Insecticidal potential of Brevibacillus laterosporus against dipteran pest species in a wide ecological range

Bedini, Stefano; Muniz, Elen Regozino; Tani, Chiara; Conti, Bárbara; Ruiu, Luca

doi:10.1016/j.jip.2020.107493

Cited by 17 publications

(10 citation statements)

References 25 publications

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“…Lethal effects were concentration-dependent, as normally expected for entomopathogenic bacteria acting by ingestion on these target insects [11]. LC50 values are comparable with those observed on other entomopathogenic bacteria with similar mode of action and effective on muscoid flies [12]. Our experiments conducted injecting bacterial cells in the house fly larvae haemocoel, showed that P. protegens reproduces well in the hemolymph, which represents a natural target substrate ultimately allowing the bacterium to express its biotic potential.…”

Section: Discussionsupporting

confidence: 76%

Oral Toxicity of Pseudomonas protegens against Muscoid Flies

Ruiu

Mura

2021

Toxins

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The bioinsecticidal action of Pseudomonas protegens has so far been reported against some target insects, and the mode of action remains unclear. In this study, the pathogenicity potential of a recently isolated strain of this bacterial species against fly larvae of medical and veterinary interest was determined. Preliminary experiments were conducted to determine the biocidal action by ingestion against Musca domestica and Lucilia caesar larvae, which highlighted a concentration-dependent effect, with LC50 values of 3.6 and 2.5 × 108 CFU/mL, respectively. Bacterial septicaemia was observed in the body of insects assuming bacterial cells by ingestion. Such rapid bacterial reproduction in the hemolymph supports a toxin-mediated mechanism of action involving the intestinal barrier overcoming. In order to gain more information on the interaction with the host, the relative time-course expression of selected P. protegens genes associated with virulence and pathogenicity, was determined by qPCR at the gut level during the first infection stage. Among target genes, chitinase D was the most expressed, followed by pesticin and the fluorescent insecticidal toxin fitD. According to our observations and to the diversity of metabolites P. protegens produces, the pathogenic interaction this bacterium can establish with different targets appears to be complex and multifactorial.

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Section: Discussionsupporting

confidence: 76%

Oral Toxicity of Pseudomonas protegens against Muscoid Flies

Ruiu

Mura

2021

Toxins

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“…Brevibacillus laterosporus ( Bl ) is a Gram-positive and spore-forming bacterium belonging to the Brevibacillus brevis phylogenetic cluster in the family Paenibacillaceae [ 1 ]. Globally, various strains of this bacterium have exhibited biocontrol potential against invertebrate pests of different insect orders, including Coleoptera [ 2 , 3 ], Diptera [ 4 , 5 , 6 ], Lepidoptera [ 7 ], and also against nematodes [ 8 ] and molluscs [ 9 , 10 ]. The insecticidal action is mostly related to the production of diverse toxins, many of which act post-ingestion in the insect gut [ 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Isolation, Purification, and Characterisation of a Phage Tail-Like Bacteriocin from the Insect Pathogenic Bacterium Brevibacillus laterosporus

et al. 2022

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The Gram-positive and spore-forming bacterium Brevibacillus laterosporus (Bl) belongs to the Brevibacillus brevis phylogenetic cluster. Isolates of the species have demonstrated pesticidal potency against a wide range of invertebrate pests and plant diseases. Two New Zealand isolates, Bl 1821L and Bl 1951, are under development as biopesticides for control of diamondback moth and other pests. However, due to the often-restricted growth of these endemic isolates, production can be an issue. Based on the previous work, it was hypothesised that the putative phages might be involved. During investigations of the cause of the disrupted growth, electron micrographs of crude lysate of Bl 1821L showed the presence of phages’ tail-like structures. A soft agar overlay method with PEG 8000 precipitation was used to differentiate between the antagonistic activity of the putative phage and phage tail-like structures (bacteriocins). Assay tests authenticated the absence of putative phage activity. Using the same method, broad-spectrum antibacterial activity of Bl 1821L lysate against several Gram-positive bacteria was found. SDS-PAGE of sucrose density gradient purified and 10 kD MWCO concentrated lysate showed a prominent protein band of ~48 kD, and transmission electron microscopy revealed the presence of polysheath-like structures. N-terminal sequencing of the ~48 kD protein mapped to a gene with weak predicted amino acid homology to a Bacillus PBSX phage-like element xkdK, the translated product of which shared >90% amino acid similarity to the phage tail-sheath protein of another Bl published genome, LMG15441. Bioinformatic analysis also identified an xkdK homolog in the Bl 1951 genome. However, genome comparison of the region around the xkdK gene between Bl 1821L and Bl 1951 found differences including two glycine rich protein encoding genes which contain imperfect repeats (1700 bp) in Bl 1951, while a putative phage region resides in the analogous Bl 1821L region. Although comparative analysis of the genomic organisation of Bl 1821L and Bl 1951 PBSX-like region with the defective phages PBSX, PBSZ, and PBP 180 of Bacillus subtilis isolates 168 and W23, and Bacillus phage PBP180 revealed low amino acids similarity, the genes encode similar functional proteins in similar arrangements, including phage tail-sheath (XkdK), tail (XkdO), holin (XhlB), and N-acetylmuramoyl-l-alanine (XlyA). AMPA analysis identified a bactericidal stretch of 13 amino acids in the ~48 kD sequenced protein of Bl 1821L. Antagonistic activity of the purified ~48 kD phage tail-like protein in the assays differed remarkably from the crude lysate by causing a decrease of 34.2% in the number of viable cells of Bl 1951, 18 h after treatment as compared to the control. Overall, the identified inducible phage tail-like particle is likely to have implications for the in vitro growth of the insect pathogenic isolate Bl 1821L.

