Intestinal Bacteria Affect Growth of Bacillus thuringiensis in Larvae of the Oriental Tea Tortrix, Homona magnanima Diakonoff (Lepidoptera: Tortricidae)

Takatsuka, Jun; Kunimi, Yasuhisa

doi:10.1006/jipa.2000.4973

Cited by 57 publications

(42 citation statements)

References 13 publications

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“…The observation that B. thuringiensis replicates within M. sexta cadavers at the expense of gut bacteria is in agreement with data from other studies that demonstrated such competition in lepidoptera (18,33,34) and diptera (1). The presence of gut bacteria may afford larvae some protection since aseptic larvae that had been exposed to antibiotics only during first instar were killed more rapidly by DiPel than were nonsterile larvae.…”

Section: Discussionsupporting

confidence: 90%

“…The presence of gut bacteria may afford larvae some protection since aseptic larvae that had been exposed to antibiotics only during first instar were killed more rapidly by DiPel than were nonsterile larvae. The presence of gut bacteria was associated with a slight delay in mortality in synergism bioassays, which may be (20,34). The level of Cry toxicity may be increased (25), decreased (32), or unaffected (19) by the inclusion of antibiotics in lepidopteran bioassays, although the effects of antibiotics on gut bacteria were not reported.…”

Section: Discussionmentioning

confidence: 99%

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Gut Bacteria Are Not Required for the Insecticidal Activity of Bacillus thuringiensis toward the Tobacco Hornworm, Manduca sexta

Johnston

Crickmore

2009

Appl Environ Microbiol

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It was recently proposed that gut bacteria are required for the insecticidal activity of the Bacillus thuringiensis-based insecticide, DiPel, toward the lepidopterans Manduca sexta, Pieris rapae, Vanessa cardui, and Lymantria dispar. Using a similar methodology, it was found that gut bacteria were not required for the toxicity of DiPel or Cry1Ac or for the synergism of an otherwise sublethal concentration of Cry1Ac toward M. sexta. The toxicities of DiPel and of B. thuringiensis HD73 Cry ؊ spore/Cry1Ac synergism were attenuated by continuously exposing larvae to antibiotics before bioassays. Attenuation could be eliminated by exposing larvae to antibiotics only during the first instar without altering larval sterility. Prior antibiotic exposure did not attenuate Cry1Ac toxicity. The presence of enterococci in larval guts slowed mortality resulting from DiPel exposure and halved Cry1Ac toxicity but had little effect on B. thuringiensis HD73 Cry ؊ spore/Cry1Ac synergism. B. thuringiensis Cry ؊ cells killed larvae after intrahemocoelic inoculation of M. sexta, Galleria mellonella, and Spodoptera litura and grew rapidly in plasma from M. sexta, S. litura, and Tenebrio molitor. These findings suggest that gut bacteria are not required for B. thuringiensis insecticidal activity toward M. sexta but that B. thuringiensis lethality is reduced in larvae that are continuously exposed to antibiotics before bioassay.Bacillus thuringiensis has long been regarded as a bona fide entomopathogen that can produce an array of virulence factors including insecticidal parasporal crystal (Cry) toxins, vegetative insecticidal proteins, phospholipases, immune inhibitors, and antibiotics (31). B. thuringiensis establishes lethal infections in many insect species after intrahemocoelic inoculation (9,10,14,26,31), and the insecticidal activity of Cry toxins, which lyse the intestinal epithelium, can be synergized by the presence of viable B. thuringiensis spores (31). In each instance, synergism has been attributed to hemocoelic infection by B. thuringiensis.A novel hypothesis (6, 7) proposed that B. thuringiensis is incapable of killing Lymantria dispar, Manduca sexta, Pieris rapae, or Vanessa cardui in the absence of gut bacteria. Prior exposure of L. dispar larvae to a combination of four antibiotics severely reduced the subsequent toxicity of the B. thuringiensis-based (spores and Cry toxins) bioinsecticide, DiPel (Valent BioSciences) (6). Both larval susceptibility to B. thuringiensis and the number of culturable gut bacteria were found to be negatively correlated with the concentration of antibiotics to which larvae were previously exposed. Furthermore, a total reduction in larval susceptibility was coincident with the elimination of any detectable gut bacteria. Experimental reinfection with Enterobacter sp. strain NAB3, found in the guts of some populations of L. dispar larvae, was found to rescue the toxicity of B. thuringiensis, whereas reinfection with Enterococcus casseliflavus and Staphylococcus xylosus did not. It was also sho...

