Fate of insecticidal<i>Bacillus thuringiensis</i>Cry protein in soil: differences between purified toxin and biopesticide formulation

Hung, Truong Phuc; Truong, Le Van; Binh, Ngo Dinh; Frutos, Roger; Quiquampoix, Hervé; Staunton, Siobhán

doi:10.1002/ps.4262

Cited by 15 publications

(15 citation statements)

References 35 publications

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“…Under these conditions, the protoxin form of Cry1A at 130kD was predominant and stable for at least 3 days before fading (control in Figure 6D, right part of the blot). This observation is in agreement with the fact that the half-life of Cry1A crystals has been estimated at about 1 week in soil or under laboratory conditions at 25°C (Hung et al, 2016). We used the same initial Btk SA11 spore preparation (0h) to feed the flies.…”

Section: Resultssupporting

confidence: 90%

Bacillus thuringiensis Cry1A toxins divert progenitor cells toward enteroendocrine fate by decreasing cell adhesion with intestinal stem cells

Jneid

Loudhaief

Zucchini-Pascal

et al. 2022

Preprint

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Bacillus thuringiensis subsp kurstaki (Btk) is a strong pathogen toward lepidopteran larvae thanks to specific Cry toxins causing leaky gut phenotypes. Hence, Btk is used worldwide as microbial insecticide to fight crop pests. Btk ingested along with food could also threat gut integrity of organisms insensitive to Btk infection. Here we show that Cry1A toxins induce enterocyte death and intestinal stem cell (ISC) proliferation in the midgut of Drosophila melanogaster, an organism non-susceptible to Btk. Surprisingly, a high proportion of ISC's daughter cells differentiates into enteroendocrine cells instead of their initial enterocyte destiny. We show that Cry1A toxins are activated in the midgut and weakened Cadherin-dependent adherens junction between the ISC and its immediate daughter progenitor, leading the latter to adopt an enteroendocrine fate. Hence, though not lethal to non-susceptible organisms, Cry toxins can interfere with conserved cell adhesion mechanisms, thereby disrupting intestinal homeostasis and physiology.

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Section: Resultssupporting

confidence: 90%

Bacillus thuringiensis Cry1A toxins divert progenitor cells toward enteroendocrine fate by decreasing cell adhesion with intestinal stem cells

Jneid

Loudhaief

Zucchini-Pascal

et al. 2022

Preprint

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“…Data also showed that almost all of the applied Btk formulation dose was still present on the leaves surface 72 h after spraying 28 , its amount returning close to environmental levels only 28 days after treatment 29 . Finally, Bt spores can survive in the soil and on different supports for months and even years after application [30][31][32][33] . Bt formulations contain also different compounds to protect spores and crystals and aggregate them into a wettable form, surfactants to facilitate spraying and dispersion on plants, and phagostimulants 34,35 .…”

mentioning

confidence: 99%

Differential side-effects of Bacillus thuringiensis bioinsecticide on non-target Drosophila flies

Babin

Nawrot-Esposito

Gallet

et al. 2020

Sci Rep

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Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.

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“…4 and SANCO/1543/08—rev. 4), knowing that the half-life of the entomopathogenic Cry1 toxins is estimated at ten days in the field [ 47 ]. Therefore, we decided to assess the impacts of the ingestion of two Btk bioinsecticides (i.e., Delfin and Dipel) on the growth and development of Drosophila larvae at two field-realistic concentrations: 5 × 10 6 CFU/g (corresponding to the concentration observed after one spraying) and 5 × 10 7 CFU/g (a concentration which could be reached upon repeated treatments), called hereafter “1X” and “10X”, respectively.…”

Section: Resultsmentioning

confidence: 99%

Bacillus thuringiensis Bioinsecticides Induce Developmental Defects in Non-Target Drosophila melanogaster Larvae

Nawrot-Esposito

Babin

Pasco

et al. 2020

Insects

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Bioinsecticides made from the bacterium Bacillus thuringiensis (Bt) are the bestselling bioinsecticide worldwide. Among Bt bioinsecticides, those based on the strain Bt subsp. kurstaki (Btk) are widely used in farming to specifically control pest lepidopteran larvae. Although there is much evidence of the lack of acute lethality of Btk products for non-target animals, only scarce data are available on their potential non-lethal developmental adverse effects. Using a concentration that could be reached in the field upon sprayings, we show that Btk products impair growth and developmental time of the non-target dipteran Drosophila melanogaster. We demonstrate that these effects are mediated by the synergy between Btk bacteria and Btk insecticidal toxins. We further show that Btk bioinsecticides trigger intestinal cell death and alter protein digestion without modifying the food intake and feeding behavior of the larvae. Interestingly, these harmful effects can be mitigated by a protein-rich diet or by adding the probiotic bacterium Lactobacillus plantarum into the food. Finally, we unravel two new cellular mechanisms allowing the larval midgut to maintain its integrity upon Btk aggression: First the flattening of surviving enterocytes and second, the generation of new immature cells arising from the adult midgut precursor cells. Together, these mechanisms participate to quickly fill in the holes left by the dying enterocytes.

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Fate of insecticidalBacillus thuringiensisCry protein in soil: differences between purified toxin and biopesticide formulation

Cited by 15 publications

References 35 publications

Bacillus thuringiensis Cry1A toxins divert progenitor cells toward enteroendocrine fate by decreasing cell adhesion with intestinal stem cells

Bacillus thuringiensis Cry1A toxins divert progenitor cells toward enteroendocrine fate by decreasing cell adhesion with intestinal stem cells

Differential side-effects of Bacillus thuringiensis bioinsecticide on non-target Drosophila flies

Bacillus thuringiensis Bioinsecticides Induce Developmental Defects in Non-Target Drosophila melanogaster Larvae

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