1
|
Mahyoub JA, Algamdi AG, Aljameeli MM. Resistance development to bioinsecticides in Aedes aegypti (Culicidae: Diptera), the vector of dengue fever in Saudi Arabia. Saudi J Biol Sci 2023; 30:103776. [PMID: 37635838 PMCID: PMC10458291 DOI: 10.1016/j.sjbs.2023.103776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 07/31/2023] [Accepted: 08/05/2023] [Indexed: 08/29/2023] Open
Abstract
A laboratory strain of Aedes aegypti (L) was subjected repeatedly to larval selection pressure with two bacterial insecticides, spinosad (Saccharopolyspora spinosa) and bacilod (Bacillus thuringiensis israelensis). The results indicated that the mosquito Ae. aegypti acquired low resistance to spinosad and bacilod by about 3.1 and 2.4-fold, respectively, due to selection pressure for fifteen successive generations. The slope values of the selected strains were increased gradually from one generation to the next, indicating moderate homogeneity between individuals in their response to the test bio-insecticide. Moreover, larval selection with current bacterial bioinsecticides prolonged the time required to digest a blood meal. It showed an evident decrease in the reproductive potential of adult mosquitoes surviving selected larvae.
Collapse
Affiliation(s)
- Jazem A. Mahyoub
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, P. O. Box: 80203, Jeddah, Saudi Arabia
| | - Abdullah G. Algamdi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, P. O. Box: 80203, Jeddah, Saudi Arabia
| | - Mohammad M. Aljameeli
- Department of Biology, College of Arts and Sciences, Northern Border University, Rafha, Saudi Arabia
| |
Collapse
|
2
|
Genetic diversity of Brazilian Bacillus thuringiensis isolates with toxicity against Aedes aegypti (Diptera: Culicidae). Sci Rep 2022; 12:14408. [PMID: 36002607 PMCID: PMC9402949 DOI: 10.1038/s41598-022-18559-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 08/16/2022] [Indexed: 11/08/2022] Open
Abstract
Bacillus thuringiensis (Bt) isolates native to Maranhão (BtMA) that are highly toxic to Aedes aegypti larvae and seven standard subspecies of Bt were analyzed for genetic diversity using the rep-PRC technique with BOX, ERIC, REP, MB1, and GTG5 markers. The rep-PCR technique is considered an extremely reliable, reproducible, fast and highly discriminatory technique that may be used even among populations of the same species. These five markers revealed a total of 38 polymorphic DNA fragments for 30 BtMA isolates. Eight groups were obtained with the dendrogram generated through Pearson's correlation analysis, with four groups formed only with BtMA isolates and four comprised of isolates of BtMA and the standard subspecies toxic to dipterans and lepidopterans. Despite the high genetic diversity of BtMA, a low correlation between the collection site, gene content and mortality against A. aegypti larvae was evidenced. The clustering of the standard subspecies of Bt that were toxic against dipterans with BtMA isolates confirm the mosquitocidal action of the native isolates from Maranhão, and they can be used as an alternative for A. aegypti control and other insects of medical importance and for the control of agricultural pests.
Collapse
|
3
|
Fayad N, Patiño-Navarrete R, Kambris Z, Antoun M, Osta M, Chopineau J, Mahillon J, El Chamy L, Sanchis V, Kallassy Awad M. Characterization and Whole Genome Sequencing of AR23, a Highly Toxic Bacillus thuringiensis Strain Isolated from Lebanese Soil. Curr Microbiol 2019; 76:1503-1511. [PMID: 31563972 DOI: 10.1007/s00284-019-01775-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 08/21/2019] [Accepted: 09/17/2019] [Indexed: 12/14/2022]
Abstract
The demand for sustainable and eco-friendly control methods of pests and insects is increasing worldwide. From this came the interest in Bacillus thuringiensis, an entomopathogenic bacterium capable of replacing chemical pesticides. However, the possibility of pests developing resistance to a particular strain may impair its use, and there is a need to identify novel strains of this species as potential commercial biopesticides. B. thuringiensis sv. israelensis is one of the most successful serovars, widely commercialized for its activity against black fly and mosquito larvae. In this study, we isolated, characterized, and sequenced a new Lebanese B. thuringiensis sv. israelensis isolate, strain AR23. Compared to the commercialized reference strain AM65-52 (Vectobac®, Sumitomo), AR23 showed an increased activity against several mosquito species. The genomic analysis revealed that this strain, compared to AM65-52, possesses a simplified plasmid content and an additional functional cry4Ba coding gene that most likely accounts for the increased effectiveness of this strain in mosquito larvae killing.
Collapse
Affiliation(s)
- Nancy Fayad
- Laboratory of Biodiversity and Functional Genomics, Faculty of Science, Université Saint-Joseph de Beyrouth, Beirut, Lebanon
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Rafael Patiño-Navarrete
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Zakaria Kambris
- Biology Department, Faculty of Arts and Sciences, American University of Beirut, Beirut, Lebanon
| | - Mandy Antoun
- Laboratory of Biodiversity and Functional Genomics, Faculty of Science, Université Saint-Joseph de Beyrouth, Beirut, Lebanon
- Institut Charles Gerhardt de Montpellier (ICGM), CNRS UMR 5253/UM/ENSCM Université de Montpellier Campus Triolet, Place Eugène Bataillon, 34095, Montpellier Cedex 5, France
- Université de Nîmes, Rue Georges Salan, 30000, Nîmes, France
| | - Mike Osta
- Biology Department, Faculty of Arts and Sciences, American University of Beirut, Beirut, Lebanon
| | - Joel Chopineau
- Institut Charles Gerhardt de Montpellier (ICGM), CNRS UMR 5253/UM/ENSCM Université de Montpellier Campus Triolet, Place Eugène Bataillon, 34095, Montpellier Cedex 5, France
- Université de Nîmes, Rue Georges Salan, 30000, Nîmes, France
| | - Jacques Mahillon
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Laure El Chamy
- Génétique de La Drosophile Et Virulence Microbienne (GDVM), Faculty of Science, Université Saint-Joseph de Beyrouth, Beirut, Lebanon
| | - Vincent Sanchis
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Mireille Kallassy Awad
- Laboratory of Biodiversity and Functional Genomics, Faculty of Science, Université Saint-Joseph de Beyrouth, Beirut, Lebanon.
