Efficacy of two PBO long lasting insecticidal nets against natural populations of Anopheles gambiae s.l. in experimental huts, Kolokopé, Togo

Ketoh, Guillaume Koffivi; Ahadji-Dabla, Koffi Mensah; Chabi, Joseph; Amoudji, Adjovi D.; Apétogbo, Georges Yawo; Awokou, Fantchè; Glitho, Isabelle Adolé

doi:10.1371/journal.pone.0192492

Cited by 25 publications

(38 citation statements)

References 19 publications

(21 reference statements)

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“…However, next generation LLINs either impregnated with pyrethroids and the synergist PBO or containing chlorfenapyr (Interceptor G2 ® ) are potential alternatives for the improved efficacy of LLINs and for resistance management. Several experimental hut studies have shown improved efficacy of PBO and chlorfenapyr LLINs in controlling pyrethroid resistant malaria vectors compared to conventional pyrethroid LLINs [53][54][55][56][57]. LLINs containing PBO or novel insecticide classes should be considered by the NMCP of DR Congo for future LLIN distribution campaigns in areas of moderate to high intensity of pyrethroid resistance, although the costs of these nets would also need to be considered.…”

Section: Discussionmentioning

confidence: 99%

Intensity of pyrethroid resistance in Anopheles gambiae before and after a mass distribution of insecticide-treated nets in Kinshasa and in 11 provinces of the Democratic Republic of Congo

Watsenga

Agossa

Manzambi

et al. 2020

Malar J

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Background: Between 2011 and 2018, an estimated 134.8 million pyrethroid-treated long-lasting insecticidal nets (LLINs) were distributed nationwide in the Democratic Republic of Congo (DRC) for malaria control. Pyrethroid resistance has developed in DRC in recent years, but the intensity of resistance and impact on LLIN efficacy was not known. Therefore, the intensity of resistance of Anopheles gambiae sensu lato (s.l.) to permethrin and deltamethrin was monitored before and after a mass distribution of LLINs in Kinshasa in December 2016, and in 6 other sites across the country in 2017 and 11 sites in 2018. Methods: In Kinshasa, CDC bottle bioassays using 1, 2, 5, and 10 times the diagnostic dose of permethrin and deltamethrin were conducted using An. gambiae s.l. collected as larvae and reared to adults. Bioassays were conducted in four sites in Kinshasa province 6 months before a mass distribution of deltamethrin-treated LLINs and then two, six, and 10 months after the distribution. One site in neighbouring Kongo Central province was used as a control (no mass campaign of LLIN distribution during the study). Nationwide intensity assays were conducted in six sites in 2017 using CDC bottle bioassays and in 11 sites in 2018 using WHO intensity assays. A sub-sample of An. gambiae s.l. was tested by PCR to determine species composition and frequency of kdr-1014F and 1014S alleles. Results: In June 2016, before LLIN distribution, permethrin resistance intensity was high in Kinshasa; the mean mortality rate was 43% at the 5× concentration and 73% at the 10× concentration. Bioassays at 3 time points after LLIN distribution showed considerable variation by site and time and there was no consistent evidence for an increase in pyrethroid resistance intensity compared to the neighbouring control site. Tests of An. gambiae s.l. in 6 sites across the country in 2017 and 11 sites in 2018 showed all populations were resistant to the diagnostic doses of 3 pyrethroids. In 2018, the intensity of resistance varied by site, but was generally moderate for all three pyrethroids, with survivors at

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Section: Discussionmentioning

confidence: 99%

Intensity of pyrethroid resistance in Anopheles gambiae before and after a mass distribution of insecticide-treated nets in Kinshasa and in 11 provinces of the Democratic Republic of Congo

Watsenga

Agossa

Manzambi

et al. 2020

Malar J

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“…gambiae s.l. have been conducted in several areas of Togo and showed high level of pyrethroid resistance at Kolokopé (Ketoh et al 2018, Amoudji et al 2019 or surroundings (Djègbè et al 2018). This study reports high pyrethroid intensity resistance in An.…”

Section: Discussionmentioning

confidence: 64%

“…PBO+deltamethrin and PBO+permethrin incorporated, respectively (Ketoh et al 2018). Also, a study by Dadzie et al (2017) in Ghana, reported the role of PBO in enhancing the efficacy of pyrethroid insecticides against An.…”

Section: Discussionmentioning

confidence: 99%

“…Farming activities are the main source of revenue of the population and specifically cotton cultivation with approximately 236 hectares of land and an estimated production of 1000 tons per year. Huge quantity of insecticides are used in the area for crop protection (CRA-SH 2012), and resistance to deltamethrin and permethrin has been recently reported in the area (Ketoh et al 2018).…”

