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

2021 ◽  
Vol 6 ◽  
pp. 204
Author(s):  
Behi Kouadio Fodjo ◽  
Alida Kropf ◽  
Marius Gonse Zoh ◽  
Christabelle Gba Sadia ◽  
Affoué France-Paraudie Kouadio ◽  
...  
Keyword(s):  
Life History ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Life History Traits ◽  
Indoor Residual Spraying ◽  
Laboratory Strain ◽  
Blood Feeding ◽  
Egg Laying ◽  
Bed Net

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: Out of the five measured life-history traits, four were significantly affected by exposure to insecticides. Indeed, the Kolmogorov-Smirnov non-parametric test revealed a significant (i) drop in blood feeding mean rates (P=0.000000494), (ii) increase in 24-hours post-exposure (P= 0.000008559) and (iii) end of gonotrophic cycle mortality (P =0.0005749), and (iv) drop in egg laying rate (P=0.000107) when mosquitoes were exposed. 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

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

2020 ◽  
Author(s):  
Alida Kropf ◽  
Behi K Fodjo ◽  
Marius G Zoh ◽  
Chistabelle G Sadia ◽  
Affoué FP Kouadio ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Indoor Residual Spraying ◽  
Laboratory Strain ◽  
Blood Feeding ◽  
Egg Laying ◽  
Bed Net ◽  
Gonotrophic Cycle ◽  
Non Parametric

Abstract 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.

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

2020 ◽  
Author(s):  
Alida Kropf ◽  
Behi K Fodjo ◽  
Marius G Zoh ◽  
Chistabelle G Sadia ◽  
Affoué FP Kouadio ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Indoor Residual Spraying ◽  
Laboratory Strain ◽  
Blood Feeding ◽  
Egg Laying ◽  
Bed Net ◽  
Gonotrophic Cycle ◽  
Non Parametric

Abstract 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 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.

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

2021 ◽  
Vol 6 ◽  
pp. 204
Author(s):  
Behi Kouadio Fodjo ◽  
Alida Kropf ◽  
Marius Gonse Zoh ◽  
Christabelle Gba Sadia ◽  
Affoué France-Paraudie Kouadio ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Indoor Residual Spraying ◽  
Laboratory Strain ◽  
Blood Feeding ◽  
Egg Laying ◽  
Bed Net ◽  
Gonotrophic Cycle ◽  
Non Parametric

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 four 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.

scholarly journals Efficacy of Interceptor® G2, a new long-lasting insecticidal net against wild pyrethroid-resistant Anopheles gambiae s.s. from Côte d’Ivoire: a semi-field trial

Parasite ◽  
2018 ◽  
Vol 25 ◽  
pp. 42 ◽  
Author(s):  
Soromane Camara ◽  
Ludovic Phamien Ahoua Alou ◽  
Alphonsine Amanan Koffi ◽  
Yao Cyntia Muriel Clegban ◽  
Jean-Paul Kabran ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Blood Feeding ◽  
Phase Iii ◽  
Anopheles Gambiae S.S ◽  
Cote D’Ivoire ◽  
Côte D'ivoire

Background: The widespread insecticide resistance in malaria vector populations is a serious threat to the efficacy of vector control tools. As a result, the World Health Organization (WHO) supports the development of alternative tools that combine several insecticides with the aim of improving vector control and the management of insecticide resistance. In the present study, a long-lasting insecticidal net treated with a mixture of chlorfenapyr and alphacypermethrin was evaluated against wild pyrethroid-resistant Anopheles gambiae s.s in M’bé, Côte d’Ivoire. Centers for Disease Control and Prevention (CDC) bottle tests were carried out with resistant An. gambiae s.s. of M’bé and the susceptible strain, to assess the resistance level to chlorfenapyr and alphacypermethrin. Results: CDC bottle bioassays revealed a high level of resistance of An. gambiae s.s. population from M’bé to alphacypermethrin, whereas they revealed low resistance to chlorfenapyr. In experimental huts, Interceptor® G2 that was unwashed or washed 20 times killed 87% and 82% of An. gambiae s.s., respectively, whereas Interceptor® LN that was either unwashed or washed 20 times killed only about 10% of the mosquitoes. The blood-feeding inhibition induced by Interceptor® was not significantly different compared to untreated nets, whereas Interceptor® G2 that was unwashed or washed 20 times induced 42% and 34% inhibition of blood-feeding, respectively. Conclusion: Interceptor® G2 met the WHOPES criteria to undergo a phase III study. Investigation of its efficacy at a community level and the conduct of randomized controlled trials dealing with epidemiological outputs are warranted in order to study the potential of Interceptor® G2 to better protect communities.