| |
Collapse
|
4
|
Persistence of Toxic Activity of Fermentation Extracts from Bacillus thuringiensis var. israelensis after More Than Three Decades of Storage. Int J Microbiol 2018; 2017:5402748. [PMID: 29358951 PMCID: PMC5735669 DOI: 10.1155/2017/5402748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 10/11/2017] [Accepted: 10/31/2017] [Indexed: 11/17/2022] Open
Abstract
This study was carried out to determine the persistence of toxicity of fermentation extracts of Bacillus thuringiensis var. israelensis after more than three decades of storage. For this purpose, a population of Aedes aegypti was established. The mortality rate of 20 spore-crystal extracts purified using the acetone-lactose coprecipitation method was measured and evaluated by bioassays according to a modified WHO protocol. The extracts with the highest mortality rate were determined in triplicate by their LD50 and LD98. All extracts showed toxicity at the highest tested dose (1000 ppm) and some, such as strains 3260 and 3501, still killed larvae at doses as low as 0.01 ppm. These data are surprising because no study on the activity of B. thuringiensis toxic proteins after such a long storage time has been reported.
Collapse
|
5
|
Park HW, Hice RH, Federici BA. Effect of Promoters and Plasmid Copy Number on Cyt1A Synthesis and Crystal Assembly in Bacillus thuringiensis. Curr Microbiol 2015; 72:33-40. [DOI: 10.1007/s00284-015-0911-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 08/06/2015] [Indexed: 10/23/2022]
|
6
|
Wirth MC, Walton WE, Federici BA. Evolution of Resistance in Culex quinquefasciatus (Say) Selected With a Recombinant Bacillus thuringiensis Strain-Producing Cyt1Aa and Cry11Ba, and the Binary Toxin, Bin, From Lysinibacillus sphaericus. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:1028-1035. [PMID: 26336254 PMCID: PMC4668759 DOI: 10.1093/jme/tjv115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/17/2015] [Indexed: 06/05/2023]
Abstract
Fourth instars of Culex quinquefasciatus (Say) (Diptera: Culicidae) were selected with a recombinant bacterial strain synthesizing the mosquitocidal proteins from Lysinibacillus sphaericus (Bin) and Cry11Ba and Cyt1Aa from Bacillus thuringiensis. Selection was initiated in Generation 1 with a concentration of 0.04 μg/ml, which rose to a maximum selection concentration of 8.0 μg/ml in Generation 14, followed by an unexpected, rapid increase in mortality in Generation 15. Subsequently, a selection concentration of 0.8 μg/ml was determined to be survivable. During this same period, resistance rose to nearly 1,000-fold (by Generation 12) and declined to 18.8-fold in Generation 19. Resistance remained low and fluctuated between 5.3 and 7.3 up to Generation 66. The cross-resistance patterns and interactions among the component proteins were analyzed to identify possible causes of this unusual pattern of evolution. Poor activity in the mid-range concentrations and lower-than-expected synergistic interactions were identified as potential sources of the early resistance. These findings should be considered in the development of genetically engineered strains intended to control nuisance and vector mosquitoes.
Collapse
Affiliation(s)
- Margaret C Wirth
- Department of Entomology, University of California, Riverside, CA 92521.
| | - William E Walton
- Department of Entomology, University of California, Riverside, CA 92521
| | - Brian A Federici
- Department of Entomology, University of California, Riverside, CA 92521. Interdepartmental Graduate Programs in Microbiology, and Cell, Molecular and Developmental Biology, University of California, Riverside, CA 92521
| |
Collapse
|
7
|
Lee SB, Aimanova KG, Gill SS. Alkaline phosphatases and aminopeptidases are altered in a Cry11Aa resistant strain of Aedes aegypti. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 54:112-121. [PMID: 25242559 PMCID: PMC4254116 DOI: 10.1016/j.ibmb.2014.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/10/2014] [Accepted: 09/13/2014] [Indexed: 06/01/2023]
Abstract
Bacillus thuringiensis subsp. israelensis (Bti) is widely used for the biological control of mosquito populations. However, the mechanism of Bti toxins is still not fully understood. To further elucidate the mechanism of Bti toxins, we developed an Aedes aegypti resistant strain that shows high-level resistance to Cry11Aa toxin. After 27 selections with Cry11Aa toxin, the larvae showed a 124-fold resistance ratio for Cry11Aa (strain G30). G30 larvae showed cross-resistance to Cry4Aa (66-fold resistance), less to Cry4Ba (13-fold), but not to Cry11Ba (2-fold). Midguts from these resistant larvae did not show detectable difference in the processing of the Cry11Aa toxin compared to that in susceptible larvae (WT). Brush border membrane vesicles (BBMV) from resistant larvae bound slightly less Cry11Aa compared to WT BBMV. To identify potential proteins associated with Cry11A resistance, not only transcript changes in the larval midgut were analyzed using Illumina sequencing and qPCR, but alterations of previously identified receptor proteins were investigated using immunoblots. The transcripts of 375 genes were significantly increased and those of 208 genes were down regulated in the resistant larvae midgut compared to the WT. None of the transcripts for previously identified receptors of Cry11Aa (Aedes cadherin, ALP1, APN1, and APN2) were altered in these analyses. The genes for the identified functional receptors in resistant larvae midgut did not contain any mutation in their sequences nor was there any change in their transcript expression levels compared to WT. However, ALP proteins were expressed at reduced levels (∼ 40%) in the resistant strain BBMV. APN proteins and their activity were also slightly reduced in resistance strain. The transcript levels of ALPs (AAEL013330 and AAEL015070) and APNs (AAEL008158, AAEL008162) were significantly reduced. These results strongly suggest that ALPs and APNs could be associated with Cry11Aa resistance in Ae. aegypti.
