)
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool L3 5QA, UK; (A.M.); (H.I.)
| |
Collapse
|
3
|
Hancock PA, Ochomo E, Messenger LA. Genetic surveillance of insecticide resistance in African Anopheles populations to inform malaria vector control. Trends Parasitol 2024; 40:604-618. [PMID: 38760258 DOI: 10.1016/j.pt.2024.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/19/2024]
Abstract
Insecticide resistance in malaria vector populations poses a major threat to malaria control, which relies largely on insecticidal interventions. Contemporary vector-control strategies focus on combatting resistance using multiple insecticides with differing modes of action within the mosquito. However, diverse genetic resistance mechanisms are present in vector populations, and continue to evolve. Knowledge of the spatial distribution of these genetic mechanisms, and how they impact the efficacy of different insecticidal products, is critical to inform intervention deployment decisions. We developed a catalogue of genetic-resistance mechanisms in African malaria vectors that could guide molecular surveillance. We highlight situations where intervention deployment has led to resistance evolution and spread, and identify challenges in understanding and mitigating the epidemiological impacts of resistance.
Collapse
Affiliation(s)
- Penelope A Hancock
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya; Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Louisa A Messenger
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, USA; Parasitology and Vector Biology (PARAVEC) Laboratory, School of Public Health, University of Nevada, Las Vegas, USA
| |
Collapse
|
4
|
Kamya MR, Nankabirwa JI, Arinaitwe E, Rek J, Zedi M, Maiteki-Sebuguzi C, Opigo J, Staedke SG, Oruni A, Donnelly MJ, Greenhouse B, Briggs J, Krezanoski PJ, Bousema T, Rosenthal PJ, Olwoch P, Jagannathan P, Rodriguez-Barraquer I, Dorsey G. Dramatic resurgence of malaria after 7 years of intensive vector control interventions in Eastern Uganda. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.03.15.24304352. [PMID: 38559091 PMCID: PMC10980127 DOI: 10.1101/2024.03.15.24304352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Background Tororo District, Uganda experienced a dramatic decrease in malaria burden from 2015-19 following 5 years of indoor residual spraying (IRS) with carbamate (Bendiocarb) and then organophosphate (Actellic) insecticides. However, a marked resurgence occurred in 2020, which coincided with a change to a clothianidin-based IRS formulations (Fludora Fusion/SumiShield). To quantify the magnitude of the resurgence, investigate causes, and evaluate the impact of a shift back to IRS with Actellic in 2023, we assessed changes in malaria metrics in regions within and near Tororo District. Methods Malaria surveillance data from Nagongera Health Center, Tororo District was included from 2011-2023. In addition, a cohort of 667 residents from 84 houses was followed from August 2020 through September 2023 from an area bordering Tororo and neighboring Busia District, where IRS has never been implemented. Cohort participants underwent passive surveillance for clinical malaria and active surveillance for parasitemia every 28 days. Mosquitoes were collected in cohort households every 2 weeks using CDC light traps. Female Anopheles were speciated and tested for sporozoites and phenotypic insecticide resistance. Temporal comparisons of malaria metrics were stratified by geographic regions. Findings At Nagongera Health Center average monthly malaria cases varied from 419 prior to implementation of IRS; to 56 after 5 years of IRS with Bendiocarb and Actellic; to 1591 after the change in IRS to Fludora Fusion/SumiShield; to 155 after a change back to Actellic. Among cohort participants living away from the border in Tororo, malaria incidence increased over 8-fold (0.36 vs. 2.97 episodes per person year, p<0.0001) and parasite prevalence increased over 4-fold (17% vs. 70%, p<0.0001) from 2021 to 2022 when Fludora Fusion/SumiShield was used. Incidence decreased almost 5-fold (2.97 vs. 0.70, p<0.0001) and prevalence decreased by 39% (70% vs. 43%, p<0.0001) after shifting back to Actellic. There was a similar pattern among those living near the border in Tororo, with increased incidence between 2021 and 2022 (0.93 vs. 2.40, p<0.0001) followed by a decrease after the change to Actellic (2.40 vs. 1.33, p<0.001). Among residents of Busia, malaria incidence did not change significantly over the 3 years of observation. Malaria resurgence in Tororo was temporally correlated with the replacement of An. gambiae s.s. by An. funestus as the primary vector, with a marked decrease in the density of An. funestus following the shift back to IRS with Actellic. In Busia, An. gambiae s.s. remained the primary vector throughout the observation period. Sporozoite rates were approximately 50% higher among An. funestus compared to the other common malaria vectors. Insecticide resistance phenotyping of An. funestus revealed high tolerance to clothianidin, but full susceptibility to Actellic. Conclusions A dramatic resurgence of malaria in Tororo was temporally associated with a change to clothianidin-based IRS formulations and emergence of An. funestus as the predominant vector. Malaria decreased after a shift back to IRS with Actellic. This study highlights the ability of malaria vectors to rapidly circumvent control efforts and the importance of high-quality surveillance systems to assess the impact of malaria control interventions and generate timely, actionable data.
