scholarly journals Bioefficacy of local Lantana camara (Verberneae) plant extracts against the 3rd instar larva and adult stages of Anopheles gambiae senso lato (Giles).

2020 ◽  
Vol 3 (12) ◽  
pp. 1120-1129
Author(s):  
Wenceslas Yana ◽  
Enda Corinna Andu ◽  
Katamssadan Haman Tofel ◽  
Abe Henri
Keyword(s):  
Anopheles Gambiae ◽  
Aqueous Extract ◽  
Exposure Time ◽  
Larval Mortality ◽  
Acetone Extract ◽  
Lantana Camara ◽  
Hexane Extract ◽  
Lethal Concentration ◽  
Malaria Vectors ◽  
Malaria Vector Control

Resistance of malaria vectors to synthetic chemicals with high operational cost and environmental pollution has been a great challenge to scientists. Alternative approaches such as the use of natural plant products which are environmentally friendly are put in place to control malaria vectors. This study was focused on testing the effectiveness of three solvent extracts of Lantana camara on the 3rd instar larvae and adults of Anopheles gambiae s. l. These extracts were obtained by maceration. Bioassays test were carried out by WHO’s method for determination of larvicidal and adulticidal efficacy. The results show that, larval mortality increased significantly with the concentration and exposure time. Lethal concentrations 50 (LC50) and 95 (LC95) after 24 hours of larvae exposure time are respectively 0.31 g/mL and 1.53 g/mL  while within 48 h they are 0.27 g/mL and 0.79 g/mL for hexane extract; 1.45 g/mL and 2.0 g/mL (24 h exposure), 0.84 g/mL and 1.55 g/mL (48 h exposure) for acetone extract; 1.96 g/mL and no lethal concentration causing 95% mortality was determined; 0.40 g/mL and 2.20 g/mL (48 h) for aqueous extract. The efficacy of hexane and aqueous extract on the adult knock down and mortality were not significant even with the increasing extract concentrations and exposure time whereas with acetone extract,  the adult LC50 after 24 h was 2.4 g/mL but with 95% mortality lethal concentration was not determined. According to the results, hexane extract showed high larvicidal efficacy of An. gambiae and acetone extract showed significant adult mortality. Those two extracts of L. camara can be used to fight against An. gambiae as alternative malaria vector control to replace conventional insecticides.

scholarly journals Potential Metabolic Resistance Mechanisms to Ivermectin in Anopheles Gambiae: A Synergist Bioassay Study

2020 ◽  
Author(s):  
Patricia Nicolas ◽  
Caroline Kiuru ◽  
Martin Wagah ◽  
Martha Muturi ◽  
Urs Duthaler ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Anopheles Gambiae ◽  
Control Strategies ◽  
Resistance Mechanisms ◽  
World Health ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Cytochrome P450 Enzymes ◽  
Metabolic Resistance ◽  
Active Efflux

Abstract Background Despite remarkable success obtained with current malaria vector control strategies in the last 15 years, additional innovative measures will be needed to achieve the ambitious goals set for 2030 by the World Health Organization (WHO). New tools will need to address insecticide resistance and residual transmission as key challenges. Endectocides such as ivermectin are drugs that kill mosquitoes which feed on treated subjects. Mass administration of ivermectin can effectively target outdoor and early biting vectors, complementing the still effective conventional tools. Although this approach has garnered attention, development of ivermectin resistance is a potential pitfall. Herein, we evaluate the potential role of xenobiotic pumps and cytochrome P450 enzymes in protecting mosquitoes against ivermectin by active efflux and metabolic detoxification, respectively. Methods We determined the lethal-concentration 50 for ivermectin in colonized Anopheles gambiae, then we used chemical inhibitors and inducers of xenobiotic pumps and cytochrome P450 enzymes in combination with ivermectin to probe the mechanism of ivermectin detoxification. Results Dual inhibition of xenobiotic pumps and cytochromes have a synergistic effect with ivermectin, greatly increasing mosquito mortality. Inhibition of xenobiotic pumps alone had no effect on ivermectin-induced mortality. Induction of xenobiotic pumps and cytochromes may confer partial protection from ivermectin.Conclusion there is a clear pathway for development of ivermectin resistance in malaria vectors. Detoxification mechanisms mediated by cytochrome P450 enzymes are more important than xenobiotic pumps in protecting mosquitoes against ivermectin.

