Synergism between
            <i>Bacillus thuringiensis</i>
            Spores and Toxins against Resistant and Susceptible Diamondback Moths (
            <i>Plutella xylostella</i>
            )

Liu, Yong Biao; Tabashnik, Bruce E.; Moar, William J.; Smith, Robert A.

doi:10.1128/aem.64.4.1385-1389.1998

Cited by 42 publications

(16 citation statements)

References 33 publications

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“…An obligate association with the gut microbiota challenges previous models of the pathogenicity of Bt toxins, and has considerable implications for the ecology of Bt and the evolution of novel resistance mechanisms in invertebrate pests. The gut microbiota hypothesis remains highly controversial, given previous evidence of the lethality Bt in aseptically reared insects (Takatsuka and Kunimi, 2000) and the synergistic action of the Bt spore on the toxicity of crystal toxins in some hosts (Heimpel and Angus, 1959; Li et al ., 1987; Liu et al ., 1998).…”

Section: Introductionmentioning

confidence: 99%

A mid‐gut microbiota is not required for the pathogenicity of Bacillus thuringiensis to diamondback moth larvae

Raymond

Johnston

Wright

et al. 2009

Environmental Microbiology

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A mid-gut microbiota is not required for the pathogenicity of Bacillus 2 thuringiensis to diamondback moth larvae. hosts were not susceptible to B. thuringiensis (Bt) and that inoculation with mid-4 gut bacteria restores pathogenicity. These claims are controversial because 5 larvae were rendered aseptic by consuming antibiotics, although the effect of 6 these antibiotics on Bt was not examined. We tested the generality of the mid-gut 7 bacteria hypothesis in the diamondback moth, Plutella xylostella using properly 8 controlled experiments that investigated the effect of antibiotic consumption and 9 absence of gut microbiota separately. We found that purified Bt toxin and 10 spore/toxin mixtures were fully pathogenic to larvae reared aseptically. 11 Cyt proteins (Schnepf et al., 1998). Bt toxin genes have been widely incorporated into 5 genetically modified insect resistant crops (ISAAA, 2007) but are also widely 6 exploited as biopesticides with target hosts ranging from mosquitoes to lepidopteran 7 pests of horticulture and foresty (Glare and O'Callaghan, 2000). Although the 8 structure and mode of action of Bt Cry toxins has been intensively researched, the 9 biology and ecology of the bacterium is not fully characterized (Jensen et al., 2003; 10 Raymond et al., 2008a). Disagreement on the biology of Bt extends to the exact 11 mechanism responsible for the death of the host. A purely toxin based hypothesis 12 Persistence of antibiotics in larval tissues was implicated in reducing hostsuggests that the action of predominantly Cry toxins paralyses the mid-gut and leads 13 to eventual death by starvation (Knowles, 1994). Alternatively, Cry toxins cause 14 extensive cell lysis in the mid-gut that allows bacteria access to the haemolymph, thus 15 rapid vegetative growth of Bt within the host (septicaemia) is proposed as an 16 alternative cause of death (Schnepf et al., 1998). 17Recently, a novel pathogenic mechanism was suggested by the claim that Bt 18 and its toxins are incapable of killing aseptically reared gypsy moth, Lymantria 19 dispar, larvae but that pathogenicity can be restored by inoculating hosts with a gut-20 associated strain of Enterobacter (Broderick et al., 2006). More recent work has 21 extended this claim to a wide range of insect hosts (Broderick et al., 2009). An 22 obligate association with the gut microbiota challenges previous models of the 23 pathogenicity of Bt toxins, and has considerable implications for the ecology of Bt and 24 the evolution of novel resistance mechanisms in invertebrate pests. The gut 25

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Section: Introductionmentioning

confidence: 99%

A mid‐gut microbiota is not required for the pathogenicity of Bacillus thuringiensis to diamondback moth larvae

Raymond

Johnston

Wright

et al. 2009

Environmental Microbiology

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“…kurstaki, but not with Bt subsp. aizawai (Liu et al, 1998). Helicoverpa armigera (Hübner) larvae feeding on a diet with the same antibiotic cocktail as reported by Broderick et al (2006Broderick et al ( , 2010 did not develop resistance to Cry1Ab or Cry1Ac after transgenerational Bt exposure, but mortality was reduced 30% in the F3 generation of insects reared on antibiotics-free diet and exposed to Bt (Paramasiva et al, 2014).…”