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Gut Bacteria Are Not Required for the Insecticidal Activity of Bacillus thuringiensis toward the Tobacco Hornworm, Manduca sexta

Johnston

Crickmore

2009

Appl Environ Microbiol

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“…The cause of the poor reproduction of Btk rif R cadavers killed by this highly pathogenic isolate requires further investigation. However, since cadavers infected with this isolate, when plated out on less selective media (LB) routinely contain high counts of other bacterial species (>10 6 CFU per cadaver) it is likely that heterospecific competition is severely limiting growth in this strain (Takatsuka and Kunimi, 2000).…”

Section: Resultsmentioning

confidence: 99%

Quantifying the reproduction of Bacillus thuringiensis HD1 in cadavers and live larvae of Plutella xylostella

Raymond

Elliot

Ellis

2008

Journal of Invertebrate Pathology

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The Bacillus cereus group comprises a range of micro-organisms with diverse habits, including gut commensals, opportunistic pathogens and soil saprophytes. Using quantitative microbiological methods we tested whether Bacillus thuringiensis (Bt) could reproduce in cadavers of Plutella xylostella killed by Bt, or in the gut of live insects, or be transmitted vertically from females to their offspring. We also tested whether diverse Bt strains could grow in high nutrient broth at a pH similar to that in the larval midgut. Low levels of reproduction were found in insect cadavers but there was no evidence of vertical transmission, or of significant reproduction in live insects. Four strains of B. thuringiensis var. kurstaki and one of B. thuringiensis var. tenebrionis were found to be capable of growth at high pH. Greater spore recovery rates in frass were found in hosts that were resistant or tolerant of infection. We concluded that that spores recovered in frass represent, in general, an ungerminated fraction of ingested inoculum and that germination rates are reduced in unsuitable hosts.

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“…The low recovery of Bt from gut samples in spite of a higher prevalence in fecal pellet cultures is puzzling. This could be explained by intraluminal competition from other bacterial species, which could somehow keep the Bt population low until it passed from the gut to the fecal pellets (Takatsuka and Kunimi 2000), by abiotic inhibitory effects within the gut cavity (Luthy et al 1985, Pang andGrigorten 1998), by simple dormancy of the Bt population while passing through the gut, or by an accumulation of Bt spores in fecal pellets due to the high speed of transit.…”

Section: Discussionmentioning

confidence: 99%

Bacillus thuringiensis in caterpillars and associated materials collected from protected tropical forests in northwestern Costa Rica

Rodríguez-Sánchez

Sittenfeld

Janzen

et al. 2014

RBT

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Abstract. Bacillus thuringiensis (Bt) synthesizes crystalline inclusions that are toxic to caterpillars (Lepidoptera) and other orders of invertebrates. Materials associated with 37 caterpillars from 16 species, collected while feeding on 15 different species of host plants in dry, cloud and rain forests located in the Área de Conservación Guanacaste in northwestern Costa Rica, were examined for the presence of Bt. From a total of 101 derived samples, 25 Bt isolates were cultured: 56% from host plant leaves, 8% from caterpillar guts and 36% from caterpillar fecal pellets. Bt was isolated from at least one sample in 38% of the systems constituted by the food plant, gut and fecal pellets corresponding to a single caterpillar. Four different morphologies of crystalline inclusions were observed, with bipyramidal and irregular crystal morphologies being the most prevalent. Rev. Biol. Trop. 54(2): 265-271. Epub 2006 Jun 01.

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Intestinal Bacteria Affect Growth of Bacillus thuringiensis in Larvae of the Oriental Tea Tortrix, Homona magnanima Diakonoff (Lepidoptera: Tortricidae)

Cited by 57 publications

References 13 publications

Gut Bacteria Are Not Required for the Insecticidal Activity of Bacillus thuringiensis toward the Tobacco Hornworm, Manduca sexta

Gut Bacteria Are Not Required for the Insecticidal Activity of Bacillus thuringiensis toward the Tobacco Hornworm, Manduca sexta

Quantifying the reproduction of Bacillus thuringiensis HD1 in cadavers and live larvae of Plutella xylostella

Bacillus thuringiensis in caterpillars and associated materials collected from protected tropical forests in northwestern Costa Rica

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