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2. Genetic markers associated with the widespread insecticide resistance in malaria vector Anopheles funestus populations across Tanzania

Author

Odero, Joel O., Nambunga, Ismail H., Masalu, John P., Mkandawile, Gustav, Bwanary, Hamis, Hape, Emmanuel E., Njalambaha, Rukiyah M., Tungu, Patrick, Ngowo, Halfan S., Kaindoa, Emmanuel W., Mapua, Salum A., Kahamba, Najat F., Nelli, Luca, Wondji, Charles, Koekemoer, Lizette L., Weetman, David, Ferguson, Heather M., Baldini, Francesco, and Okumu, Fredros O.

Published
2024
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5. Discovery of Knock‐Down Resistance in the Major African Malaria Vector Anopheles funestus.

Author

Odero, Joel O., Dennis, Tristan P. W., Polo, Brian, Nwezeobi, Joachim, Boddé, Marilou, Nagi, Sanjay C., Hernandez‐Koutoucheva, Anastasia, Nambunga, Ismail H., Bwanary, Hamis, Mkandawile, Gustav, Govella, Nicodem J., Kaindoa, Emmanuel W., Ferguson, Heather M., Ochomo, Eric, Clarkson, Chris S., Miles, Alistair, Lawniczak, Mara K. N., Weetman, David, Baldini, Francesco, and Okumu, Fredros O.

Abstract

A major insecticide resistance mechanism in insect pests is knock‐down resistance (kdr) caused by mutations in the voltage‐gated sodium channel (Vgsc) gene. Despite being common in most malaria Anopheles vector species, kdr mutations have never been observed in Anopheles funestus, the principal malaria vector in Eastern and Southern Africa, with resistance mainly being conferred by detoxification enzymes. In a parallel study, we monitored 10 populations of An. funestus in Tanzania for insecticide resistance unexpectedly identified resistance to a banned insecticide, DDT, in the Morogoro region. Through whole‐genome sequencing of 333 An. funestus samples from these populations, we found eight novel amino acid substitutions in the Vgsc gene, including the kdr variant, L976F (equivalent to L995F in An. gambiae), in tight linkage disequilibrium with another (P1842S). The mutants were found only at high frequency in one region and were accompanied by weak signatures of a selective sweep, with a significant decline between 2017 and 2023. Notably, kdr L976F was strongly associated with survivorship to exposure to DDT insecticide, while no clear association was noted with a pyrethroid insecticide (deltamethrin). The WHO prequalifies no DDT products for vector control, and the chemical is banned in Tanzania. Widespread DDT contamination and a legacy of extensive countrywide stockpiles may have selected for this mutation. Continued monitoring is necessary to understand the origin of kdr in An. funestus, and the threat posed to insecticide‐based vector control in Africa. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Discovery of knock-down resistance in the major malaria vectorAnopheles funestusreveals the legacy of persistent DDT pollution

Author

Odero, Joel O., primary, Dennis, Tristan P. W., additional, Polo, Brian, additional, Nwezeobi, Joachim, additional, Boddé, Marilou, additional, Nagi, Sanjay C., additional, Hernandez-Koutoucheva, Anastasia, additional, Nambunga, Ismail H., additional, Bwanary, Hamis, additional, Mkandawile, Gustav, additional, Govella, Nicodem J, additional, Kaindoa, Emmanuel W., additional, Ferguson, Heather M., additional, Ochomo, Eric, additional, Clarkson, Chris S., additional, Miles, Alistair, additional, Lawniczak, Mara K. N., additional, Weetman, David, additional, Baldini, Francesco, additional, and Okumu, Fredros O., additional

Published
2024
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7. Entomological Survey of Sibling Species in the Anopheles funestus Group in Tanzania Confirms the Role of Anopheles parensis as a Secondary Malaria Vector

Author

Mapua, Salum A., primary, Samb, Badara, additional, Nambunga, Ismail H., additional, Mkandawile, Gustav, additional, Bwanaly, Hamis, additional, Kaindoa, Emmanuel W., additional, Odero, Joel, additional, Paliga, John, additional, Kahamba, Najat, additional, Hape, Emmanuel, additional, Govella, Nicodem J., additional, Okumu, Fredros O., additional, and Tripet, Frederic, additional

