Induction of Antibacterial Activity against Bacillus thuringiensis in the Common Cutworm, Spodoptera litura(Lepidoptera : Noctuidae)

Inagaki, Soichi; Miyasono, Minoru; Yamamoto, Makiko; Ohba, Katsuaki; Ishiguro, Takeo; Takeda, Reiji; Hayashi, Yoshiyuki

doi:10.1303/aez.27.565

Cited by 9 publications

(5 citation statements)

References 9 publications

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“…Bacillus thuringiensis is highly resistant to the humoral defence system of the host, especially to cecropins and attacins, which are the main classes of inducible antibacterial peptides in various lepidopterans and dipterans (Hultmark et al, 1982;Inagaki et al, 1992). An extracellular zinc metalloprotease, termed InhA or InA (immune inhibitor A) which specifically hydrolyzes antibacterial proteins produced by the insect host, in vitro, was suggested to partly explain the success of the bacterium in invading hemocoel (Dalhammar and Steiner, 1984).…”

Section: Proteases Phospholipasesmentioning

confidence: 99%

Bacillus thuringiensis beyond insect biocontrol: plant growth promotion and biosafety of polyvalent strains

et al. 2007

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The entomopathogenic bacterium Bacillus thuringiensis is widely used for the control of many agricultural insect pests and vectors of human diseases. Several studies reported also on its antibacterial and antifungal activities. However, to our knowledge there were no studies dealing with its capacity to act as a plant growth promoting bacterium. This review surveys the potential of B. thuringiensis as a polyvalent biocontrol agent, a biostimulator and biofertiliser bacterium that could promote the plant growth. Also, discussed is the safety of B. thuringiensis as a bacterium phylogenetically closely related to Bacillus cereus the opportunistic human pathogen and Bacillus anthracis, the etiological agent of anthrax.

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Section: Proteases Phospholipasesmentioning

confidence: 99%

Bacillus thuringiensis beyond insect biocontrol: plant growth promotion and biosafety of polyvalent strains

et al. 2007

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“…We do not know how B. thuringiensis cells or spores manage to invade and to kill insects after hemocoelic inoculation. However, B. thuringiensis is highly resistant to the humoral defense system of the host, especially to cecropins and attacins, which are the main classes of inducible antibacterial peptides in various lepidopterans and dipterans (5,23,24). A zinc metalloprotease secreted by B. thuringiensis, termed InhA or InA, specifically hydrolyzes cecropins and attacins in the immune hemolymph of Hyalophora cecropia in vitro (8,12).…”

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confidence: 99%

The InhA2 Metalloprotease of Bacillus thuringiensis Strain 407 Is Required for Pathogenicity in Insects Infected via the Oral Route

2002

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The entomopathogenic bacterium Bacillus thuringiensis is known to secrete a zinc metalloprotease (InhA) that specifically cleaves antibacterial peptides produced by insect hosts. We identified a second copy of the inhA gene, named inhA2, in B. thuringiensis strain 407 Cry ؊ . The inhA2 gene encodes a putative polypeptide showing 66.2% overall identity with the InhA protein and harboring the zinc-binding domain (HEXXH), which is characteristic of the zinc-requiring metalloproteases. We used a transcriptional inhA2-lacZ fusion to show that inhA2 expression is induced at the onset of the stationary phase and is overexpressed in a Spo0A minus background. The presence of a reverse Spo0A box in the promoter region of inhA2 suggests that Spo0A directly regulates the transcription of inhA2. To determine the role of the InhA and InhA2 metalloproteases in pathogenesis, we used allelic exchange to isolate single and double mutant strains for the two genes. Spores and vegetative cells of the mutant strains were as virulent as those of the parental strain in immunized Bombyx mori larvae infected by the intrahemocoelic route. Exponential phase cells of all the strains displayed the same in vitro potential for colonizing the vaccinated hemocoel. We investigated the synergistic effect of the mutant strain spores on the toxicity of Cry1C proteins against Galleria mellonella larvae infected via the oral pathway. The spores of ⌬inhA2 mutant strain were ineffective in providing synergism whereas those of the ⌬inhA mutant strain were not. These results indicate that the B. thuringiensis InhA2 zinc metalloprotease has a vital role in virulence when the host is infected via the oral route.

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“…We speculate that ingestion of the dose in a single droplet is more lethal to a spruce budworm larva than repeated ingestion of lower doses partly because dose ingestion within a short time may overwhelm the larva's ability to recover from pathological effects. More detailed knowledge of recovery processes, such as aggregation of toxin protein at the peritrophic membrane (Bravo et al 1992), the ability to regenerate damaged midgut cells (Spies and Spence 1985), or the ability to arrest bacterial growth through inducible humoral defenses (Inagaki et al 1992), and their dose-dependence, may shed further light on our observations. It is also possible that the amount of needle tissue consumed plays a role by diluting or inactivating the toxic moiety.…”

Section: Discussionmentioning

confidence: 89%

EFFECT OF SPRAY DROPLET SIZE AND DENSITY ON EFFICACY OF BACILLUS THURINGIENSIS BERLINER AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE)

Payne

Frankenhuyzen

1995

Can Entomol

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Because microbial insecticides based on Bacillus thuringiensis subsp. kurstaki cause temporary cessation of larval feeding at sublethal doses, we hypothesized that the delivery of a given dose in a single droplet is more efficacious than delivery of the same dose in multiple smaller droplets. We tested this hypothesis by exposing larvae of the spruce budworm, Choristoneura fumiferana (Clem.), to an LD50 of a commercial product (Dipel 8L) in combinations of droplet sizes and densities that are commonly observed on coniferous foliage after aerial application. A nominal dose of 5.2 International Units (IU) was presented to fifth-instar larvae on one, two, or four balsam fir, Abies balsamea L., needles in the form of one, two, or four droplets with diameters of 84, 66, or 52 μm, respectively. The combinations of droplet size and density were chosen to represent an increasing degree of dose dispersion. Overall mortality after a 24-h exposure was significantly reduced with increasing dose dispersion from an average of 66% when the dose was presented in one 84-μm droplet on one needle to 40% when presented in multiple droplets on several needles. Increased dose dispersion reduced the proportion of larvae that were able to ingest the full dose, presumably because of feeding inhibition caused by ingestion of sublethal droplets. In addition, mortality of fully dosed larvae declined significantly with increasing dispersion, implying a reduction in the effectiveness of the ingested dose. When compared with operational spray deposits, our results suggest that efficacy of spruce budworm sprays may be improved by increasing the proportion of needles receiving a lethal spray deposit by increasing product potency and possibly the active ingredient application rate.

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Induction of Antibacterial Activity against Bacillus thuringiensis in the Common Cutworm, Spodoptera litura(Lepidoptera : Noctuidae)

Cited by 9 publications

References 9 publications

Bacillus thuringiensis beyond insect biocontrol: plant growth promotion and biosafety of polyvalent strains

Bacillus thuringiensis beyond insect biocontrol: plant growth promotion and biosafety of polyvalent strains

The InhA2 Metalloprotease of Bacillus thuringiensis Strain 407 Is Required for Pathogenicity in Insects Infected via the Oral Route

EFFECT OF SPRAY DROPLET SIZE AND DENSITY ON EFFICACY OF BACILLUS THURINGIENSIS BERLINER AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE)

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