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Methanolic extract of Agerantum conyzoides exhibited toxicity and growth disruption activities against Anopheles gambiae sensu stricto and Anopheles arabiensis larvae

View Article: PubMed Central - PubMed

ABSTRACT

Background: Vector control remains the mainstay to effective malaria management. The negative implications following persistent application of synthetic insecticides geared towards regulation of mosquito populations have necessitated prospection for ecofriendly effective chemistries. Plant-derived compounds have the potential to control malaria-transmitting mosquito populations. Previously, Agerantum conyzoides extracts have demonstrated toxicity effects on disease-transmitting mosquitoes. However, their efficacy in controlling Afrotropical malaria vectors remains unclear. Herein, the toxicity and growth disruption activities of crude methanolic leaf extract of A. conyzoides on Anopheles gambiae sensu stricto and An. arabiensis larvae were assessed.

Methods: Late third (L3) instars of An. gambiae s.s and An. arabiensis larvae were challenged with increasing doses of crude methanolic extract of A. conyzoides. The larval mortality rates were recorded every 24 h and the LC50 values determined at their associated 95% confidence levels. ANOVA followed by Post-hoc Student-Newman-Keuls (SNK) test was used to compare results between treatment and control groups. Phytochemical profiling of the extract was performed using standard chemical procedures.

Results: Treatment of larvae with the methanolic extract depicted dose-dependent effects with highest mortality percentages of ≥ 69% observed when exposed with 250 ppm and 500 ppm for 48 h while growth disruption effects were induced by sublethal doses of between 50–100 ppm for both species. Relative to experimental controls, the extract significantly reduced larval survival in both mosquito species (ANOVA, F(8,126) = 43.16776, P < 0.001). The LC50 values of the extract against An. gambiae s.s ranged between 84.71–232.70 ppm (95% CI 81.17–239.20), while against An. arabiensis the values ranged between 133.46–406.35 ppm (95% CI 131.51–411.25). The development of the juvenile stages was arrested at pupal-larval intermediates and adult emergence. The presence of alkaloids, aglycone flavonoids, triterpenoids, tannins and coumarins can partly be associated with the observed effects.

Conclusion: The extract displayed considerable larvicidal activity and inhibited emergence of adult mosquitoes relative to experimental controls, a phenomenon probably associated with induced developmental hormone imbalance. Optimization of the bioactive compounds could open pathways into vector control programmes for improved mosquito control and reduced malaria transmission rates.

No MeSH data available.


Related in: MedlinePlus

Dose-response curves for An. gambiae s.s and An. arabiensis larvae to A. conyzoides extract for 24 h, 48 h and 72 h post exposure. Doses are log-transformed and each point on the plots represents percentage mean (± S.D) larval mortality of 5 replicates for each dose of the extract
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Fig1: Dose-response curves for An. gambiae s.s and An. arabiensis larvae to A. conyzoides extract for 24 h, 48 h and 72 h post exposure. Doses are log-transformed and each point on the plots represents percentage mean (± S.D) larval mortality of 5 replicates for each dose of the extract

Mentions: The toxicity of crude methanolic extract of A. conyzoides against late 3rd instars of An. gambiae s.s and An. arabiensis was evaluated. The toxicity of the extract was demonstrated to be dose-dependent with high doses of 250 ppm and 500 ppm showing ≥ 69% larval mortality at 48 h post-exposure compared to the lower doses of 50 ppm and 100 ppm which gave < 50% larval mortality (Table 2). Maximum larval mortality (100%) was recorded at 500 ppm on exposure to An. gambiae s.s larvae for 48 h with only 88% attained against An. arabiensis. A 100% larval survival was noted in the negative control group for the entire analysis period. Relative to controls, the extract significantly reduced survival rates of An. gambiae s.s (ANOVA, F(4,70) = 115.5534, P < 0.001) and An. arabiensis larvae (ANOVA, F(4,70) = 31.7382, P < 0.001). There was significant susceptibility difference between the two mosquito species to the extract (ANOVA, F(8,111) = 25.6398, P < 0.001). A time- and dose-dependent reduction in survival rates of extract-challenged mosquito larvae was demonstrated in Fig. 1.Table 2


