Mosquitocidal bacterial toxins: diversity, mode of action and resistance phenomena

Charles, Jean‐François; Nielsen-LeRoux, Christina

doi:10.1590/s0074-02762000000700034

Cited by 60 publications

(49 citation statements)

References 30 publications

(17 reference statements)

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“…The sequence of 12 bases coding for a trypsin cleavage site (IEGR) was introduced upstream (bases [13][14][15][16][17][18][19][20][21][22][23][24], to release in the larval midgut free TMOF that inhibits trypsin biosynthesis:…”

Section: Cloning and Expression Of Tmfa In Anabaenamentioning

confidence: 99%

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Synergy Between Aedes aegypti Trypsin Modulating Oostatic Factor and δ-Endotoxins

Borovsky¹,

Khasdan²,

Nauwelaers³

et al. 2013

TOTNJ

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Starved first instar Aedes aegypti larvae were 35-fold more sensitive to Bacillus thuringiensis subsp. israelensis (Bti) toxins than fed larvae. Feeding larvae Pichia pastoris yeast cells expressing tmfA (synthetic gene coding for the Trypsin Modulating Oostatic Factor of Ae. aegypti) together with Escherichia coli cells expressing Bti toxin genes (cry4Aa, cry11Aa, cyt1Aa and p20) indicate that TMOF and Cry toxins are synergisitic. tmfA was cloned and expressed in the cyanobacterium Anabaena PCC 7120 and the hormone was purified by HPLC and identified by ELISA. The amount of TMOF synthesized by Anabaena was low (0.5 -1 μg in 10 8 cells). P. pastoris, which synthesizes high amounts of heterologous proteins in the presence of methanol and is readily consumed by mosquito larvae, was genetically engineered to produce more TMOF. Codon-optimized synthetic genes, cry11Aa-tmfA and gst-cry11Aa-tmfA, that were cloned into P. pastoris and fed to Ae. aegypti larvae caused 87.5% mortality in 5 days. GST (glutathione-S-transferase) enhanced the activity of Cry11A-TMOF and protected it from heat denaturation. Cell free extracts of recombinant P. pastoris cells killed 40% of tested 4 th instar larvae within 24 h, and mass spectra analysis confirmed that the recombinants synthesize Cry11Aa. This report shows for the first time that Cry toxins and TMOF are synergists to Ae. aegypti larvae when jointly fed or expressed in recombinant P. pastoris.

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Section: Cloning and Expression Of Tmfa In Anabaenamentioning

confidence: 99%

“…Its Cry toxins are per os poisons; they bind to larval midgut causing rapid death, and hence are considered safe larvicides that do not damage the environment [12]. Low probability of developing resistance has been observed in field populations of mosquitoes despite 25 years of extensive field usage [13,14].…”

Section: Introductionmentioning

confidence: 99%

Synergy Between Aedes aegypti Trypsin Modulating Oostatic Factor and δ-Endotoxins

Borovsky¹,

Khasdan²,

Nauwelaers³

et al. 2013

TOTNJ

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“…Though effective this strategy is accompanied with serious harm to human and other animals in the environment (Cartilla and De la Cruz, 2012). In addition continued use of synthetic insecticides has been demonstrated to lead to reduced control due to development of resistant in insect populations (Charles and Nielsen-LeRoux, 2000).…”

Section: Introductionmentioning

confidence: 99%

Effective Dose of Crude Ethanol and Aqueous Extracts of <i>Phytolacca Dodecandra</i> (L’ Herit) on <i>Anopheles Gambiae</i> (Diptera: Culicidae) Larvae

Yugi¹,

Owour²,

Kogogo³

et al. 2015

jmr

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Objective: malaria vector control is either by adult or larvae management. This study reports on the effective dose of crude ethanol and aqueous extracts of leaf and mature green fruits of Endod; Phytolacca dodecandra (L' Herit) as a larvicide against Anopheles gambiae (Diptera: Culicidae) mosquitoes. rd and 4 th instars) of An. gambiae were transferred using droppers into plastic containers measuring 6 cm mouth and 5.7 cm base diameter by 3.5 cm height arranged in sets. Each container contained an approximate of 33 millilitre solution of a particular concentration of leaf (shoot or midsection) or fruit extracts of Endod. Endod plants were sourced from Nyando and Eldoret. The solutions were a serial dilution of 40, 20, 10, 5 and 5mg/100mls of the crude extracts. Solutions of Neem and deltamethrin were used as positive control and that of water only as negative control. Three replicates were set up for each concentration. WHO threshold of > 80 % mortality was used as standard to assess effectiveness of the larvicide.Results: Over 80% of all larvae (L1s, L2s, L3s and L4s) died from exposure to concentrations of 20mg and higher of ethanol extracts of mature green fruits of Endod irrespective of source. Only 40 mg/100 mls of aqueous extracts of Endod leaves of the shoot sourced from Eldoret killed > 80% of exposed L1s. Higher mortalities were observed for extracts from leaves of the shoot of Endod than those from the midsection.Conclusion: Higher doses of ethanol and water extracts of Endod leaves and fruits were lethal to all stages of An. gambiae larvae.

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“…israelensis formulations have been used for more than 4 decades, no substantial resistance has been observed in the field, although resistance to individual toxins has been observed in the laboratory (7). However, resistance to L. sphaericus toxins has been observed in the field in a number of countries (8)(9)(10). This ability of organisms to adapt and develop resistance to new insecticides indicates a need for the development or discovery of new biological insecticides.…”

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confidence: 99%

The Cry Toxin Operon of Clostridium bifermentans subsp. malaysia Is Highly Toxic to Aedes Larval Mosquitoes

Qureshi

Chawla

Likitvivatanavong

et al. 2014

Appl Environ Microbiol

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The management and control of mosquito vectors of human disease currently rely primarily on chemical insecticides. However, larvicidal treatments can be effective, and if based on biological insecticides, they can also ameliorate the risk posed to human health by chemical insecticides. The aerobic bacteria Bacillus thuringiensis and Lysinibacillus sphaericus have been used for vector control for a number of decades. But a more cost-effective use would be an anaerobic bacterium because of the ease with which these can be cultured. More recently, the anaerobic bacterium Clostridium bifermentans subsp. malaysia has been reported to have high mosquitocidal activity, and a number of proteins were identified as potentially mosquitocidal. However, the cloned proteins showed no mosquitocidal activity. We show here that four toxins encoded by the Cry operon, Cry16A, Cry17A, Cbm17.1, and Cbm17.2, are all required for toxicity, and these toxins collectively show remarkable selectivity for Aedes rather than Anopheles mosquitoes, even though C. bifermentans subsp. malaysia is more toxic to Anopheles. Hence, toxins that target Anopheles are different from those expressed by the Cry operon.

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Mosquitocidal bacterial toxins: diversity, mode of action and resistance phenomena

Cited by 60 publications

References 30 publications

Synergy Between Aedes aegypti Trypsin Modulating Oostatic Factor and δ-Endotoxins

Synergy Between Aedes aegypti Trypsin Modulating Oostatic Factor and δ-Endotoxins

Effective Dose of Crude Ethanol and Aqueous Extracts of <i>Phytolacca Dodecandra</i> (L’ Herit) on <i>Anopheles Gambiae</i> (Diptera: Culicidae) Larvae

The Cry Toxin Operon of Clostridium bifermentans subsp. malaysia Is Highly Toxic to Aedes Larval Mosquitoes

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