scholarly journals Characterization of resistance profile (intensity and mechanisms) of Anopheles gambiae in three communes of northern Benin, West Africa

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Casimir Dossou Kpanou ◽  
Hermann W. Sagbohan ◽  
Fortuné Dagnon ◽  
Germain G. Padonou ◽  
Razaki Ossè ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
High Intensity ◽  
Mortality Rates ◽  
Detoxification Enzymes ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Biochemical Tests ◽  
Diagnostic Dose

Abstract Background The selection and the spread of insecticide resistance in malaria vectors to the main classes of insecticides used in vector control tools are a major and ongoing challenge to malaria vector control programmes. This study aimed to determine the intensity of vector resistance to insecticides in three regions of Benin with different agro-ecological characteristics. Methods Larvae of Anopheles gambiae sensu lato (s.l.) were collected from September to November 2017 in different larval sites in three northern Benin communes: Parakou, Kandi and Malanville. Two to five-day-old, non-blood-fed, female mosquitoes were exposed to papers impregnated with deltamethrin, permethrin and bendiocarb at dosages of 1 × the diagnostic dose, 5 × and 10 × to determine the intensity of resistance in these vectors. Molecular frequencies of the kdr L1014F and ace-1R G119S insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled at each study site. Results Resistance to pyrethroids (permethrin and deltamethrin) was recorded in all three communes with mortality rates below 60% using the diagnostic dose (1x). The results obtained after exposure of An. gambiae to permethrin 10 × were 99% in Kandi, 98% in Malanville and 99% in Parakou. With deltamethrin 10x, mortality rates were 100% in Kandi, 96% in Malanville and 73% in Parakou. For the diagnostic dose of bendiocarb, suspected resistance was recorded in the communes of Malanville (97%) and Kandi (94%) while sensitivity was observed in Parakou (98%).Using the 10 × dose, mortality was 98% in Kandi, 100% in Malanville and 99% in Parakou. The frequencies of the kdr L1014F allele varied between 59 and 83% depending on the sites and species of the An. gambiae complex, while the frequency of the ace-1R G119S gene varied between 0 and 5%. Biochemical tests showed high levels of oxidase and esterase activity compared to the susceptible colony strain of An. gambiae sensu stricto (Kisumu strain). Conclusion Anopheles gambiae showed a generalized loss of susceptibility to permethrin and deltamethrin but also showed moderate to high intensity of resistance in different regions of Benin. This high intensity of resistance is a potential threat to the effectiveness of vector control.

scholarly journals Effect of aqueous extract of lemon (Citrus limon) on Anopheles gambiae sensu lato (Diptera: Culicidae) larvae tolerance in malaria vector control in Dogbo district in south-western Republic of Benin, West Africa

2021 ◽  
Vol 17 (2) ◽  
pp. 001-007
Author(s):  
Nazaire Aïzoun ◽  
Kourouma Koura ◽  
Arlette Adjatin
Keyword(s):  
West Africa ◽  
Anopheles Gambiae ◽  
Aqueous Extract ◽  
Larval Mortality ◽  
Citrus Limon ◽  
Mosquito Larvae ◽  
Distilled Water ◽  
Anopheles Gambiae S.L ◽  
Republic Of Benin ◽  
Water Saturated

The use of chemical insecticides causes important damages to environment and human health and there is a need to search for alternative solutions. This study aims to investigate on the effect of aqueous extract of lemon in Anopheles gambiae s.l. larvae tolerance in couffo department in south-western Republic of Benin, West Africa. Larvae of Anopheles gambiae s.l mosquitoes were collected from breeding sites using the dipping method in July 2020 during the rainy season in Dogbo district. A batch of 15 larvae of fourth instar were exposed to a mixture of aqueous extract of lemon with distilled water saturated with oxygen containing in each of five glass jars or test cups of same dimensions contained each 48 ml distilled water saturated with oxygen plus 2 ml of aqueous extract of lemon (Citrus limon) and one control jar containing no trace of aqueous extract of lemon. Larval mortality was recorded after 24hours, 48hours and 72hours exposure. The results show that the use of aqueous extract of lemon causes full-grown Anopheles larvae to die by suffocation. After the application of this mixture, the larvae of four instars cannot breathe. The use of aqueous extract of lemon is effective method for disturbing the siphonal respiration of mosquito larvae. Aqueous extract of lemon is effective method for mosquito larvae control.