Methanolic extract of Agerantum conyzoides exhibited toxicity and growth disruption activities against Anopheles gambiae sensu stricto and Anopheles arabiensis larvae
Dose-response curves for An. gambiae s.s and An. arabiensis larvae to A. conyzoides extract for 24 h, 48 h and 72 h post exposure. Doses are log-transformed and each point on the plots represents percentage mean (± S.D) larval mortality of 5 replicates for each dose of the extract
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5120420&req=5

Fig1: Dose-response curves for An. gambiae s.s and An. arabiensis larvae to A. conyzoides extract for 24 h, 48 h and 72 h post exposure. Doses are log-transformed and each point on the plots represents percentage mean (± S.D) larval mortality of 5 replicates for each dose of the extract
Mentions: The toxicity of crude methanolic extract of A. conyzoides against late 3rd instars of An. gambiae s.s and An. arabiensis was evaluated. The toxicity of the extract was demonstrated to be dose-dependent with high doses of 250 ppm and 500 ppm showing ≥ 69% larval mortality at 48 h post-exposure compared to the lower doses of 50 ppm and 100 ppm which gave < 50% larval mortality (Table 2). Maximum larval mortality (100%) was recorded at 500 ppm on exposure to An. gambiae s.s larvae for 48 h with only 88% attained against An. arabiensis. A 100% larval survival was noted in the negative control group for the entire analysis period. Relative to controls, the extract significantly reduced survival rates of An. gambiae s.s (ANOVA, F(4,70) = 115.5534, P < 0.001) and An. arabiensis larvae (ANOVA, F(4,70) = 31.7382, P < 0.001). There was significant susceptibility difference between the two mosquito species to the extract (ANOVA, F(8,111) = 25.6398, P < 0.001). A time- and dose-dependent reduction in survival rates of extract-challenged mosquito larvae was demonstrated in Fig. 1.Table 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Vector control remains the mainstay to effective malaria management. The negative implications following persistent application of synthetic insecticides geared towards regulation of mosquito populations have necessitated prospection for ecofriendly effective chemistries. Plant-derived compounds have the potential to control malaria-transmitting mosquito populations. Previously, Agerantum conyzoides extracts have demonstrated toxicity effects on disease-transmitting mosquitoes. However, their efficacy in controlling Afrotropical malaria vectors remains unclear. Herein, the toxicity and growth disruption activities of crude methanolic leaf extract of A. conyzoides on Anopheles gambiae sensu stricto and An. arabiensis larvae were assessed.

Methods: Late third (L3) instars of An. gambiae s.s and An. arabiensis larvae were challenged with increasing doses of crude methanolic extract of A. conyzoides. The larval mortality rates were recorded every 24&nbsp;h and the LC50 values determined at their associated 95% confidence levels. ANOVA followed by Post-hoc Student-Newman-Keuls (SNK) test was used to compare results between treatment and control groups. Phytochemical profiling of the extract was performed using standard chemical procedures.

Results: Treatment of larvae with the methanolic extract depicted dose-dependent effects with highest mortality percentages of&thinsp;&ge;&thinsp;69% observed when exposed with 250&nbsp;ppm and 500&nbsp;ppm for 48&nbsp;h while growth disruption effects were induced by sublethal doses of between 50&ndash;100&nbsp;ppm for both species. Relative to experimental controls, the extract significantly reduced larval survival in both mosquito species (ANOVA, F(8,126)&thinsp;=&thinsp;43.16776, P&thinsp;&lt;&thinsp;0.001). The LC50 values of the extract against An. gambiae s.s ranged between 84.71&ndash;232.70&nbsp;ppm (95% CI 81.17&ndash;239.20), while against An. arabiensis the values ranged between 133.46&ndash;406.35&nbsp;ppm (95% CI 131.51&ndash;411.25). The development of the juvenile stages was arrested at pupal-larval intermediates and adult emergence. The presence of alkaloids, aglycone flavonoids, triterpenoids, tannins and coumarins can partly be associated with the observed effects.

Conclusion: The extract displayed considerable larvicidal activity and inhibited emergence of adult mosquitoes relative to experimental controls, a phenomenon probably associated with induced developmental hormone imbalance. Optimization of the bioactive compounds could open pathways into vector control programmes for improved mosquito control and reduced malaria transmission rates.

No MeSH data available.


Related in: MedlinePlus