Published
2024
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13. Aquatic habitats of the malaria vector Anopheles funestus in rural south-eastern Tanzania

Author

Nambunga, Ismail H., Ngowo, Halfan S., Mapua, Salum A., Hape, Emmanuel E., Msugupakulya, Betwel J., Msaky, Dickson S., Mhumbira, Nicolaus T., Mchwembo, Karim R., Tamayamali, Gerald Z., Mlembe, Slyakus V., Njalambaha, Rukiyah M., Lwetoijera, Dickson W., Finda, Marceline F., Govella, Nicodem J., Matoke-Muhia, Damaris, Kaindoa, Emmanuel W., and Okumu, Fredros O.

Published
2020
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15. Wild populations of malaria vectors can mate both inside and outside of human buildings

Author

Nambunga, Ismail H., Msugupakulya, Betwel J., Hape, Emmanuel E., Mshani, Issa H., Kahamba, Najat, Mkandawile, Gustav, Mabula, Daniel M., Njalambaha, Rukiyah M., Kaindoa, Emmanuel W., Muyaga, Letus L., Hermy, Marie R.G., Tripet, Frederic, Ferguson, Heather M., Ngowo, Halfan, and Okumu, Fredros O.

Subjects
parasitic diseases
Abstract

Background:\ud Wild populations of Anopheles mosquitoes are generally thought to mate outdoors in swarms, although once colonized, they also mate readily inside laboratory cages. This study investigated whether the malaria vectors Anopheles funestus and Anopheles arabiensis can also naturally mate inside human dwellings.\ud \ud Method:\ud Mosquitoes were sampled from three volunteer-occupied experimental huts in a rural Tanzanian village at 6:00 p.m. each evening, after which the huts were completely sealed and sampling was repeated at 11:00 p.m and 6 a.m. the next morning to compare the proportions of inseminated females. Similarly timed collections were done inside local unsealed village houses. Lastly, wild-caught larvae and pupae were introduced inside or outside experimental huts constructed inside two semi-field screened chambers. The huts were then sealed and fitted with exit traps, allowing mosquito egress but not entry. Mating was assessed in subsequent days by sampling and dissecting emergent adults caught indoors, outdoors and in exit traps.\ud \ud Results:\ud Proportions of inseminated females inside the experimental huts in the village increased from approximately 60% at 6 p.m. to approximately 90% the following morning despite no new mosquitoes entering the huts after 6 p.m. Insemination in the local homes increased from approximately 78% to approximately 93% over the same time points. In the semi-field observations of wild-caught captive mosquitoes, the proportions of inseminated An. funestus were 20.9% (95% confidence interval [CI]: ± 2.8) outdoors, 25.2% (95% CI: ± 3.4) indoors and 16.8% (± 8.3) in exit traps, while the proportions of inseminated An. arabiensis were 42.3% (95% CI: ± 5.5) outdoors, 47.4% (95% CI: ± 4.7) indoors and 37.1% (CI: ± 6.8) in exit traps.\ud \ud Conclusion:\ud Wild populations of An. funestus and An. arabiensis in these study villages can mate both inside and outside human dwellings. Most of the mating clearly happens before the mosquitoes enter houses, but additional mating happens indoors. The ecological significance of such indoor mating remains to be determined. The observed insemination inside the experimental huts fitted with exit traps and in the unsealed village houses suggests that the indoor mating happens voluntarily even under unrestricted egress. These findings may inspire improved vector control, such as by targeting males indoors, and potentially inform alternative methods for colonizing strongly eurygamic Anopheles species (e.g. An. funestus) inside laboratories or semi-field chambers.

Published
2021

16. Additional file 1 of Wild populations of malaria vectors can mate both inside and outside human dwellings

Author

Nambunga, Ismail H., Msugupakulya, Betwel J., Hape, Emmanuel E., Mshani, Issa H., Kahamba, Najat F., Mkandawile, Gustav, Mabula, Daniel M., Njalambaha, Rukiyah M., Kaindoa, Emmanuel W., Muyaga, Letus L., Hermy, Marie R. G., Tripet, Frederic, Ferguson, Heather M., Ngowo, Halfan S., and Okumu, Fredros O.