Collapse
Affiliation(s)
- Su-Bum Lee
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA; Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Karlygash G Aimanova
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Sarjeet S Gill
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA; Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA.
| |
Collapse
|
8
|
Stalinski R, Tetreau G, Gaude T, Després L. Pre-selecting resistance against individual Bti Cry toxins facilitates the development of resistance to the Bti toxins cocktail. J Invertebr Pathol 2014; 119:50-3. [PMID: 24768915 DOI: 10.1016/j.jip.2014.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/10/2014] [Accepted: 04/03/2014] [Indexed: 01/16/2023]
Abstract
The bioinsecticide Bacillus thuringiensis subsp. israelensis is a larvicide used worldwide for mosquito control, which contains three Cry toxins and one Cyt toxin. We investigated for the first time in Aedes aegypti (1) the evolution of resistance and cross-resistance of strains selected with each Cry toxin, and (2) the effect of pre-selection with Cry toxin on the evolution of resistance to a mix of Bti toxins. Cross resistance was higher between Cry4Ba and Cry11Aa than between Cry4Aa and either Cry4Ba or Cry11Aa, suggesting both common and specific mechanisms of resistance. Pre-selecting resistance to each Cry toxins facilitated the development of resistance to the full Bti toxins cocktail.
Collapse
Affiliation(s)
- Renaud Stalinski
- Laboratoire d'Ecologie Alpine, CNRS-UMR 5553, Université Joseph Fourier, BP 53, 38041 Grenoble cedex 09, France.
| | - Guillaume Tetreau
- Laboratoire d'Ecologie Alpine, CNRS-UMR 5553, Université Joseph Fourier, BP 53, 38041 Grenoble cedex 09, France; Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA.
| | - Thierry Gaude
- Laboratoire d'Ecologie Alpine, CNRS-UMR 5553, Université Joseph Fourier, BP 53, 38041 Grenoble cedex 09, France.
| | - Laurence Després
- Laboratoire d'Ecologie Alpine, CNRS-UMR 5553, Université Joseph Fourier, BP 53, 38041 Grenoble cedex 09, France.
| |
Collapse
|
9
|
Wirth MC, Berry C, Walton WE, Federici BA. Mtx toxins from Lysinibacillus sphaericus enhance mosquitocidal cry-toxin activity and suppress cry-resistance in Culex quinquefasciatus. J Invertebr Pathol 2013; 115:62-7. [PMID: 24144574 DOI: 10.1016/j.jip.2013.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/27/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022]
Abstract
The interaction of Mtx toxins from Lysinibacillus sphaericus (formerly Bacillus sphaericus) with Bacillus thuringiensis subsp. israelensis Cry toxins and the influence of such interactions on Cry-resistance were evaluated in susceptible and Cry-resistant Culex quinquefasciatus larvae. Mtx-1 and Mtx-2 were observed to be active against both susceptible and resistant mosquitoes; however varying levels of cross-resistance toward Mtx toxins were observed in the resistant mosquitoes. A 1:1 mixture of either Mtx-1 or Mtx-2 with different Cry toxins generally showed moderate synergism, but some combinations were highly toxic to resistant larvae and suppressed resistance. Toxin synergy has been demonstrated to be a powerful tool for enhancing activity and managing Cry-resistance in mosquitoes, thus Mtx toxins may be useful as components of engineered bacterial larvicides.
Collapse
Affiliation(s)
- Margaret C Wirth
- Department of Entomology, University of California, Riverside, CA 92521, United States.
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Cardiff Wales CF10 3AT, United Kingdom
| | - William E Walton
- Department of Entomology, University of California, Riverside, CA 92521, United States
| | - Brian A Federici
- Department of Entomology, University of California, Riverside, CA 92521, United States; Interdepartmental Graduate Programs in Microbiology and Genetics, Genomics and Bioinformatics University of California, Riverside, CA 92521, United States
| |
Collapse
|
10
|
Wirth MC, Walton WE, Federici BA. Inheritance, stability, and dominance of cry resistance in Culex quinquefasciatus (Diptera: Culicidae) selected with the three cry toxins of Bacillus thuringiensis subsp. israelensis. JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:886-894. [PMID: 22897049 DOI: 10.1603/me11192] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Mendelian crosses were used to study the mode of inheritance of Cry toxin resistance in a Culex quinquefasciatus Say (Diptera: Culicidae) colony (CqAB11A) that evolved insecticide resistance under laboratory selection with a deletion mutant of Bacillus thuringiensis subsp. israelensis de Barjac lacking the Cyt1Aa toxin component but containing its three major Cry toxins, Cry4Aa, Cry4Ba, and Cry11Aa. High levels of resistance were observed to Cry toxins. F1 offspring of reciprocal crosses to a sensitive colony showed intermediate levels of resistance with no maternal effect, indicating autosomal inheritance. Dose-response data for backcross offspring deviated significantly from the monofactorial model when tested with Cry4Aa + Cry4Ba + Cry11Aa, Cry4Aa + Cry4Ba, or Cry11Aa. However, tests with Cry11Ba from B. thuringiensis subsp. jegathesan (Seleena, Lee, Lecadet) fit the monofactorial model. Dominance of F1 offspring was calculated at different concentrations of Cry-toxin suspensions and, as reported for other Cry-resistant Culex, generally decreased as concentration increased. A subset of colony CqAB11A was reared without selection pressure for 18 generations with little change in susceptibility, indicating a highly homozygous population. Consistent with reports for other Cry-resistant Culex, the data show these mosquitoes evolved resistance to B. thuringiensis Cry toxins at multiple loci in response to selection pressure and that cross-resistance to Cry11Ba was conferred by one of those loci.
