Exposure to the insecticide-treated bednet PermaNet 2.0 reduces the longevity of the wild African malaria vector Anopheles funestus but GSTe2-resistant mosquitoes live longer

Tchakounte, Ange; Tchouakui, Magellan; Mu-Chun, Chiang; Tchapga, Williams; Kopia, Edmond; Soh, Patrice Takam; Njiokou, Flobert; Riveron, Jacob M.; Wondji, Charles S.

doi:10.1371/journal.pone.0213949

Cited by 26 publications

(31 citation statements)

References 38 publications

(43 reference statements)

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“…The multiple insecticide resistance patterns observed in the An. funestus s.s. population to pyrethroids and DDT in Elende corresponds to the trends observed in Gounougou (2012) [9] and higher than in Obout (2016) [44] but lower than in Tibati (2018) [34]. Moreover, the high resistance pattern of An.…”

Section: Multiple and High Insecticide Resistance In Both Major Vectosupporting

confidence: 68%

“…However, this result is similar to mortality rate recorded in An. funestus s.s. from Obout that exhibited very high level of resistance to dieldrin (4.35% mortality rate) [44]. This high frequency could be as a result of strong resistance selection due to environmental persistence of insecticide residues since its withdrawal from public and agricultural use in Cameroon.…”

Section: Elevated Metabolic Resistance In An Funestus Differs With Hmentioning

confidence: 99%

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Elevated Plasmodium infection and multiple insecticide resistance in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the airport of Yaoundé, the Capital city of Cameroon

Nongley¹,

Mbugulize²,

Terence³

et al. 2020

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Background Reducing the burden of malaria requires better understanding of vector populations particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the international airport of Yaoundé, the capital city of Cameroon, including species composition, abundance, Plasmodium infection rate; insecticide resistance profiles and underlying resistance mechanisms. Methods Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a village located 2km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adult progeny. WHO bioassays were performed to assess resistance profile to insecticides. The threshold of insecticide susceptibility was fixed above 98% mortality rate and mortality rates below 90% were considered indicative of confirmed insecticide resistance according to the WHO test procedures for insecticide resistance monitoring. Furthermore, the molecular basis of resistance and Plasmodium infection rates were investigated.Results Anopheles funestus s.s. was most abundant species in Elende (85%) followed by Anopheles gambiae s.s. (15%) with both having a similar sporozoite infection rate. Both species exhibited high levels of resistance to pyrethroids (<40% mortality). An. gambiae s.s. was also resistant to DDT (9.9% mortality) and bendiocarb (54% mortality) while susceptible to organophosphate. An. funestus s.s. was resistant to dieldrin (1% mortality), DDT (86% mortality) but susceptible to carbamates and organophosphates. The DDT/pyrethroid L119F-GSTe2 resistance allele (8%) and G119S ace -1 resistance allele (15%) were detected in An. funestus s.s. and An. gambiae s.s. respectively. Furthermore, the high pyrethroid/DDT resistances in An. gambiae s.s. corresponded with an increase frequency of 1014F kdr allele (95%). The CYP6P9a P450 resistance allele was absent in the An. funestus s.s. population meanwhile transcriptional profiling of candidate cytochrome P450 genes reveals the over-expression of CYP6P5 , CYP6P9a and CYP6P9b. Conclusion The resistance to multiple insecticide classes observed in these vector populations alongside the high Plasmodium infection rate highlights the challenges that public health vector control programs encounter in sustaining the regular effectiveness of contemporary insecticide-based control interventions in forested areas. More particularly, the resistance observed against the carbamates and possible resistance against the organophosphates constitutes a major concern for IRS.

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Section: Multiple and High Insecticide Resistance In Both Major Vectosupporting

confidence: 68%

Section: Elevated Metabolic Resistance In An Funestus Differs With Hmentioning

confidence: 99%

Elevated Plasmodium infection and multiple insecticide resistance in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the airport of Yaoundé, the Capital city of Cameroon

Nongley¹,

Mbugulize²,

Terence³

et al. 2020

Preprint

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“…Females that were exposed to deltamethrin fed less than females that were not exposed. Our findings were consistent with Glunt et al, [26] and contrary to what was observed by Tchakounte et al, [27] who showed that exposure of mosquitoes to PermaNet 2.0 deltamethrintreated bednet presented no effect of on their blood feeding ability. From an epidemiological point of view, our findings can be translated into a reduction in transmission as the drop in the rate of mosquito bites also means less risk of infection with plasmodium.…”

Section: Discussionsupporting

confidence: 93%

Impact of sublethal pyrethroid exposure on resistant Anopheles gambiae mosquitoes’ fitness