Subjects
fungi, parasitic diseases
Abstract

Additional file 1. Male mosquitoes in different house categories and collection time.

Published
2021
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20. Wild Populations of Malaria Vectors Can Mate Both Inside and Outside Human Dwellings

Author

Nambunga, Ismail H., primary, Msugupakulya, Betwel J., additional, Hape, Emmanuel E., additional, Mshani, Issa H., additional, Kahamba, Najat F., additional, Mkandawile, Gustav, additional, Mabula, Daniel M., additional, Njalambaha, Rukiyah M., additional, Kaindoa, Emmanuel W., additional, Muyaga, Letus L., additional, Hermy, Marie R. G., additional, Tripet, Frederic, additional, Ferguson, Heather, additional, Ngowo, Halfan S., additional, and Okumu, Fredros O., additional

Published
2021
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21. Addressing Key Gaps in Implementation of Mosquito Larviciding to Accelerate Malaria Vector Control in Southern Tanzania: Results of a Stakeholder Engagement Process in Local District Councils

Author

Mapua, Salum Abdallah, primary, Finda, Marceline F., additional, Nambunga, Ismail H., additional, Msugupakulya, Betwel J., additional, Ukio, Kusirye, additional, Chaki, Prosper P., additional, Tripet, Frederic, additional, Kelly, Ann H., additional, Christofides, Nicola, additional, Lezaun, Javier, additional, and Okumu, Fredros O., additional

Published
2020
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22. Aquatic habitats of the malaria vector, Anopheles funestus in rural south-eastern Tanzania

Author

Nambunga, Ismail Hassani, primary, Ngowo, Halfan S., additional, Mapua, Salum A., additional, Hape, Emmanuel E., additional, Msugupakulya, Betwel J., additional, Msaky, Dickson S., additional, Mhumbira, Nicolaus T., additional, Mchwembo, Karim R., additional, Tamayamali, Gerald Z., additional, Mlembe, Slyakus V., additional, Njalambaha, Rukiyah M., additional, Lwetoijera, Dickson W., additional, Finda, Marceline F., additional, Govella, Nicodem J., additional, Matoke-Muhia, Damaris, additional, Kaindoa, Emmanuel W., additional, and Okumu, Fredros O., additional

Published
2020
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23. Discovery of knock-down resistance in the major African malaria vector Anopheles funestus .

Author

Odero JO, Dennis TPW, Polo B, Nwezeobi J, Boddé M, Nagi SC, Hernandez-Koutoucheva A, Nambunga IH, Bwanary H, Mkandawile G, Govella NJ, Kaindoa EW, Ferguson HM, Ochomo E, Clarkson CS, Miles A, Lawniczak MKN, Weetman D, Baldini F, and Okumu FO

Abstract

A major mechanism of insecticide resistance in insect pests is knock-down resistance ( kdr ) caused by mutations in the voltage-gated sodium channel ( Vgsc ) gene. Despite being common in most malaria Anopheles vector species, kdr mutations have never been observed in Anopheles funestus , the principal malaria vector in Eastern and Southern Africa. While monitoring 10 populations of An. funestus in Tanzania, we unexpectedly found resistance to DDT, a banned insecticide, in one location. Through whole-genome sequencing of 333 An. funestus samples from these populations, we found 8 novel amino acid substitutions in the Vgsc gene, including the kdr variant, L976F (L1014F in An. gambiae ), in tight linkage disequilibrium with another (P1842S). The mutants were found only at high frequency in one region, with a significant decline between 2017 and 2023. Notably, kdr L976F was strongly associated with survivorship to the exposure to DDT insecticide, while no clear association was noted with a pyrethroid insecticide (deltamethrin). Further study is necessary to identify the origin and spread of kdr in An. funestus , and the potential threat to current insecticide-based vector control in Africa., Competing Interests: Competing interests The authors declare no competing interests.

Published
2024
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