scholarly journals To what extent does salt (NaCl) affect Anopheles gambiae sensu lato mosquito larvae survival?

2017 ◽  
Vol 49 (2) ◽  
Author(s):  
N. Lukwa ◽  
T. Mduluza ◽  
C. Nyoni ◽  
M. Zimba
Keyword(s):  
Disease Control ◽  
Anopheles Gambiae ◽  
Larval Mortality ◽  
Water Salinity ◽  
Lethal Concentration ◽  
Mosquito Larvae ◽  
Laboratory Conditions ◽  
Nacl Concentration

The effect of salt (NaCl) on <em>Anopheles gambiae sensu lato</em> (s.l.) mosquito larval breeding was ascertained under laboratory conditions. No larval mortality occurred when the Cl– concentrations were between 0.017 ppt (0.03 ppt salinity) and 7.371 ppt (13.25 ppt salinity). However, 9%, 24%, 73.5%, 91.5% and 99.5% larval mortality occurred at 10.828 ppt (19.49 ppt salinity), 16.069 ppt (28.95 ppt salinity), 18.739 ppt (33.77 ppt salinity), 32.587 ppt (58.82 ppt salinity) and 47.326 ppt (85.37 ppt salinity) NaCl concentrations respectively. The lower NaCl concentrations resulting in LC50, (lethal concentration for 50% larval mortality), LC90 (lethal concentration for 90% larval mortality), LC95 (lethal concentration for 95% larval mortality), and LC99 (lethal concentration for 99% larval mortality) were 23.12 ppt (41.19 ppt salinity), 24.91 ppt (44.42 ppt salinity), 27.76 ppt (49.56 ppt salinity) and 33.87 ppt (60.568 ppt salinity) respectively. The upper NaCl concentration resulting in LC50, LC90, LC95 and LC99 were 32.89 ppt (58.83 ppt salinity), 37.21 ppt (66.63 ppt salinity), 44.79 ppt (80.32 ppt salinity) and 63.76 ppt (114.55 ppt salinity) respectively. In conclusion, the level of water salinity may indicate the presence or absence of<em> An. gambiae</em> s.l. mosquito larvae and this information can be used for disease control purposes.

scholarly journals Effect of coconut oil on Anopheles gambiae sensu lato (Diptera: Culicidae) larvae tolerance in malaria vector control in Dogbo district in south-western Benin, West Africa

2021 ◽  
Vol 9 (2) ◽  
pp. 001-007
Author(s):  
Nazaire Aïzoun ◽  
Arlette Adjatin ◽  
Géorcelin Alowanou
Keyword(s):  
West Africa ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Larval Mortality ◽  
Coconut Oil ◽  
Malaria Vector Control ◽  
Mosquito Larvae ◽  
Distilled Water ◽  
Water Saturated

The use of chemical insecticides causes important damages to environment and human health and there is a need to search for alternative solutions. This study aims to investigate on the effect of coconut oil on Anopheles gambiae sensu lato larvae tolerance in malaria vector control in Dogbo district in south-western Benin, West Africa. Larvae of Anopheles gambiae s.l. mosquitoes were collected from breeding sites using the dipping method in May 2020 during the rainy season in Dogbo district. A batch of 25 larvae of fourth instar were exposed to a mixture of coconut oil with distilled water saturated with oxygen containing in each of five glass jars or test cups of same dimensions contained each 48 ml distilled water saturated with oxygen plus 2 ml of coconut oil and one control jar containing no trace of coconut oil. Larval mortality was recorded after 24 hours, 48 hours and 72hours exposure. The results show that the use of coconut oil causes full-grown Anopheles larvae to die by suffocation. After the application of this mixture, the larvae of four instars cannot breathe. The use of coconut oil is effective method for disturbing the siphonal respiration of mosquito larvae. Coconut oil is effective method for mosquito larvae control.