Section: Study Sitementioning

confidence: 99%

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Pyrethroid Resistance Intensity ofAnopheles gambiae sensu lato(Diptera: Culicidae) from Phase II Hut Trial Station in KOLOKOPE, Eastern Plateau Togo: A Potential Site to Assess the Next Generation of Long-Lasting Insecticidal Nets

Ahadji-Dabla

Chabi

Apétogbo

et al. 2020

Preprint

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Per WHO recommendations, the implementation of the next-generation of Long Lasting Insecticidal Nets (LLINs) for malaria vector control requires appropriate investigations on the insecticide resistance profile of the vector and the impact of the LLINs on the known resistant mosquitoes. The next-generation of LLINs are actually an incorporation of a mixture of pyrethroid insecticides and a synergist such as PBO. Several studies have proven the additional impact of PBO on the increase in the mortality rate of Anopheles gambiae s.l. (Diptera: Culicidae). However, further assessments need to be done at community level in order to set a stage for the acceleration of the WHO policies on the implementation of the next-generation of LLINs. Kolokope is a cotton-growing area in the central region of Togo characterized by an intensive use of agro pesticides and insecticides. A phase II experimental hut station for the evaluation of mosquito control tools has been built in Kolokope. For the characterization of the site, WHO susceptibility tests using diagnostic doses of eight insecticides, PBO synergist assay and intensity assay of three pyrethroids (5x and 10x) were conducted on adult female mosquitoes obtained from larvae collected around the site. Anopheles gambiae s.l. from Kolokope showed high resistance to pyrethroids and DDT, but in lesser extent to carbamates and organophosphates. Likewise, high intensity of resistance to pyrethroid was observed with less than 40% mortality at 10x deltamethrin, 52 and 29% mortality at 10x permethrin and 10x alphacypermethrin, respectively. Also, the addition of PBO showed a reversal mortality which was similar to mortality rate at 10x doses of pyrethroids. The high pyrethroid intensity resistance recorded at Kolokope could be mainly due to the pressure on An. gambiae s.l. through the excessive use of insecticide in agriculture. This can be used for the assessment of the next-generation of LLINs either in experimental hut or at a community trial.

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“…A practical example of the effect of combining insecticides with synergists, is the increased pyrethroid-susceptibility that was observed when pyrethroids were combined with PBO [23]. In a study by Ketoh et al [233], higher mortality rates and reduced blood-feeding were observed in mosquitoes that were exposed to pyrethroid-treated nets with PBO compared to those exposed to pyrethroid only treated nets. PBO inhibits cytochrome P450 enzymes, which are key players in insecticide resistance, it also increases cuticular penetration of insecticides [233].…”

Section: Combining Insecticide With Synergistsmentioning

confidence: 99%

Anopheles metabolic proteins in malaria transmission, prevention and control: a review

et al. 2020

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The increasing resistance to currently available insecticides in the malaria vector, Anopheles mosquitoes, hampers their use as an effective vector control strategy for the prevention of malaria transmission. Therefore, there is need for new insecticides and/or alternative vector control strategies, the development of which relies on the identification of possible targets in Anopheles. Some known and promising targets for the prevention or control of malaria transmission exist among Anopheles metabolic proteins. This review aims to elucidate the current and potential contribution of Anopheles metabolic proteins to malaria transmission and control. Highlighted are the roles of metabolic proteins as insecticide targets, in blood digestion and immune response as well as their contribution to insecticide resistance and Plasmodium parasite development. Furthermore, strategies by which these metabolic proteins can be utilized for vector control are described. Inhibitors of Anopheles metabolic proteins that are designed based on target specificity can yield insecticides with no significant toxicity to non-target species. These metabolic modulators combined with each other or with synergists, sterilants, and transmission-blocking agents in a single product, can yield potent malaria intervention strategies. These combinations can provide multiple means of controlling the vector. Also, they can help to slow down the development of insecticide resistance. Moreover, some metabolic proteins can be modulated for mosquito population replacement or suppression strategies, which will significantly help to curb malaria transmission.

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Efficacy of two PBO long lasting insecticidal nets against natural populations of Anopheles gambiae s.l. in experimental huts, Kolokopé, Togo

Cited by 25 publications

References 19 publications

Intensity of pyrethroid resistance in Anopheles gambiae before and after a mass distribution of insecticide-treated nets in Kinshasa and in 11 provinces of the Democratic Republic of Congo

Intensity of pyrethroid resistance in Anopheles gambiae before and after a mass distribution of insecticide-treated nets in Kinshasa and in 11 provinces of the Democratic Republic of Congo

Pyrethroid Resistance Intensity ofAnopheles gambiae sensu lato(Diptera: Culicidae) from Phase II Hut Trial Station in KOLOKOPE, Eastern Plateau Togo: A Potential Site to Assess the Next Generation of Long-Lasting Insecticidal Nets

Anopheles metabolic proteins in malaria transmission, prevention and control: a review

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