Collapse
Affiliation(s)
- Margaret C Wirth
- Department of Entomology, University of California-Riverside, Riverside, CA 92521, USA.
| | | | | |
Collapse
|
11
|
The 60-kilodalton protein encoded by orf2 in the cry19A operon of Bacillus thuringiensis subsp. jegathesan functions like a C-terminal crystallization domain. Appl Environ Microbiol 2012; 78:2005-12. [PMID: 22247140 DOI: 10.1128/aem.06750-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cry19A operon of Bacillus thuringiensis subsp. jegathesan encodes two proteins, mosquitocidal Cry19A (ORF1; 75 kDa) and an ORF2 (60 kDa) of unknown function. Expression of the cry19A operon in an acrystalliferous strain of B. thuringiensis (4Q7) yielded one small crystal per cell, whereas no crystals were produced when cry19A or orf2 was expressed alone. To determine the function of the ORF2 protein, different combinations of Cry19A, ORF2, and the N- or C-terminal half of Cry1C were synthesized in strain 4Q7. Stable crystalline inclusions of these fusion proteins similar in shape to those in the strain harboring the wild-type operon were observed in sporulating cells. Comparative analysis showed that ORF2 shares considerable amino acid sequence identity with the C-terminal region of large Cry proteins. Together, these results suggest that ORF2 assists in synthesis and crystallization of Cry19A by functioning like the C-terminal domain characteristic of Cry protein in the 130-kDa mass range. In addition, to determine whether overexpression of the cry19A operon stabilized its shape and increased Cry19A yield, it was expressed under the control of the strong chimeric cyt1A-p/STAB-SD promoter. Interestingly, in contrast to the expression seen with the native promoter, overexpression of the operon yielded uniform bipyramidal crystals that were 4-fold larger on average than the wild-type crystal. In bioassays using the 4th instar larvae of Culex quinquefasciatus, the strain producing the larger Cry19A crystal showed moderate larvicidal activity that was 4-fold (95% lethal concentration [LC(95)] = 1.9 μg/ml) more toxic than the activity produced in the strain harboring the wild-type operon (LC(95) = 8.2 μg/ml).
Collapse
|
12
|
POOPATHI SUBBIAH, ABIDHA SURESH. The use of clarified butter sediment waste from dairy industries for the production of mosquitocidal bacteria. INT J DAIRY TECHNOL 2011. [DOI: 10.1111/j.1471-0307.2011.00745.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
13
|
Paris M, Tetreau G, Laurent F, Lelu M, Despres L, David JP. Persistence of Bacillus thuringiensis israelensis (Bti) in the environment induces resistance to multiple Bti toxins in mosquitoes. PEST MANAGEMENT SCIENCE 2011; 67:122-128. [PMID: 21162152 DOI: 10.1002/ps.2046] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 04/28/2010] [Accepted: 07/20/2010] [Indexed: 05/30/2023]
Abstract
BACKGROUND The simultaneous production of six different toxins by Bacillus thuringiensis israelensis (Bti) is thought to delay the evolution of resistance in treated mosquito populations. Recent studies have shown that Bti can persist and proliferate in the environment, thereby imposing continuous selective pressure on mosquito populations, raising concerns about the long-term effectiveness of this bioinsecticide. In order to evaluate the effect of Bti persistence on the evolution of resistance, the authors selected a laboratory Aedes aegypti L. strain with field-collected leaf litter containing Bti toxins. RESULTS It is shown that resistance to each individual Bti toxin (up to 30-fold) can be obtained after only a few generations of selection. However, the resistance to commercial Bti and to environmental Bti remains low (twofold and 3.4-fold respectively) in the selected strain. Furthermore, some selected individuals exhibited resistance to Cry4B but not to Cry4A, suggesting that two distinct resistance mechanisms are involved in the resistance to these two toxins. CONCLUSION Considering that resistance to Cry toxins might act as a first step to resistance to a complete Bti toxin mixture, the present results highlight the importance of testing each toxin individually in order accurately to monitor Bti toxin resistance evolution in field populations.
Collapse
Affiliation(s)
- Margot Paris
- Laboratoire d'Ecologie Alpine, UMR 5553 CNRS-Université de Grenoble, Grenoble, France
| | | | | | | | | | | |
Collapse
|
14
|
Wirth MC, Walton WE, Federici BA. Inheritance patterns, dominance, stability, and allelism of insecticide resistance and cross-resistance in two colonies of Culex quinquefasciatus (Diptera: Culicidae) selected with cry toxins from Bacillus thuringiensis subsp, israelensis. JOURNAL OF MEDICAL ENTOMOLOGY 2010; 47:814-822. [PMID: 20939376 DOI: 10.1603/me09227] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Mendelian crosses were used to analyze the patterns of inheritance of Cry-toxin resistance in two colonies of Culex quinquefasciatus Say larvae resistant to bacterial toxins produced by Bacillus thuringiensis subsp. israelensis de Barjac. Resistance levels exceeded 1000-fold at 95% lethal concentration of the CryllAa-resistant colony (Cq11A). F1 offspring of reciprocal crosses to a susceptible colony revealed autosomal inheritance and offspring were intermediate in resistance to the susceptible and resistant parental lines. Dose-response tests on backcross offspring were consistent with polyfactorial inheritance of resistance toward CryllAa and Cry4Aa + Cry4Ba, whereas cross-resistance toward CryllBa best fit a monofactorial model. Resistance was 600-fold at 95% lethal concentration in the colony selected with Cry4A + Cry4B (Cq4AB). Inheritance of resistance in F1 offspring was autosomal and intermediate to the susceptible and resistant parents. Inheritance of Cry4Aa + Cry4Ba and CryllBa resistance best fit a polyfactorial model in offspring of the Cq4AB backcross, whereas CryllAa-resistance inheritance fit a monofactorial model. Dominance values were calculated at different Cry-toxin concentrations for F, offspring of both resistant colonies; dominance generally decreased as treatment concentration increased. Resistance and cross-resistance remained stable in CqllA and Cq4AB in the absence of insecticide pressure. Allelic complementation tests were complementary and suggested that CqllA and Cq4AB evolved resistance to Cry toxins at common loci. The patterns of cross-resistance suggest cross-recognition of binding moieties by CryllAa, Cry4Aa + Cry4Ba, and CryllBa in these Culex, which may be partly responsible for the toxin synergy characteristic of B. thuringiensis subsp. israelensis de Barjac.