scholarly journals Putative pleiotropic effects of the knockdown resistance (L1014F) allele on the life-history traits of Anopheles gambiae

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Adandé A. Medjigbodo ◽  
Luc S. Djogbénou ◽  
Oswald Y. Djihinto ◽  
Romaric B. Akoton ◽  
Emmanuella Abbey ◽  
...  
Keyword(s):  
Life History ◽  
Anopheles Gambiae ◽  
Blood Volume ◽  
Life History Traits ◽  
Blood Feeding ◽  
Malaria Vectors ◽  
Resistance Allele ◽  
Knockdown Resistance ◽  
Feeding Success ◽  
The Mean

Abstract Background Existing mechanisms of insecticide resistance are known to help the survival of mosquitoes following contact with chemical compounds, even though they could negatively affect the life-history traits of resistant malaria vectors. In West Africa, the knockdown resistance mechanism kdrR (L1014F) is the most common. However, little knowledge is available on its effects on mosquito life-history traits. The fitness effects associated with this knockdown resistance allele in Anopheles gambiae sensu stricto (s.s.) were investigated in an insecticide-free laboratory environment. Methods The life-history traits of Kisumu (susceptible) and KisKdr (kdr resistant) strains of An. gambiae s.s. were compared. Larval survivorship and pupation rate were assessed as well as fecundity and fertility of adult females. Female mosquitoes of both strains were directly blood fed through artificial membrane assays and then the blood-feeding success, blood volume and adult survivorship post-blood meal were assessed. Results The An. gambiae mosquitoes carrying the kdrR allele (KisKdr) laid a reduced number of eggs. The mean number of larvae in the susceptible strain Kisumu was three-fold overall higher than that seen in the KisKdr strain with a significant difference in hatching rates (81.89% in Kisumu vs 72.89% in KisKdr). The KisKdr larvae had a significant higher survivorship than that of Kisumu. The blood-feeding success was significantly higher in the resistant mosquitoes (84%) compared to the susceptible ones (34.75%). However, the mean blood volume was 1.36 µL/mg, 1.45 µL/mg and 1.68 µL/mg in Kisumu, homozygote and heterozygote KisKdr mosquitoes, respectively. After blood-feeding, the heterozygote KisKdr mosquitoes displayed highest survivorship when compared to that of Kisumu. Conclusions The presence of the knockdown resistance allele appears to impact the life-history traits, such as fecundity, fertility, larval survivorship, and blood-feeding behaviour in An. gambiae. These data could help to guide the implementation of more reliable strategies for the control of malaria vectors.

scholarly journals Molecular Detection of Insecticide Resistance Mutations in Anopheles gambiae from Sierra Leone Using Multiplex SNaPshot and Sequencing

2021 ◽  
Vol 11 ◽  
Author(s):  
Jianhai Yin ◽  
Frederick Yamba ◽  
Canjun Zheng ◽  
Shuisen Zhou ◽  
Samuel Juana Smith ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Sierra Leone ◽  
Statistical Significance ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Mosquito Vector ◽  
Resistance Mutations ◽  
African Countries

Vector control interventions including long-lasting insecticidal nets and indoor residual spraying are important for malaria control and elimination. And effectiveness of these interventions depends entirely on the high level of susceptibility of malaria vectors to insecticides. However, the insecticide resistance in majority of mosquito vector species across African countries is a serious threat to the success of vector control efforts with the extensive use of insecticides, while no data on insecticide resistance was reported from Sierra Leone in the past decade. In the present study, the polymerase chain reaction was applied for the identification of species of 757 dry adult female Anopheles gambiae mosquitoes reared from larvae collected from four districts in Sierra Leone during May and June 2018. And the mutations of kdr, rdl, ace-1 genes in An. gambiae were detected using SNaPshot and sequencing. As a result, one sample from Western Area Rural district belonged to Anopheles melas, and 748 An. gambiae were identified. Furthermore, the rdl mutations, kdr west mutations and ace-1 mutation were found. The overall frequency was 35.7%, 0.3%, 97.6% and 4.5% in A296G rdl, A296S rdl, kdrW and ace-1, respectively. The frequencies of A296G rdl mutation (P &lt; 0.001), kdrW mutation (P = 0.001) and ace-1 mutation (P &lt; 0.001) were unevenly distributed in four districts, respectively, while no statistical significance was found in A296S rdl mutation (P = 0.868). In addition, multiple resistance patterns were also found. In conclusion, multiple mutations involved in insecticide resistance in An. gambiae populations in Sierra Leone were detected in the kdrW, A296G rdl and ace-1 alleles in the present study. It is necessary to monitor vector susceptibility levels to insecticides used in this country, and update the insecticide resistance monitoring and management strategy.

