The Larvicidal Efficacy ofBacillus thuringiensissubsp.IsraelensisAgainst Five AfricanAnopheles(Diptera: Culicidae) Species

Ketseoglou, Irene; Koekemoer, Lizette L.; Coetzee, Maureen; Bouwer, Gustav

doi:10.4001/003.019.0110

Cited by 6 publications

(7 citation statements)

References 33 publications

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“…arabiensis (3rd)480.0076 b –NICD, Johannesburg (South Africa) Bti (not stated)Not stated An. quadriannulatus (3rd)242.975.02[64]– An. arabiensis (3rd)243.7210.10 a – An.…”

Section: Resultsmentioning

confidence: 99%

“…funestus (3rd)244.4413.50 a a LC 90/95 : a dose marked with a represents LC 90 ; unmarked doses represent LC 95 b Doses provided in µg/l were converted to mg/l for a uniform presentation. Concentrations reported in mg/l except for study [64] are given in 10 4 spores/ml Abbreviations : Bti , Bacillus thuringiensis var. israelensis ; Bs , Bacillus sphaericus ; ITU, international toxic units; WDG, water-dispersible granules; PP, primary powder; TP, technical powder; FC, flowable concentrate; SD, spray dried; ICIPE, International Centre of Insect Physiology and Ecology; MRC, Medical Research Council; KCCR, Kumasi Centre for Collaborative Research; UFS, Ubwari Field Station; NOCMVD, National Organization for the Control of Malaria and other Vector-borne Diseases; NICD, National Institute of Communicable Diseases; LC, lethal concentration (concentration that kills 50/95% of the test subjects)…”

Section: Resultsmentioning

confidence: 99%

“…b Doses provided in µg/l were converted to mg/l for a uniform presentation. Concentrations reported in mg/l except for study [64] are given in 10 4 spores/ml…”

Section: Resultsmentioning

confidence: 99%

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Bacterial larvicides used for malaria vector control in sub-Saharan Africa: review of their effectiveness and operational feasibility

et al. 2019

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Several trials and reviews have outlined the potential role of larviciding for malaria control in sub-Saharan Africa (SSA) to supplement the core indoor insecticide-based interventions. It has been argued that widespread use of long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) interventions in many parts of Africa result in many new areas with low and focal malaria transmission that can be targeted with larvicides. As some countries in SSA are making good progress in malaria control, larval source management, particularly with bacterial larvicides, could be included in the list of viable options to maintain the gains achieved while paving the way to malaria elimination. We conducted a review of published literature that investigated the application of bacterial larvicides, Bacillus thuringiensis var. israelensis ( Bti ) and/or Bacillus sphaericus ( Bs ) for malaria vector control in SSA. Data for the review were identified through PubMed, the extensive files of the authors and reference lists of relevant articles retrieved. A total of 56 relevant studies were identified and included in the review. The findings indicated that, at low application rates, bacterial larvicide products based on Bti and/or Bs were effective in controlling malaria vectors. The larvicide interventions were found to be feasible, accepted by the general community, safe to the non-target organisms and the costs compared fairly well with those of other vector control measures practiced in SSA. Our review suggests that larviciding should gain more ground as a tool for integrated malaria vector control due to the decline in malaria which creates more appropriate conditions for the intervention and to the recognition of limitations of insecticide-based vector control tools. The advancement of new technology for mapping landscapes and environments could moreover facilitate identification and targeting of the numerous larval habitats preferred by the African malaria vectors. To build sustainable anti-larval measures in SSA, there is a great need to build capacity in relevant specialties and develop organizational structures for governance and management of larval source management programmes.

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“…arabiensis (3rd)480.0076 b –NICD, Johannesburg (South Africa) Bti (not stated)Not stated An. quadriannulatus (3rd)242.975.02[64]– An. arabiensis (3rd)243.7210.10 a – An.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Bacterial larvicides used for malaria vector control in sub-Saharan Africa: review of their effectiveness and operational feasibility

et al. 2019

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“…Bacillus thuringiensis var israelensis ( Bti ) and Bacillus sphaericus ( Bs ) are the two potential biological insecticides that have been used for mosquito control since their discoveries during the mid-1970s. They are highly selective and are therefore environmentally safe to non-target organisms [8]. Moreover, to become resistant to Bti , an individual must develop resistance mechanisms to each of the four toxins, namely Cry4Aa, Cry4Ba, Cry11Aa, and Cyt1A [9].…”

Section: Introductionmentioning

confidence: 99%

Impact of sunlight exposure on the residual efficacy of biolarvicides Bacillus thuringiensis israelensis and Bacillus sphaericus against the main malaria vector, Anopheles gambiae