scholarly journals A pyrethroïd-treated bed net increases host attractiveness for Anopheles gambiae s.s. carrying the kdr allele in a dual-choice olfactometer

2016 ◽  
Author(s):  
Angélique Porciani ◽  
Malal Diop ◽  
Nicolas Moiroux ◽  
Tatiana Kadoke-Lambi ◽  
Anna Cohuet ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Anopheles Gambiae S.S ◽  
Host Seeking ◽  
Seeking Behavior ◽  
Sub Saharan ◽  
The Impact

AbstractThe use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely resistant to pyrethroïds, the insecticide family used on LLINs, which also threatens LLIN efficiency. There is therefore a crucial need for deciphering how insecticide-impregnated materials might affect the host-seeking behavior of malaria vectors in regards to insecticide resistance. In this study, we explored the impact of permethrin-impregnated net on the host attractiveness for Anopheles gambiae mosquitoes, either susceptible to insecticides, or carrying the insecticide resistance conferring allele kdr. Groups of female mosquitoes were released in a dual-choice olfactometer and their movements towards an attractive odor source (a rabbit) protected by insecticide-treated (ITN) or untreated nets (UTN) were monitored. Kdr homozygous mosquitoes, resistant to insecticides, were more attracted by a host behind an ITN than an UTN, while the presence of insecticide on the net did not affect the choice of susceptible mosquitoes. These results suggest that permethrin-impregnated net is detectable by malaria vectors and that the kdr mutation impacts their response to a LLIN protected host. We discuss the implication of these results for malaria vector control.

scholarly journals Potential metabolic resistance mechanisms to ivermectin in Anopheles gambiae: a synergist bioassay study

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Patricia Nicolas ◽  
Caroline Kiuru ◽  
Martin G. Wagah ◽  
Martha Muturi ◽  
Urs Duthaler ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Anopheles Gambiae ◽  
Control Strategies ◽  
Resistance Mechanisms ◽  
World Health ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Cytochrome P450 Enzymes ◽  
Metabolic Resistance ◽  
Active Efflux

Abstract Background Despite remarkable success obtained with current malaria vector control strategies in the last 15 years, additional innovative measures will be needed to achieve the ambitious goals for malaria control set for 2030 by the World Health Organization (WHO). New tools will need to address insecticide resistance and residual transmission as key challenges. Endectocides such as ivermectin are drugs that kill mosquitoes which feed on treated subjects. Mass administration of ivermectin can effectively target outdoor and early biting vectors, complementing the still effective conventional tools. Although this approach has garnered attention, development of ivermectin resistance is a potential pitfall. Herein, we evaluate the potential role of xenobiotic pumps and cytochrome P450 enzymes in protecting mosquitoes against ivermectin by active efflux and metabolic detoxification, respectively. Methods We determined the lethal concentration 50 for ivermectin in colonized Anopheles gambiae; then we used chemical inhibitors and inducers of xenobiotic pumps and cytochrome P450 enzymes in combination with ivermectin to probe the mechanism of ivermectin detoxification. Results Dual inhibition of xenobiotic pumps and cytochromes was found to have a synergistic effect with ivermectin, greatly increasing mosquito mortality. Inhibition of xenobiotic pumps alone had no effect on ivermectin-induced mortality. Induction of xenobiotic pumps and cytochromes may confer partial protection from ivermectin. Conclusion There is a clear pathway for development of ivermectin resistance in malaria vectors. Detoxification mechanisms mediated by cytochrome P450 enzymes are more important than xenobiotic pumps in protecting mosquitoes against ivermectin.

scholarly journals Evaluation of indigenous the nucleopolyhedrovirus (NPV) of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) in combination with chlorantraniliprole against Spodoptera species