Section: Discussionmentioning

confidence: 87%

Regulation by gut bacteria of immune response, Bacillus thuringiensis susceptibility and hemolin expression in Plodia interpunctella

Orozco-Flores

Valadéz-Lira

Oppert

et al. 2017

Journal of Insect Physiology

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Plodia interpunctella (Hübner) is an important stored grain insect pest worldwide, and the first lepidopteran with reported resistance to Bacillus thuringiensis (Bt) toxins. Since gut bacteria may affect Bt insecticidal activity, we evaluated whether P. interpunctella lacking gut bacteria had differences in immune responses and susceptibility to the Bt formulation, Bactospeine. In order to clear gut bacteria, third instar larvae were reared on artificial diet containing antibiotics, or were obtained from sterilized eggs and reared under sterile conditions, and larvae were fed diets with or without Bt. Mortality was significantly lower (p<0.05) in bacteria-free larvae treated with Bt, compared with Bt-treated larvae with unaffected gut bacteria. The number of hemocytes was lower in control and Bt-treated larvae, but was significantly higher (p<0.001) in larvae treated with antibiotics and Bt, and larvae from presterilized eggs and reared on sterile diet had the highest number of hemocytes. Phenoloxidase activity was significantly lower (p<0.05) in Bt-treated larvae from presterilized eggs reared on antibiotics for 24h or in larvae reared on antibiotic-treated diets prior to Bt introduction compared with those fed control diet. Hemolin gene expression was reduced in larvae fed Bt diets compared with control and was not detected in larvae treated with antibiotics. Larvae from sterilized eggs and fed sterile diet never reached the pupal stage. Therefore, the loss of gut bacteria in P. interpunctella larvae affected the host immune response and expression of the hemolin gene, and significantly reduced susceptibility to Bt.

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“…To pyramid transgenes in such clonal crops therefore requires either simultaneous transformation or retransformation approaches. It is important first to investigate how the expression of two dissimilar cry genes might interact in transgenic plants because Bt toxins can interact, with antagonistic (Lee et al , 1996; Del Rincón‐Castro et al , 1999), additive (Poncet et al , 1995) and synergistic (Tabashnik, 1992; Poncet et al , 1995; Lee et al , 1996; Liu et al , 1998) effects.…”

Section: Discussionmentioning

confidence: 99%

“…Such interaction studies have shown the synergistic effects of the Bt toxins on certain pests (e.g. Tabashnik, 1992; Poncet et al , 1995; Lee et al , 1996; Liu et al , 1998). However, the majority of such studies have been based on the use of either partially or wholly purified crystal proteins and spores of Bt .…”

Section: Introductionmentioning

confidence: 99%

An experimental approach to simulate transgene pyramiding for the deployment of cry genes to control potato tuber moth (Phthorimaea operculella)

Meiyalaghan

Butler

Wratten

et al. 2006

Annals of Applied Biology

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Alternating the daily feeding of potato tuber moth (Phthorimaea operculella) larvae (PTM) between isogenic pairs of potato plants provides an effective experimental approach to simulate transgene pyramiding in a clonal crop. This involves an experimental design with all six possible pairwise combinations of two transgenic lines expressing different cry genes and the nontransgenic control. In this manner, we have simulated the pyramiding of pairwise combinations of cry1Ac9, cry9Aa2 and cry1Ba1 genes in potato and evaluated how pairs of these three cry genes interact to influence the growth rate of PTM larvae. The results show that all combinations of the three cry genes were largely consistent with additive impacts on PTM larval growth, although results from the combination of the cry1Ac9 and cry9Aa2 genes were suggestive of slight synergistic effects. Pyramiding the cry1Ac9, cry9Aa2 and cry1Ba1 genes in potato could therefore provide a more effective strategy to control PTM compared to single cry gene transgenic plants.

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Synergism between Bacillus thuringiensis Spores and Toxins against Resistant and Susceptible Diamondback Moths ( Plutella xylostella )

Cited by 42 publications

References 33 publications

A mid‐gut microbiota is not required for the pathogenicity of Bacillus thuringiensis to diamondback moth larvae

A mid‐gut microbiota is not required for the pathogenicity of Bacillus thuringiensis to diamondback moth larvae

Regulation by gut bacteria of immune response, Bacillus thuringiensis susceptibility and hemolin expression in Plodia interpunctella

An experimental approach to simulate transgene pyramiding for the deployment of cry genes to control potato tuber moth (Phthorimaea operculella)

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