Zogo

Tchiekoi

Koffi

et al. 2019

Malar J

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Background Biotic and abiotic factors have been reported to affect the larvicidal efficacy of Bacillus thuringiensis israelensis ( Bti ) and Bacillus sphaericus ( Bs ), although the extent to which they are affected has been poorly documented. This paper studies the effect of sunlight exposure on the efficacy of a new larvicide formulation based on both Bti and Bs , herein after referred to as BTBSWAX, applied against two different larval stages. Methods The emergence of inhibition exhibited by BTBSWAX at three different dosages (1 g/m 2 , 1.5 g/m 2 , and 2 g/m 2 ) was monitored under semi-field conditions using a total of 32 containers comprising 16 that were covered and 16 that were uncovered. Two experiments were conducted using first- and second-instar larvae of Anopheles gambiae , respectively. Results BTBSWAX at 2 g/m 2 in covered containers exhibited high emergence inhibition (> 80%) when larvae were exposed from 1st instar on day-6 post-treatment, whereas the emergence inhibition was only 28% in uncovered containers. For larvae exposed from 1st instar on day-12 post-treatment, the emergence inhibition was moderate (70%) in covered containers but was low (< 20%) in uncovered containers. For larvae exposed from 2nd instar on day-10 post-treatment, the emergence inhibition was moderate (31%) in covered containers but was very low (< 10%) in uncovered containers. Moreover, the residual efficacy of BTBSWAX was markedly affected by environmental stresses, including sunlight exposure (Hazard ratio (HR) = 0.12, p < 0.001 and HR = 0.63, p = 0.033 for BTBSWAX at 2 g/m 2 against 1st and 2nd instar larvae, respectively). Conclusion These findings emphasize the impact of environmental variables (e.g., sunlight exposure) on the residual efficacy of Bti and Bs biolarvicides in the field. They hence highlight the need to take these factors into account for larvicide formulation development processes. Moreover, studies of the ecology of Anopheles larvae in targeted areas are also crucial for the integration of larval control strategies into malaria transmission plans devised by national malaria control programmes of endemic countries. Electronic supplementary material The online version of this article (10.1186/s12936-019-2687-0) contains supplementary material, which is available to authorized users.

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“…and An. arabiensis at LC 50 , but the former was found to be significantly more susceptible at LC 90 (Ketseoglou et al ., ). However, comparisons of susceptibility between An.…”

Section: Discussionmentioning

confidence: 97%

Susceptibility of Anopheles gambiae complex mosquitoes to microbial larvicides in diverse ecological settings in western Kenya

Derua

Kahindi

Mosha

et al. 2019

Medical Vet Entomology

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The microbial larvicides Bacillus thuringiensis var. israelensis (Bti) and Bacillus sphaericus (Bs) (Bacillales: Bacillaceae) are well known for their efficacy and safety in mosquito control. In order to assess their potential value in future mosquito control strategies in western Kenya, the current study tested the susceptibility of five populations of Anopheles gambiae complex mosquitoes (Diptera: Culicidae), collected from five diverse ecological sites in this area, to Bti and Bs under laboratory conditions. In each population, bioassays were conducted with eight concentrations of larvicide (Bti/Bs) in four replicates and were repeated on three separate days. Larval mortality was recorded at 24 h or 48 h after the application of larvicide and subjected to probit analysis. A total of 2400 An. gambiae complex larvae from each population were tested for their susceptibility to Bti and Bs. The mean (± standard error of the mean, SEM) lethal concentration values of Bti required to achieve 50% and 95% larval mortality (LC 50 and LC 95 ) across the five populations were 0.062 (± 0.005) mg/L and 0.797 (± 0.087) mg/L, respectively. Corresponding mean (± SEM) values for Bs were 0.058 (± 0.005) mg/L and 0.451 (± 0.053) mg/L, respectively. Statistical analysis indicated that the five populations of An. gambiae complex mosquitoes tested were fully susceptible to Bti and Bs, and there was no significant variation in susceptibility among the tested populations.

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The Larvicidal Efficacy ofBacillus thuringiensissubsp.IsraelensisAgainst Five AfricanAnopheles(Diptera: Culicidae) Species

Cited by 6 publications

References 33 publications

Bacterial larvicides used for malaria vector control in sub-Saharan Africa: review of their effectiveness and operational feasibility

Bacterial larvicides used for malaria vector control in sub-Saharan Africa: review of their effectiveness and operational feasibility

Impact of sunlight exposure on the residual efficacy of biolarvicides Bacillus thuringiensis israelensis and Bacillus sphaericus against the main malaria vector, Anopheles gambiae

Susceptibility of Anopheles gambiae complex mosquitoes to microbial larvicides in diverse ecological settings in western Kenya

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