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“…The relative toxicity of the EOs was assessed, using probit analysis [46,47], by calculating the median lethal concentration (LC 50 ) for the ingestion and fumigation tests and the median lethal dose (LD 50 ) for the contact test. For each toxicity test, a probit model was built for the three EOs.…”

Section: Discussionmentioning

confidence: 99%

Andean Plants Essential Oils: A Scented Alternative to Synthetic Insecticides for the Control of Blowflies

Farina

Venturi

Ascrizzi

et al. 2021

Insects

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Blowflies are vectors of microorganisms and human pathogens, and their maggots cause myiasis in vertebrates and infest and spoil meat and fish products. Essential oils (EOs) from spices were proven to be a safer and more sustainable alternative to synthetic insecticides for the control of blowflies and are suitable for protecting food from such pests. However, some EOs are not acceptable for environmental or topical applications due to their strong, unpleasant odour. In this study, we measured the acute toxicity and the repellence of two EOs extracted from the Andean plants Aloysia citrodora Palau and Bursera graveolens (Kunth) Triana and Planch., both known for their pleasant odour, against the blue blowfly Calliphora vomitoria (L.) (Diptera: Calliphoridae). We also compared their bioactivity with that of the Allium sativum L. EO, which is very effective but bad-smelling. The A. citrodora EO was mainly rich in oxygenated monoterpenes, the most abundant of which were geranial (26.8%) and neral (21.0%). The B. graveolens EO was chiefly composed of monoterpene hydrocarbons, mostly represented by limonene (46.2%). According to the sensory description, the best odour profile was associated with the A. citrodora EO, while the olfactory expression of the EO from B. graveolens was negatively affected by a strong odour of “mouldy lemon”. The behavioural test showed that the A. citrodora EO was more repellent than that of A. sativum and, on the contrary, that the B. graveolens EO was attractive. The toxicity tests showed that the EOs of both Andean plants have a clear toxic effect on the C. vomitoria eggs and adults. In terms of ovicidal activity, there were no significant differences among the effects of the three tested EOs. On the adult flies, the toxicity of the two EOs of the Andean plants was much lower than that of A. sativum (LC50 fumigation = 1.86 μL EO L−1 air; LC50 ingestion = 8.10 μL EO mL−1 gel) both by fumigation (LC50 = 23.66 and 25.30 μL EO L−1 air for A. citrodora and B. graveolens, respectively) and ingestion (LC50 = 36.65 and 44.97 μL EO mL−1 gel for A. citrodora and B. graveolens, respectively), while, by contact, the A. citrodora EO (LD50 = 0.27 μL EO insect−1) was more toxic than the A. sativum EO (LD50 = 0.46 μL EO insect−1).

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Insecticidal potential of Brevibacillus laterosporus against dipteran pest species in a wide ecological range

Cited by 17 publications

References 25 publications

Oral Toxicity of Pseudomonas protegens against Muscoid Flies

Oral Toxicity of Pseudomonas protegens against Muscoid Flies

Isolation, Purification, and Characterisation of a Phage Tail-Like Bacteriocin from the Insect Pathogenic Bacterium Brevibacillus laterosporus

Andean Plants Essential Oils: A Scented Alternative to Synthetic Insecticides for the Control of Blowflies

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