Collapse
Affiliation(s)
- Margaret C Wirth
- Department of Entomology, University of California, Riverside, CA 92521, USA.
| | | | | |
Collapse
|
15
|
Chaki PP, Govella NJ, Shoo B, Hemed A, Tanner M, Fillinger U, Killeen GF. Achieving high coverage of larval-stage mosquito surveillance: challenges for a community-based mosquito control programme in urban Dar es Salaam, Tanzania. Malar J 2009; 8:311. [PMID: 20042071 PMCID: PMC2806382 DOI: 10.1186/1475-2875-8-311] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 12/30/2009] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Preventing malaria by controlling mosquitoes in their larval stages requires regular sensitive monitoring of vector populations and intervention coverage. The study assessed the effectiveness of operational, community-based larval habitat surveillance systems within the Urban Malaria Control Programme (UMCP) in urban Dar es Salaam, Tanzania. METHODS Cross-sectional surveys were carried out to assess the ability of community-owned resource persons (CORPs) to detect mosquito breeding sites and larvae in areas with and without larviciding. Potential environmental and programmatic determinants of habitat detection coverage and detection sensitivity of mosquito larvae were recorded during guided walks with 64 different CORPs to assess the accuracy of data each had collected the previous day. RESULTS CORPs reported the presence of 66.2% of all aquatic habitats (1,963/2,965), but only detected Anopheles larvae in 12.6% (29/230) of habitats that contained them. Detection sensitivity was particularly low for late-stage Anopheles (2.7%, 3/111), the most direct programmatic indicator of malaria vector productivity. Whether a CORP found a wet habitat or not was associated with his/her unfamiliarity with the area (Odds Ratio (OR) [95% confidence interval (CI)] = 0.16 [0.130, 0.203], P < 0.001), the habitat type (P < 0.001) or a fence around the compound (OR [95%CI] = 0.50 [0.386, 0.646], P < 0.001). The majority of mosquito larvae (Anophelines 57.8% (133/230) and Culicines 55.9% (461/825) were not reported because their habitats were not found. The only factor affecting detection of Anopheline larvae in habitats that were reported by CORPs was larviciding, which reduced sensitivity (OR [95%CI] = 0.37 [0.142, 0.965], P = 0.042). CONCLUSIONS Accessibility of habitats in urban settings presents a major challenge because the majority of compounds are fenced for security reasons. Furthermore, CORPs under-reported larvae especially where larvicides were applied. This UMCP system for larval surveillance in cities must be urgently revised to improve access to enclosed compounds and the sensitivity with which habitats are searched for larvae.
Collapse
Affiliation(s)
- Prosper P Chaki
- Ifakara Health Institute, Coordination Office, Kiko Avenue, Mikocheni, PO Box 78373, Dar es Salaam, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Vector Group, Pembroke Place, Liverpool, L3 5QA, UK
- Durham University, School of Biological and Biomedical Sciences, South Road, Durham, DH1 3LE, UK
| | - Nicodem J Govella
- Ifakara Health Institute, Coordination Office, Kiko Avenue, Mikocheni, PO Box 78373, Dar es Salaam, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Vector Group, Pembroke Place, Liverpool, L3 5QA, UK
- Durham University, School of Biological and Biomedical Sciences, South Road, Durham, DH1 3LE, UK
| | - Bryson Shoo
- Dar es Salaam City Council, Ministry of Regional Administration and Local Government, United Republic of Tanzania
| | - Abdullah Hemed
- Dar es Salaam City Council, Ministry of Regional Administration and Local Government, United Republic of Tanzania
| | - Marcel Tanner
- Department of Public Health and Epidemiology, Swiss Tropical Institute, Basel, Switzerland
| | - Ulrike Fillinger
- Durham University, School of Biological and Biomedical Sciences, South Road, Durham, DH1 3LE, UK
- London School of Hygiene and Tropical Medicine, Disease Control & Vector Biology Unit, Keppel Street, London, WC1E 7HT, UK
| | - Gerry F Killeen
- Ifakara Health Institute, Coordination Office, Kiko Avenue, Mikocheni, PO Box 78373, Dar es Salaam, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Vector Group, Pembroke Place, Liverpool, L3 5QA, UK
- Durham University, School of Biological and Biomedical Sciences, South Road, Durham, DH1 3LE, UK
| |
Collapse
|
16
|
Aedes aegypti cadherin serves as a putative receptor of the Cry11Aa toxin from Bacillus thuringiensis subsp. israelensis. Biochem J 2009; 424:191-200. [PMID: 19732034 DOI: 10.1042/bj20090730] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cry11Aa of Bacillus thuringiensis subsp. israelensis is the most active toxin to Aedes aegypti in this strain. We previously reported that, in addition to a 65 kDa GPI (glycosylphosphatidylinositol)-anchored ALP (alkaline phosphatase), the toxin also binds a 250 kDa membrane protein. Since this protein is the same size as cadherin, which in lepidopteran insects is an important Cry toxin receptor, we developed an anti-AaeCad antibody. This antibody detects a 250 kDa protein in immunoblots of larval BBMVs (brush border membrane vesicles). The antibody inhibits Cry11Aa toxin binding to BBMVs and immunolocalizes the cadherin protein to apical membranes of distal and proximal caecae and posterior midgut epithelial cells. This localization is consistent with areas to which Cry11Aa toxin binds and causes pathogenicity. Therefore, the full-length Aedes cadherin cDNA was isolated from Aedes larvae and partial overlapping fragments that covered the entire protein were expressed in Escherichia coli. Using toxin overlay assays, we showed that one cadherin fragment, which contains CR7-11 (cadherin repeats 7-11), bound Cry11Aa and this binding was primarily through toxin domain II loops alpha8 and 2. Cadherin repeats CR8-11 but not CR7 bound Cry11Aa under non-denaturing conditions. Cry11Aa bound the cadherin fragment with high affinity with an apparent Kd of 16.7 nM. Finally we showed that this Cry11Aa-binding site could also be competed by Cry11Ba and Cry4Aa but not Cry4Ba. These results indicate that Aedes cadherin is possibly a receptor for Cry11A and, together with its ability to bind an ALP, suggest a similar mechanism of toxin action as previously proposed for lepidopteran insects.
