Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal.
<h4>Background</h4>Visceral leishmaniasis (VL) is targeted for elimination as a public health problem in Nepal by 2023. For nearly three decades, the core vector control intervention in Nepal has been indoor residual spraying (IRS) with pyrethroids. Considering the long-term use of pyret...
Saved in:
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2022-07-01
|
| Series: | PLoS Neglected Tropical Diseases |
| Online Access: | https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0010304&type=printable |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849469994421714944 |
|---|---|
| author | Lalita Roy Surendra Uranw Kristien Cloots Tom Smekens Usha Kiran Uttam Raj Pyakurel Murari Lal Das Rajpal S Yadav Wim Van Bortel |
| author_facet | Lalita Roy Surendra Uranw Kristien Cloots Tom Smekens Usha Kiran Uttam Raj Pyakurel Murari Lal Das Rajpal S Yadav Wim Van Bortel |
| author_sort | Lalita Roy |
| collection | DOAJ |
| description | <h4>Background</h4>Visceral leishmaniasis (VL) is targeted for elimination as a public health problem in Nepal by 2023. For nearly three decades, the core vector control intervention in Nepal has been indoor residual spraying (IRS) with pyrethroids. Considering the long-term use of pyrethroids and the possible development of resistance in the vector Phlebotomus argentipes sand flies, we monitored the susceptibility status of their field populations to the insecticides of different classes, in villages with and without IRS activities in recent years.<h4>Methodology/principal findings</h4>Sand flies were collected from villages with and without IRS in five VL endemic districts from August 2019 to November 2020. The WHO susceptibility test procedure was adopted using filter papers impregnated at the discriminating concentrations of insecticides of the following classes: pyrethroids (alpha-cypermethrin 0.05%, deltamethrin 0.05%, and lambda-cyhalothrin 0.05%), carbamates (bendiocarb 0.1%) and organophosphates (malathion 5%). Pyrethroid resistance intensity bioassays with papers impregnated with 5× of the discriminating concentrations, piperonyl butoxide (PBO) synergist-pyrethroid bioassays, and DDT cross-resistance bioassays were also performed. In the IRS villages, the vector sand flies were resistant (mortality rate <90%) to alpha-cypermethrin and possibly resistant (mortality rate 90-97%) to deltamethrin and lambda-cyhalothrin, while susceptibility to these insecticides was variable in the non-IRS villages. The vector was fully susceptible to bendiocarb and malathion in all villages. A delayed knockdown time (KDT50) with pyrethroids was observed in all villages. The pyrethroid resistance intensity was low, and the susceptibility improved at 5× of the discriminating concentrations. Enhanced pyrethroid susceptibility after pre-exposure to PBO and the DDT-pyrethroid cross-resistance were evident.<h4>Conclusions/significance</h4>Our investigation showed that P. argentipes sand flies have emerged with pyrethroid resistance, suggesting the need to switch to alternative classes of insecticides such as organophosphates for IRS. We strongly recommend the regular and systematic monitoring of insecticide resistance in sand flies to optimize the efficiency of vector control interventions to sustain VL elimination efforts in Nepal. |
| format | Article |
| id | doaj-art-2d9f0b4ce6f74363b28885560338d5df |
| institution | Kabale University |
| issn | 1935-2727 1935-2735 |
| language | English |
| publishDate | 2022-07-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Neglected Tropical Diseases |
| spelling | doaj-art-2d9f0b4ce6f74363b28885560338d5df2025-08-20T03:25:16ZengPublic Library of Science (PLoS)PLoS Neglected Tropical Diseases1935-27271935-27352022-07-01167e001030410.1371/journal.pntd.0010304Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal.Lalita RoySurendra UranwKristien ClootsTom SmekensUsha KiranUttam Raj PyakurelMurari Lal DasRajpal S YadavWim Van Bortel<h4>Background</h4>Visceral leishmaniasis (VL) is targeted for elimination as a public health problem in Nepal by 2023. For nearly three decades, the core vector control intervention in Nepal has been indoor residual spraying (IRS) with pyrethroids. Considering the long-term use of pyrethroids and the possible development of resistance in the vector Phlebotomus argentipes sand flies, we monitored the susceptibility status of their field populations to the insecticides of different classes, in villages with and without IRS activities in recent years.<h4>Methodology/principal findings</h4>Sand flies were collected from villages with and without IRS in five VL endemic districts from August 2019 to November 2020. The WHO susceptibility test procedure was adopted using filter papers impregnated at the discriminating concentrations of insecticides of the following classes: pyrethroids (alpha-cypermethrin 0.05%, deltamethrin 0.05%, and lambda-cyhalothrin 0.05%), carbamates (bendiocarb 0.1%) and organophosphates (malathion 5%). Pyrethroid resistance intensity bioassays with papers impregnated with 5× of the discriminating concentrations, piperonyl butoxide (PBO) synergist-pyrethroid bioassays, and DDT cross-resistance bioassays were also performed. In the IRS villages, the vector sand flies were resistant (mortality rate <90%) to alpha-cypermethrin and possibly resistant (mortality rate 90-97%) to deltamethrin and lambda-cyhalothrin, while susceptibility to these insecticides was variable in the non-IRS villages. The vector was fully susceptible to bendiocarb and malathion in all villages. A delayed knockdown time (KDT50) with pyrethroids was observed in all villages. The pyrethroid resistance intensity was low, and the susceptibility improved at 5× of the discriminating concentrations. Enhanced pyrethroid susceptibility after pre-exposure to PBO and the DDT-pyrethroid cross-resistance were evident.<h4>Conclusions/significance</h4>Our investigation showed that P. argentipes sand flies have emerged with pyrethroid resistance, suggesting the need to switch to alternative classes of insecticides such as organophosphates for IRS. We strongly recommend the regular and systematic monitoring of insecticide resistance in sand flies to optimize the efficiency of vector control interventions to sustain VL elimination efforts in Nepal.https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0010304&type=printable |
| spellingShingle | Lalita Roy Surendra Uranw Kristien Cloots Tom Smekens Usha Kiran Uttam Raj Pyakurel Murari Lal Das Rajpal S Yadav Wim Van Bortel Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. PLoS Neglected Tropical Diseases |
| title | Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. |
| title_full | Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. |
| title_fullStr | Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. |
| title_full_unstemmed | Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. |
| title_short | Susceptibility status of the wild-caught Phlebotomus argentipes (Diptera: Psychodidae: Phlebotominae), the sand fly vector of visceral leishmaniasis, to different insecticides in Nepal. |
| title_sort | susceptibility status of the wild caught phlebotomus argentipes diptera psychodidae phlebotominae the sand fly vector of visceral leishmaniasis to different insecticides in nepal |
| url | https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0010304&type=printable |
| work_keys_str_mv | AT lalitaroy susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT surendrauranw susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT kristiencloots susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT tomsmekens susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT ushakiran susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT uttamrajpyakurel susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT murarilaldas susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT rajpalsyadav susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal AT wimvanbortel susceptibilitystatusofthewildcaughtphlebotomusargentipesdipterapsychodidaephlebotominaethesandflyvectorofvisceralleishmaniasistodifferentinsecticidesinnepal |