Collapse
Affiliation(s)
- Moses R. Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- School of Medicine, Makerere University Kampala, Uganda
| | - Joaniter I. Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- School of Medicine, Makerere University Kampala, Uganda
| | | | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | - Maato Zedi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Catherine Maiteki-Sebuguzi
- Infectious Diseases Research Collaboration, Kampala, Uganda
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | - Jimmy Opigo
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | - Sarah G. Staedke
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Ambrose Oruni
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Martin J. Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Bryan Greenhouse
- Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Jessica Briggs
- Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Paul J. Krezanoski
- Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Netherlands
| | - Philip J. Rosenthal
- Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Peter Olwoch
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Prasanna Jagannathan
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, USA
| | | | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, California, USA
| |
Collapse
|
5
|
Ashu FA, Fouet C, Ambadiang MM, Penlap-Beng V, Kamdem C. Adult mosquitoes of the sibling species Anopheles gambiae and Anopheles coluzzii exhibit contrasting patterns of susceptibility to four neonicotinoid insecticides along an urban-to-rural gradient in Yaoundé, Cameroon. Malar J 2024; 23:65. [PMID: 38431623 PMCID: PMC10909279 DOI: 10.1186/s12936-024-04876-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 02/10/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND Neonicotinoids are potential alternatives for controlling pyrethroid-resistant mosquitoes, but their efficacy against malaria vector populations of sub-Saharan Africa has yet to be investigated. The aim of the present study was to test the efficacy of four neonicotinoids against adult populations of the sibling species Anopheles gambiae and Anopheles coluzzii sampled along an urban-to-rural gradient. METHODS The lethal toxicity of three active ingredients for adults of two susceptible Anopheles strains was assessed using concentration-response assays, and their discriminating concentrations were calculated. The discriminating concentrations were then used to test the susceptibility of An. gambiae and An. coluzzii mosquitoes collected from urban, suburban and rural areas of Yaoundé, Cameroon, to acetamiprid, imidacloprid, clothianidin and thiamethoxam. RESULTS Lethal concentrations of neonicotinoids were relatively high suggesting that this class of insecticides has low toxicity against Anopheles mosquitoes. Reduced susceptibility to the four neonicotinoids tested was detected in An. gambiae populations collected from rural and suburban areas. By contrast, adults of An. coluzzii that occurred in urbanized settings were susceptible to neonicotinoids except acetamiprid for which 80% mortality was obtained within 72 h of insecticide exposure. The cytochrome inhibitor, piperonyl butoxide (PBO), significantly enhanced the activity of clothianidin and acetamiprid against An. gambiae mosquitoes. CONCLUSIONS These findings corroborate susceptibility profiles observed in larvae and highlight a significant variation in tolerance to neonicotinoids between An. gambiae and An. coluzzii populations from Yaoundé. Further studies are needed to disentangle the role of exposure to agricultural pesticides and of cross-resistance mechanisms in the development of neonicotinoid resistance in some Anopheles species.
Collapse
Affiliation(s)
- Fred A Ashu
- Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé 9, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, P.O. Box 11 812, Yaoundé, Cameroon
| | - Caroline Fouet
- Department of Biological Sciences, The University of Texas at El Paso, 500 W. University Ave., El Paso, TX, 79968, USA
| | - Marilene M Ambadiang
- Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé 9, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, P.O. Box 11 812, Yaoundé, Cameroon
| | - Véronique Penlap-Beng
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, P.O. Box 11 812, Yaoundé, Cameroon
| | - Colince Kamdem
- Department of Biological Sciences, The University of Texas at El Paso, 500 W. University Ave., El Paso, TX, 79968, USA.