Collapse
|
17
|
Frutos R, Rang C, Royer M. Managing Insect Resistance to Plants ProducingBacillus thuringiensisToxins. Crit Rev Biotechnol 2008. [DOI: 10.1080/0738-859991229251] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
18
|
Prabakaran G, Hoti SL. Immobilization of Alginate-Encapsulated Bacillus thuringiensis var. israelensis Containing Different Multivalent Counterions for Mosquito Control. Curr Microbiol 2008. [DOI: 10.1007/s00284-008-9159-z#page-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
|
19
|
Influence of amino nitrogen in the culture medium enhances the production of δ-endotoxin and biomass of Bacillus thuringiensis var. israelensis for the large-scale production of the mosquito control agent. J Ind Microbiol Biotechnol 2008; 35:961-5. [DOI: 10.1007/s10295-008-0370-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Accepted: 05/09/2008] [Indexed: 10/22/2022]
|
20
|
Prabakaran G, Hoti SL. Immobilization of alginate-encapsulated Bacillus thuringiensis var. israelensis containing different multivalent counterions for mosquito control. Curr Microbiol 2008; 57:111-4. [PMID: 18389308 DOI: 10.1007/s00284-008-9159-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 02/28/2008] [Indexed: 11/29/2022]
Abstract
Immobilized techniques have been used widely for the controlled release formulation of mosquitoes. Among the microbial formulations, polymeric matrices play an important role in the controlled release of microbial pesticide at rates sufficiently effective to kill mosquitoes in the field. The advantage of these matrices is that they enhance the stability of both spores and toxin against pH, temperature variations, and UV irradiation. The disadvantage of using calcium alginate beads is that they are unstable upon contact with phosphate of potassium or sodium ions rich in the mosquito habitats. To overcome these problems, attempts were made to encapsulate Bacillus thuringiensis var. israelensis within alginate by using different multivalent counterions, namely, calcium chloride, zinc sulfate, copper sulfate, cobalt chloride, and ferric chloride, and the beads formed were tested for its mosquito larvicidal activity. Among all the beads tested, zinc alginate beads resulted in maximum larvicidal activity of 98% (+/-1.40 SE) against Culex quinquefasciatus IIIrd instar larvae and maximum spore count of 3.36 x 10(5) (+/-5291.50 SE) CFU/ml. Zinc alginate beads maintained their structure for up to 48 h when shaken vigorously on a rotary shaker at 180 rpm in the presence of 10 mM potassium phosphate buffer (pH 6.8 +/- 0.1). In conclusion, our results suggest that the use of zinc sulfate as counterions to encapsulate B. thuringiensis var. israelensis within alginate may be a potent mosquito control program in the habitats where more phosphate ions are present.
Collapse
Affiliation(s)
- G Prabakaran
- Vector Control Research Centre, Indian Council of Medical Research, Indira Nagar, Puducherry 605006, India.
| | | |
Collapse
|
21
|
Prabakaran G, Hoti S, Manonmani A, Balaraman K. Coconut water as a cheap source for the production of delta endotoxin of Bacillus thuringiensis var. israelensis, a mosquito control agent. Acta Trop 2008; 105:35-8. [PMID: 17963708 DOI: 10.1016/j.actatropica.2007.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 08/29/2007] [Accepted: 09/14/2007] [Indexed: 10/22/2022]
Abstract
Bacillus thuringiensis var. israelensis (B. t. i.) is being widely used in mosquito control programs. However, the large-scale production of this bacillus is expensive due to the high cost of the production medium. In this study, we attempted to develop a cost-effective medium, based on a locally available raw material namely coconut water which is available in plenty as waste product from coconut oil industry. The yield of cell mass, sporulation and mosquito larvicidal activity were studied by growing this bacterium in this waste product and in comparison with the conventional medium (NYSM). Cell mass yield of 3.1g/L, spore count of 3.4x10(11)spores/mL and mosquito larvicidal activity (LC(50)) of 14.85ng/mL (against early fourth-instar larvae of Aedes aegypti) were obtained with a 30h old culture of this bacterium grown in coconut water. This is almost similar to that obtained with NYSM medium. Hence, coconut water-based culture medium is economical for the production of B. t. i.
Collapse
|
22
|
Prabakaran G, Hoti SL. Immobilization in alginate as a technique for the preservation of Bacillus thuringiensis var. israelensis for long-term preservation. J Microbiol Methods 2007; 72:91-4. [PMID: 18054810 DOI: 10.1016/j.mimet.2007.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 10/25/2007] [Accepted: 11/02/2007] [Indexed: 11/29/2022]
Abstract
Technique for immobilization using sodium alginate as the matrix to preserve Bacillus thuringiensis var. israelensis isolates for long time storage was developed. Two strains of B. thuringiensis var. israelensis viz., VCRC B-17 and WHO standard strain IPS-82 were immobilized in alginate matrix and preserved at 4 degrees C and when tested both were found to have maintained excellent viability and mosquito larvicidal activity for 10 years. Mosquito larvicidal activity of B-17 and IPS-82 alginate beads, in term of LC(50) values before storage was 72.07 ng/ml and 47.07 ng/ml, respectively and after storage at 4 degrees C for a period of 1 to 10 years the values ranged from 69.88 to 73.86 ng/ml with a mean of 72.38 ng/ml and 45.32 to 48.60 ng/ml with a mean of 47.49 ng/ml, respectively. Similarly spore count of the beads of the respective strains was 4.37 x 10(8) and 3.33 x 10(10) CFU/mg before storage. After storage at 4 degrees C for a period of 1 to 10 years the counts of the beads of the respective strains ranged from 4.23 x 10(8) to 4.83 x 10(8) CFU/mg (mean of 4.49 x 10(8) CFU/mg) and 3.2 x 10(10) to 3.87 x 10(10) CFU/mg (mean of 3.54 x 10(10) CFU/mg). The alginate matrix immobilization technique has many advantages over free cells are that they enhance the stability of both spores and toxin against several physicochemical conditions and confer reduced susceptibility to contamination.