Kropf

Fodjo

Zoh

et al. 2020

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Background : There is increasing evidence of insecticide resistance spreading among wild mosquito populations, which is widely believed to compromise vector control once it reaches a threshold that enables mosquitoes to survive exposure to long lasting treated bed-net (LLIN) or indoor residual spraying (IRS). However, very little is known about the long-term impact of insecticide resistance on malaria transmission, which makes the consequence of insecticide resistance spreading difficult to predict. Methods: To gain more clarity, we have assessed five life-history traits of a resistant Anopheles gambiae laboratory strain that was repeatedly exposed to a LLIN and compared with individuals issued from the same strain but exposed to an untreated bed-net. Results: The non-parametric Kruskal-Wallis test did not show any significant impact of gonotrophic cycle on the five traits. However, the Kolmogorov-Smirnov non-parametric test revealed a significant (i) drop in blood feeding mean rates (D = 0.800; P< 0.0001), (ii) increase in 24-hours post-exposure (D = 0.600; P< 0.001) and (iii) end of gonotrophic cycle mortality (D = 0.611; P <0.006), and (iv) drop in egg laying rate (D = 0.730, P< 0.0001) when mosquitoes were exposed. Surprisingly, there was rather an upward trend in the number of L3 larvae/female mosquito for the exposed group comparing to the unexposed one, although the difference was not significant (D = 0.417, P> 0.05). Conclusion: Our study shows that in a context of widespread of resistance to insecticides, current pyrethroid-based vector control tools can still confer protection against malaria.

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“…PermaNet® 2.0 has been among the most widely distributed LLIN brand in the recent decade and bioefficacy studies have been conducted in several countries. Most of these studies used LLINs dating back to 2012 and before, and showed very good bioefficacy of PermaNet® 2.0 [25][26][27][28][29]. In tests conducted in an African setting (Northern Tanzania), PermaNet® 2.0 from 2017 were reported to fulfil all requirements [30].…”

Section: Discussionmentioning

confidence: 99%

Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea

Vinit

Timinao

Bubun

et al. 2020

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Background: Papua New Guinea (PNG) has the highest malaria transmission outside of Africa and long-lasting insecticidal nets (LLIN) are the only vector-control tool distributed country-wide. LLIN were introduced into PNG in about 2005 and have been attributed to have had a huge impact on malaria transmission, with reductions in malaria prevalence observed from 15.7% (2008) to 1% (2014). Since 2015, malaria indicators in PNG have risen significantly. Similar trends have been observed in several African nations. In the present study, we observed a drastic reduction in bioefficacy of LLIN collected both from communities (used nets) and prior to use (new nets). We hypothesise that decreased bioefficacy of LLINs is a major contributor to the observed malaria resurgence in PNG and possibly in other parts of the world. Methods: New LLIN in original and unopened packaging (n=192) with a range of manufacturing dates from 2007-2019 were collected either directly from consignments or from households in 15 PNG provinces. Used LLIN (n=40) were collected in 2 provinces, with manufacturing dates ranging from 2008-2017. LLIN were subjected to standard WHO cone bioassays using fully susceptible An. farauti mosquitoes. A subset of LLIN was re-tested using fully susceptible An. gambiae mosquitoes in order to ensure reproducibility of results. Results: Only 7% (95% CI 4-12%) of new LLIN manufactured between 2013-2019 exhibited 100% mortality. However, 84% (95%CI: 65-84%) new nets manufactured in 2012 or before exhibited 100% mortality. Only 29 % of used LLIN less than 3 years old exhibited > 80% 24h-mortality. Results obtained in tests using An. farauti corresponded well with confirmatory tests conducted using An. gambiae. Discussion: Bioefficacy of LLIN in PNG appears to have been highly variable since 2013, with few nets manufactured since 2013 meeting WHO standards. This time-frame coincides with malaria resurgence in the country. These results may have ramifications for LLIN-based malaria control that go beyond the local PNG scenario.

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Exposure to the insecticide-treated bednet PermaNet 2.0 reduces the longevity of the wild African malaria vector Anopheles funestus but GSTe2-resistant mosquitoes live longer

Cited by 26 publications

References 38 publications

Elevated Plasmodium infection and multiple insecticide resistance in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the airport of Yaoundé, the Capital city of Cameroon

Elevated Plasmodium infection and multiple insecticide resistance in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the airport of Yaoundé, the Capital city of Cameroon

Impact of sublethal pyrethroid exposure on resistant Anopheles gambiae mosquitoes’ fitness

Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea

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