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Ghulam Sarwar ◽  
Naeem Arshad Maan ◽  
Muhammad Ahsin Ayub ◽  
Muhammad Rafiq Shahid ◽  
Mubasher Ahmad Malik ◽  
...  
Keyword(s):  
Larval Mortality ◽  
Adult Emergence ◽  
Lethal Concentration ◽  
Pest Species ◽  
Vegetable Crops ◽  
Chemical Insecticide ◽  
Larval Instars ◽  
Novel Method ◽  
High Larval Mortality ◽  
Lepidoptera Noctuidae

Abstract Background The armyworms, Spodoptera exigua (Hübner), and S. litura (Fabricius) (Lepidoptera: Noctuidae) are polyphagous pests of many cash crops. Heavy crop losses have been reported for the fruit and vegetable crops each year owing to the diverse impact on global economies. The present study was aimed to sort out a novel method of pest control using the insect’s own nucleopolyhedrosis virus (NPV) alone and in combination with a new chemistry insecticide chlorantraniliprole. Results In the study, the effect of indigenous isolated nucleopolyhedrovirus (NPV) and the chemical insecticide (chlorantraniliprole) formulations against the 2nd and 4th larval instars of S. litura and S. exigua, collected from the different geographical region of Punjab (Pakistan) province, was evaluated. Three concentrations of the NPV isolate, sub-lethal (1 × 104, 6 × 104 POB ml−1), lethal (3 × 105 POB ml−1), and chlorantraniliprole 0.01 μl l−1, were applied alone and in combination against the 2nd and 4th larval instars of both pest species. The lethal concentration of NPV + chlorantraniliprole exhibited synergistic interaction and caused high larval mortality against both instars, while in all other combinations, additive effect was observed. Moreover, NPV + chlorantraniliprole at lethal concentration exhibited decreased pupation, adult emergence, and egg eclosion. Conclusion The implications of using NPV alone and in combination with an insecticide are discussed briefly in this study.

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 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

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Salum A. Mapua ◽  
Marceline F. Finda ◽  
Ismail H. Nambunga ◽  
Betwel J. Msugupakulya ◽  
Kusirye Ukio ◽  
...  
Keyword(s):  
Malaria Control ◽  
Public Engagement ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Production Plant ◽  
Community Members ◽  
Key Informants ◽  
Larval Source Management ◽  
Source Management

Abstract Background Larval source management was historically one of the most effective malaria control methods but is now widely deprioritized in Africa, where insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are preferred. However, in Tanzania, following initial successes in urban Dar-es-Salaam starting early-2000s, the government now encourages larviciding in both rural and urban councils nationwide to complement other efforts; and a biolarvicide production-plant has been established outside the commercial capital. This study investigated key obstacles and opportunities relevant to effective rollout of larviciding for malaria control, with a focus on the meso-endemic region of Morogoro, southern Tanzania. Methods Key-informants were interviewed to assess awareness and perceptions regarding larviciding among designated health officials (malaria focal persons, vector surveillance officers and ward health officers) in nine administrative councils (n = 27). Interviewer-administered questionnaires were used to assess awareness and perceptions of community members in selected areas regarding larviciding (n = 490). Thematic content analysis was done and descriptive statistics used to summarize the findings. Results A majority of malaria control officials had participated in larviciding at least once over the previous three years. A majority of community members had neutral perceptions towards positive aspects of larviciding, but overall support for larviciding was high, although several challenges were expressed, notably: (i) insufficient knowledge for identifying relevant aquatic habitats of malaria vectors and applying larvicides, (ii) inadequate monitoring of programme effectiveness, (iii) limited financing, and (iv) lack of personal protective equipment. Although the key-informants reported sensitizing local communities, most community members were still unaware of larviciding and its potential. Conclusions The larviciding programme was widely supported by both communities and malaria control officials, but there were gaps in technical knowledge, implementation and public engagement. To improve overall impact, it is important to: (i) intensify training efforts, particularly for identifying habitats of important vectors, (ii) adopt standard technical principles for applying larvicides or larval source management, (iii) improve financing for local implementation and (iv) improve public engagement to boost community awareness and participation. These lessons could also be valuable for other malaria endemic areas wishing to deploy larviciding for malaria control or elimination.

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