Collapse
Affiliation(s)
- G Prabakaran
- Vector Control Research Centre (Indian Council of Medical Research) Indira Nagar, Puducherry, India.
| | | |
Collapse
|
23
|
Promdonkoy B, Promdonkoy P, Panyim S. Co-expression of Bacillus thuringiensis Cry4Ba and Cyt2Aa2 in Escherichia coli revealed high synergism against Aedes aegypti and Culex quinquefasciatus larvae. FEMS Microbiol Lett 2005; 252:121-6. [PMID: 16168580 DOI: 10.1016/j.femsle.2005.08.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 06/29/2005] [Accepted: 08/25/2005] [Indexed: 11/28/2022] Open
Abstract
Cry4Ba is a delta-endotoxin produced by Bacillus thuringiensis subsp. israelensis and Cyt2Aa2 is a cytolytic delta-endotoxin produced by B. thuringiensis subsp. darmstadiensis. Cry4Ba produced in Escherichia coli was toxic to Aedes aegypti larvae (LC(50)=140 ng ml(-1)) but virtually inactive to Culex quinquefasciatus larvae. Cyt2Aa2 expressed in E. coli exhibited moderate activity against A. aegypti and C. quinquefasciatus larvae with LC(50) values of 350 and 250 ng ml(-1), respectively. Co-expression of both toxins in E. coli dramatically increased toxicity to both A. aegypti andC. quinquefasciatus larvae (LC(50)=7 and 20 ng ml(-1), respectively). This is the first report to demonstrate that Cry4Ba and Cyt2Aa2 have high synergistic activity against C. quinquefasciatus larvae.
Collapse
Affiliation(s)
- Boonhiang Promdonkoy
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand.
| | | | | |
Collapse
|
24
|
Abstract
The Cry family of Bacillus thuringiensis insecticidal and nematicidal proteins constitutes a valuable source of environmentally benign compounds for the control of insect pests and disease agents. An understanding of Cry toxin resistance at a molecular level will be critical to the long-term utility of this technology; it may also shed light on basic mechanisms used by other bacterial toxins that target specific organisms or cell types. Selection and cross-resistance studies have confirmed that genetic adaptation can elicit varying patterns of Cry toxin resistance, which has been associated with deficient protoxin activation by host proteases, and defective Cry toxin-binding cell surface molecules, such as cadherins, aminopeptidases and glycolipids. Recent work also suggests Cry toxin resistance may be induced in invertebrates as an active immune response. The use of model invertebrates, such as Caenorhabditis elegans and Drosophila melanogaster, as well as advances in insect genomics, are likely to accelerate efforts to clone Cry toxin resistance genes and come to a detailed and broad understanding of Cry toxin resistance.
Collapse
Affiliation(s)
- Joel S Griffitts
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0349, USA
| | | |
Collapse
|
25
|
Wirth MC, Delécluse A, Walton WE. Laboratory selection for resistance to Bacillus thuringiensis subsp. jegathesan or a component toxin, Cry11B, in Culex quinquefasciatus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2004; 41:435-441. [PMID: 15185947 DOI: 10.1603/0022-2585-41.3.435] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The bacteria Bacillus thuringiensis subsp. israelensis and Bacillus sphaericus produce insecticidal toxins used to control mosquito larvae throughout the world. Unfortunately, there are few alternative insecticides with similar activity and environmental safety, which may limit the long-term success of these insecticides. Bacillus thuringiensis subsp. jegathesan is another bacterium with toxins that are active against mosquitoes and has potential for development as a commercial product. B. t. subsp. jegathesan would be ineffective if cross-resistance was detected or if treated mosquito populations evolved resistance. B. t. subsp. jegathesan was evaluated for its potential for selecting insecticide resistance in Culex quinquefasciatus Say. Susceptibility changes in mosquitoes selected with the wild-type strain were compared with susceptibility changes in mosquitoes selected with Cry11B, a component toxin of B. t. subsp. jegathesan. Resistance was detected in generation 18 in the Cry11B-selected colony, reached a maximum of 38-fold, and was present through generation 40. The B. t. subsp. jegathesan-selected colony evolved 13-fold resistance in generation 22, but resistance declined to 2.3-fold in generation 26 and remained low throughout the study. Cry11B-selected mosquitoes showed no significant resistance to the wild-type bacterium, whereas B. t. subsp. jegathesan-selected mosquitoes expressed significant resistance to Cry11B. Both colonies displayed cross-resistance to component toxins of B. t. subsp. israelensis, but they lacked cross-resistance to that wild-type strain. The patterns of resistance and cross-resistance in this study are consistent with the patterns previously observed in mosquitoes selected with B. t. subsp. israelensis and suggest that B. t. subsp. jegathesan might also be at low risk for resistance.
Collapse
Affiliation(s)
- Margaret C Wirth
- Department of Entomology, University of California, Riverside 92521, USA
| | | | | |
Collapse
|
26
|
Ruiz LM, Segura C, Trujillo J, Orduz S. In vivo binding of the Cry11Bb toxin of Bacillus thuringiensis subsp. medellin to the midgut of mosquito larvae (Diptera: Culicidae). Mem Inst Oswaldo Cruz 2004; 99:73-9. [PMID: 15057351 DOI: 10.1590/s0074-02762004000100013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Bacillus thuringiensis subsp. medellin produces numerous proteins among which 94 kDa known as Cry11Bb, has mosquitocidal activity. The mode of action of the Cry11 proteins has been described as similar to those of the Cry1 toxins, nevertheless, the mechanism of action is still not clear. In this study we investigated the in vivo binding of the Cry11Bb toxin to the midgut of the insect species Anopheles albimanus, Aedes aegypti, and Culex quinquefasciatus by immunohistochemical analysis. Spodoptera frugiperda was included as negative control. The Cry11Bb protein was detected on the apical microvilli of the midgut epithelial cells, mostly on the posterior midgut and gastric caeca of the three mosquito species. Additionally, the toxin was detected in the Malpighian tubules of An. albimanus, Ae. aegypti, Cx. quinquefasciatus, and in the basal membrane of the epithelial cells of Ae. aegypti midgut. No toxin accumulation was observed in the peritrophic membrane of any of the mosquito species studied. These results confirm that the primary site of action of the Cry11 toxins is the apical membrane of the midgut epithelial cells of mosquito larvae.
