First field and laboratory trial of VectorBac® WG around the airport zone of the capital city of Libreville, Gabon

Sevidzem Silas  Lendzele; Poungou  Natacha; Okane  Glen; Brizard Zongo  Sylvie; Rodrigue Mintsa  Nguema

doi:10.59400/ephr2038

Sevidzem Silas Lendzele Laboratoire d’écologie des Maladies Transmissibles (LEMAT), Université Libreville Nord, Libreville 1177, Gabon
Poungou Natacha Laboratoire d’écologie des Maladies Transmissibles (LEMAT), Université Libreville Nord, Libreville 1177, Gabon
Okane Glen École Nationale des Eaux et Forêts (ENEF), Libreville 3960, Gabon
Brizard Zongo Sylvie École Nationale des Eaux et Forêts (ENEF), Libreville 3960, Gabon
Rodrigue Mintsa Nguema Laboratoire d’écologie des Maladies Transmissibles (LEMAT), Université Libreville Nord, Libreville 1177, Gabon

Article ID: 2038

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DOI: https://doi.org/10.59400/ephr2038

Keywords: Aedes; Anopheles; Culex; larva; VectorBac®; Akanda

Abstract

Context/Purpose: The urban ecosystem of Akanda behind the airport of the capital city of Libreville in Gabon, harbors diverse and dense mosquito larval habitats and hotspots for malaria and arboviruses transmission. To effectively conduct vector control, it is imperative to adopt an integrated approach by adding biolarvicides to the toolbox. The main objective of this study is to evaluate the efficacy of a biolarvicide under laboratory and field conditions. Methods: In Gabon, this current pilot and preliminary study sought to test the efficacy of the biolarvicide VectorBac® Water dispersable Granule (WG) (VBG) during the rainy season period (March to May 2024) under field and laboratory conditions following the 2005 World Health Organisation protocol. Results: For the bioassay of VBG, in the laboratory, the required dose to kill 88% and 100% of the larvae in rearing cups was 0.001 g/mL and 0.01 g/mL respectively. Under field conditions, the percentage larval density reduction irrespective of the microhabitat type ranged from 90 to 100% and the mosquito larval density reduction between test and control groups in the field differed statistically (X²=34; p = 0.026). Conclusion: The larvae from Akanda tested under field and laboratory conditions were very sensitive to the standard dose recommended by the manufacturer after 24 hrs post-treatment with VBG. This pilot study provides baseline information that is required to conduct a longitudinal study to evaluate the residual effect of VBG in different ecological settings in Gabon.

References

[1]Lendzele SS, Ulrich MP, Boris M, et al. Distribution and Characterization of Culicids (Diptera: Culicidae) in Two Urban Communes of Estuaire Province of Gabon. Asian Journal of Biological Sciences. 2023; 16(4): 681–691. doi: 10.3923/ajbs.2023.681.691

[2]Sevidzem SL, Pamba R, Koumba AA, et al. Typology of Breeding Sites and Species Diversity of Culicids (Diptera: Culicidae) in Akanda and its Environs (North West, Gabon). European Journal of Biology and Biotechnology. 2020; 1(1). doi: 10.24018/ejbio.2020.1.1.13

[3]Obame-Nkoghe J, Makanga BK, Zongo SB, et al. Urban Green Spaces and Vector-Borne Disease Risk in Africa: The Case of an Unclean Forested Park in Libreville (Gabon, Central Africa). International Journal of Environmental Research and Public Health. 2023; 20(10): 5774. doi: 10.3390/ijerph20105774

[4]Djènontin A, Pennetier C, Zogo B, et al. Field efficacy of Vectobac GR as a mosquito larvicide for the control of anopheline and culicine mosquitoes in natural habitats in Benin, West Africa. PLoS ONE. 2014; 9(2): e87934. doi: 10.1371/journal.pone.0087934

[5]Poungou N, Sevidzem SL, Koumba AA, et al. Mosquito-Borne Arboviruses Occurrence and Distribution in the Last Three Decades in Central Africa: A Systematic Literature Review. Microorganisms. 2023; 12(1): 4. doi: 10.3390/microorganisms12010004

[6]WHO. Guidelines for laboratory and field testing of mosquito larvicides. Available online: https://iris.who.int/handle/10665/69101 (accessed on 13 September 2024).

[7]Sevidzem S.L., Tchawe R, Roland ZK, et al. Insecticide coated screen models reduce insect-vector population in a pasture area in ngaoundere, Cameroon. Trends in Applied Sciences Research. 2019; 14(2): 80–89. doi: 10.3923/tasr.2019.80.89

[8]Diédhiou SM, Konaté L, Doucouré S, et al. Efficacy of three biological larvicides and a growth regulator against Anopheles arabiensis in Senegal (French). Bulletin de la Société de pathologie exotique. 2017; 110(2): 102–115. doi: 10.1007/s13149-016-0531-4

[9]Souleymane MI, Soma DD, Maiga AA, et al. Laboratory study of the larvicidal activity of Bacillus thuringiensis israelensis and Bacillus sphaericus with a view to biological control of Culex pipiens and Anopheles gambiae s.l larvae in Niger (French). International Journal of Advanced Research. 2022; 10(02): 1004–1012. doi: 10.21474/ijar01/14306