scholarly journals Insecticide resistance status of malaria vectors Anopheles gambiae (s.l.) of southwest Burkina Faso and residual efficacy of indoor residual spraying with microencapsulated pirimiphos-methyl insecticide

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Dieudonné Diloma Soma ◽  
Barnabas Zogo ◽  
Domonbabele François de Sales Hien ◽  
Aristide Sawdetuo Hien ◽  
Didier Alexandre Kaboré ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Burkina Faso ◽  
Anopheles Gambiae ◽  
Local Population ◽  
Residual Activity ◽  
Indoor Residual Spraying ◽  
Susceptible Strain ◽  
Malaria Vectors ◽  
Pirimiphos Methyl ◽  
Residual Efficacy

Abstract Background The rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial (RCT) was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. Methods We measured the susceptibility of the Anopheles gambiae (s.l.) population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae (s.l.) population. Results An. gambiae (s.l.) from Diébougou was resistant to DDT, pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR = 0.792, [0.55–1.12], Tukey’s test p-value = 0.19). Conclusions If data on malaria transmission and malaria cases (as measured trough the RCT) are consistent with data on residual activity of pirimiphos-methyl regardless of the type of wall, one round of IRS with pirimiphos-methyl would have the potential to control malaria in a context of multi-resistant An. gambiae (s.l.) for at least 7 months.

scholarly journals Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Pauline Winnie Orondo ◽  
Steven G. Nyanjom ◽  
Harrysone Atieli ◽  
John Githure ◽  
Benyl M. Ondeto ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Crop Protection ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Western Kenya ◽  
Animal Protection ◽  
Selection Of ◽  
Selection Of Resistance

Abstract Background Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. Methods The study was carried out in 2018–2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. Results Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8–84% to 83.3–78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1–16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. Conclusion Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides. Graphic abstract

scholarly journals Plasmodium infection decreases fecundity and increases survival of mosquitoes

2012 ◽  
Vol 279 (1744) ◽  
pp. 4033-4041 ◽  
Author(s):  
J. Vézilier ◽  
A. Nicot ◽  
S. Gandon ◽  
A. Rivero
Keyword(s):  
Life History ◽  
Insecticide Resistance ◽  
Life History Traits ◽  
Experimental System ◽  
Adaptive Strategy ◽  
Genetic Variations ◽  
The Other ◽  
Plasmodium Infection ◽  
Trade Off ◽  
The One

Long-lived mosquitoes maximize the chances of Plasmodium transmission. Yet, in spite of decades of research, the effect of Plasmodium parasites on mosquito longevity remains highly controversial. On the one hand, many studies report shorter lifespans in infected mosquitoes. On the other hand, parallel (but separate) studies show that Plasmodium reduces fecundity and imply that this is an adaptive strategy of the parasite aimed at redirecting resources towards longevity. No study till date has, however, investigated fecundity and longevity in the same individuals to see whether this prediction holds. In this study, we follow for both fecundity and longevity in Plasmodium- infected and uninfected mosquitoes using a novel, albeit natural, experimental system. We also explore whether the genetic variations that arise through the evolution of insecticide resistance modulate the effect of Plasmodium on these two life-history traits. We show that (i) a reduction in fecundity in Plasmodium- infected mosquitoes is accompanied by an increase in longevity; (ii) this increase in longevity arises through a trade-off between reproduction and survival; and (iii) in insecticide-resistant mosquitoes, the slope of this trade-off is steeper when the mosquito is infected by Plasmodium (cost of insecticide resistance).

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