Collapse
Affiliation(s)
- Lina María Ruiz
- Unidad de Biotecnología y Control Biológico, Corporación para Investigaciones Biológicas, Medellín, Colombia
| | | | | | | |
Collapse
|
27
|
Khasdan V, Ben-Dov E, Manasherob R, Boussiba S, Zaritsky A. Toxicity and synergism in transgenic Escherichia coli expressing four genes from Bacillus thuringiensis subsp. israelensis. Environ Microbiol 2001; 3:798-806. [PMID: 11846773 DOI: 10.1046/j.1462-2920.2001.00253.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The genes cyt1Aa and p20, encoding, respectively, cytolytic and accessory proteins of Bacillus thuringiensis subsp. israelensis, were introduced into previously constructed clones expressing cry4Aa and cry11Aa in Escherichia coli (Ben-Dov et al., 1995). Fifteen clones with all possible combinations of the four genes were obtained and found to express the genes included. Two new combinations, pVE4-ADRC and pVE4-ARC, expressing cyt1Aa, p20 and cry4Aa, with or without cry11Aa, respectively, were more toxic than their counterparts without cyt1Aa. They displayed the highest toxicity against Aedes aegypti larvae ever reached in transgenic bacteria. Five out of the six clones (except pVE4-DC) containing cry4Aa or cry11Aa (with or without p20) displayed varying levels of synergism with cyt1Aa: they are 1.5-to 34-fold more toxic than the respective clones without cyt1Aa against exposed larvae. Their lethal times also decreased (they kill larvae quicker), more so at higher cell concentrations. These clones are anticipated to dramatically reduce the likelihood of resistant development in the target organisms (Wirth et al., 1997).
Collapse
Affiliation(s)
- V Khasdan
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva 84105, Israel
| | | | | | | | | |
Collapse
|
28
|
Sayyed AH, Crickmore N, Wright DJ. Cyt1Aa from Bacillus thuringiensis subsp. israelensis is toxic to the diamondback moth, Plutella xylostella, and synergizes the activity of Cry1Ac towards a resistant strain. Appl Environ Microbiol 2001; 67:5859-61. [PMID: 11722947 PMCID: PMC93384 DOI: 10.1128/aem.67.12.5859-5861.2001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Bacillus thuringiensis subsp. israelensis cytolytic protein Cyt1Aa was found to be toxic to an insecticide-susceptible laboratory population of Plutella xylostella. Cry1Ac-resistant populations of P. xylostella showed various degrees of resistance to Cyt1Aa. Cyt1Aa/Cry1Ac mixtures showed a marked level of synergism in the Cry1Ac-resistant populations.
Collapse
Affiliation(s)
- A H Sayyed
- Department of Biological Sciences, Imperial College of Science, Technology and Medicine, Silwood Park, Ascot, Berkshire SL5 7PY, United Kingdom
| | | | | |
Collapse
|
29
|
Regis L, Silva-Filha MH, Nielsen-LeRoux C, Charles JF. Bacteriological larvicides of dipteran disease vectors. Trends Parasitol 2001; 17:377-80. [PMID: 11685898 DOI: 10.1016/s1471-4922(01)01953-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The apparent success in vector control observed between 1950 and 1970 was followed by worldwide resistance to organosynthetic insecticides wherever they were used intensively. Insect resistance to one or more categories of insecticides has limited the effectiveness of these compounds, and their non-selective mode of action adversely affects non-target organisms. This scenario highlights the need for selective agents in integrated vector control programs. This article gives an overview of the main fundamental and applied research topics on entomopathogenic bacteria in relation to their role in vector control.
Collapse
Affiliation(s)
- L Regis
- Fundação Oswaldo Cruz-Fiocruz, CPqAM, Dept Entomology, Av Moraes Rego s/n 50670.420 Recife, PE, Brazil.
| | | | | | | |
Collapse
|
30
|
Wirth MC, Delécluse A, Walton WE. Lack of cross-resistance to Cry19A from Bacillus thuringiensis subsp. jegathesan in Culex quinquefasciatus (Diptera: Culicidae) resistant to cry toxins from Bacillus thuringiensis subsp. israelensis. Appl Environ Microbiol 2001; 67:1956-8. [PMID: 11282656 PMCID: PMC92820 DOI: 10.1128/aem.67.4.1956-1958.2001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Culex quinquefasciatus mosquitoes with high levels of resistance to single or multiple toxins from Bacillus thuringiensis subsp. israelensis were tested for cross-resistance to the Bacillus thuringiensis subsp. jegathesan polypeptide Cry19A. No cross-resistance was detected in mosquitoes that had been selected with the Cry11A, Cry4A and Cry4B, or Cry4A, Cry4B, Cry11A, and CytA toxins. A low but statistically significant level of cross-resistance, three to fourfold, was detected in the colony selected with Cry4A, Cry4B, and Cry11A. This cross-resistance was similar to that previously detected with B. thuringiensis subsp. jegathesan in the same colony. These data help explain the toxicity of B. thuringiensis subsp. jegathesan against the resistant colonies and indicate that the Cry19A polypeptide might be useful in managing resistance and/or as a component of synthetic combinations of mosquitocidal toxins.
Collapse
Affiliation(s)
- M C Wirth
- Department of Entomology, University of California, Riverside, CA 92521, USA.
| | | | | |
Collapse
|
31
|
Wirth MC, Federici BA, Walton WE. Cyt1A from Bacillus thuringiensis synergizes activity of Bacillus sphaericus against Aedes aegypti (Diptera: Culicidae). Appl Environ Microbiol 2000; 66:1093-7. [PMID: 10698776 PMCID: PMC91947 DOI: 10.1128/aem.66.3.1093-1097.2000] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus sphaericus is a mosquitocidal bacterium recently developed as a commercial larvicide that is used worldwide to control pestiferous and vector mosquitoes. Whereas B. sphaericus is highly active against larvae of Culex and Anopheles mosquitoes, it is virtually nontoxic to Aedes aegypti, an important vector species. In the present study, we evaluated the capacity of the cytolytic protein Cyt1A from Bacillus thuringiensis subsp. israelensis to enhance the toxicity of B. sphaericus toward A. aegypti. Various combinations of these two materials were evaluated, and all were highly toxic. A ratio of 10:1 of B. sphaericus to Cyt1A was 3, 600-fold more toxic to A. aegypti than B. sphaericus alone. Statistical analysis showed this high activity was due to synergism between the Cyt1A toxin and B. sphaericus. These results suggest that Cyt1A could be useful in expanding the host range of B. sphaericus.
Collapse
Affiliation(s)
- M C Wirth
- Department of Entomology, University of California, Riverside, California 92521, USA.
| | | | | |
Collapse
|