| |
Collapse
|
6
|
Ambadiang M, Fouet C, Ashu F, Bouaka C, Penlap-Beng V, Kamdem C. Anopheles gambiae larvae's ability to grow and emerge in water containing lethal concentrations of clothianidin, acetamiprid, or imidacloprid is consistent with cross-resistance to neonicotinoids. Parasit Vectors 2024; 17:98. [PMID: 38429846 PMCID: PMC10905935 DOI: 10.1186/s13071-024-06188-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 02/08/2024] [Indexed: 03/03/2024] Open
Abstract
BACKGROUND For decades, various agrochemicals have been successfully repurposed for mosquito control. However, preexisting resistance caused in larval and adult populations by unintentional pesticide exposure or other cross-resistance mechanisms poses a challenge to the efficacy of this strategy. A better understanding of larval adaptation to the lethal and sublethal effects of residual pesticides in aquatic habitats would provide vital information for assessing the efficacy of repurposed agrochemicals against mosquitoes. METHODS We reared field-collected mosquito larvae in water containing a concentration of agrochemical causing 100% mortality in susceptible mosquitoes after 24 h (lethal concentration). Using this experimental setup, we tested the effect of lethal concentrations of a pyrrole (chlorfenapyr, 0.10 mg/l), a pyrethroid (deltamethrin, 1.5 mg/l), and three neonicotinoids including imidacloprid (0.075 mg/l), acetamiprid (0.15 mg/l), and clothianidin (0.035 mg/l) on mortality rates, growth, and survival in third-instar larvae of the two sibling species Anopheles gambiae and Anopheles coluzzii collected from Yaoundé, Cameroon. RESULTS We found that An. gambiae and An. coluzzii larvae were susceptible to chlorfenapyr and were killed within 24 h by a nominal concentration of 0.10 mg/l. Consistent with strong resistance, deltamethrin induced low mortality in both species. Lethal concentrations of acetamiprid, imidacloprid, and clothianidin strongly inhibited survival, growth, and emergence in An. coluzzii larvae. By contrast, depending on the active ingredient and the population tested, 5-60% of immature stages of An. gambiae were able to grow and emerge in water containing a lethal concentration of neonicotinoids, suggesting cross-resistance to this class of insecticides. CONCLUSIONS These findings corroborate susceptibility profiles observed in adults and suggest that unintentional pesticide exposure or other cross-resistance processes could contribute to the development of resistance to neonicotinoids in some Anopheles populations.
Collapse
Affiliation(s)
- Marilene Ambadiang
- Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Caroline Fouet
- Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX, USA
| | - Fred Ashu
- Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Calmes Bouaka
- Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Véronique Penlap-Beng
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Colince Kamdem
- Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX, USA.
| |
Collapse
|
7
|
Fouet C, Ashu FA, Ambadiang MM, Tchapga W, Wondji CS, Kamdem C. Clothianidin-resistant Anopheles gambiae adult mosquitoes from Yaoundé, Cameroon, display reduced susceptibility to SumiShield® 50WG, a neonicotinoid formulation for indoor residual spraying. BMC Infect Dis 2024; 24:133. [PMID: 38273227 PMCID: PMC10811947 DOI: 10.1186/s12879-024-09030-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/18/2024] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Chronic exposure of mosquito larvae to pesticide residues and cross-resistance mechanisms are major drivers of tolerance to insecticides used for vector control. This presents a concern for the efficacy of clothianidin, an agricultural neonicotinoid prequalified for Indoor Residual Spraying (IRS). METHODS Using standard bioassays, we tested if reduced susceptibility to clothianidin can affect the efficacy of SumiShield® 50WG, one of four new IRS formulations containing clothianidin. We simultaneously monitored susceptibility to clothianidin and to SumiShield 50WG, testing adults of Anopheles gambiae, An. coluzzii and Culex sp sampled from urban, suburban and agricultural areas of Yaoundé, Cameroon. RESULTS We found that in this geographic area, the level of susceptibility to the active ingredient predicted the efficacy of SumiShield 50WG. This formulation was very potent against populations that reached 100% mortality within 72 h of exposure to a discriminating concentration of clothianidin. By contrast, mortality leveled off at 75.4 ± 3.5% within 7 days of exposure to SumiShield 50WG in An. gambiae adults collected from a farm where the spraying of the two neonicotinoids acetamiprid and imidacloprid for crop protection is likely driving resistance to clothianidin. CONCLUSIONS Despite the relatively small geographic extend of the study, the findings suggest that cross-resistance may impact the efficacy of some new IRS formulations and that alternative compounds could be prioritized in areas where neonicotinoid resistance is emerging.
Collapse
Affiliation(s)
- Caroline Fouet
- Department of Biological Sciences, The University of Texas at El Paso, 500 W. University Ave, El Paso, TX, 79968, USA
| | - Fred A Ashu
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Marilene M Ambadiang
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Williams Tchapga
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
| | - Charles S Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK
| | - Colince Kamdem
- Department of Biological Sciences, The University of Texas at El Paso, 500 W. University Ave, El Paso, TX, 79968, USA.
| |
Collapse
|