Characterization and pathogenicity of symbiotic bacteria associated with entomopathogenic nematode: Steinernema species KALRO

The soil inhibiting entomopathogenic nematodes (EPNs), in the family Steinernematidae and Heterorhabditidae, are useful insect biological control agents. They have been used in the management of economically important crop pests. The EPNs are mutually associated with symbiotic bacteria genus Xenorhabdus and Photoharbdus respectively. The study aimed to isolate, characterize and evaluate the pathogenicity of symbiotic bacteria associated with EPN Steinernema sp. Kalro (Accession MW151701). The EPN Steinernema sp. Karlo was multiplied using the insect baiting technique. Its bacteria symbiont was isolated and characterized based on microscopic, biochemical, and physiological features like Gram staining, urease, motility test, and glucose fermentation test). Molecular identification and phylogenetic analysis were performed on 16S rDNA nucleotide sequence. Pathogenicity of the bacteria isolate was evaluated against Tuta absoluta larvae with mortality data recorded after 24 and 48hours of exposure to the bacterial cell suspension. The bacteria were found to be motile and glucose fermentation positive. Sequence analysis of 16S rDNA region resulted in 1500bp sequence with maximum similarity of between 97 and 98.93%, with Xenorhabdus spp Accessions from Genbank. It closely matched to Xenorhabdus sp. My8NJ with 98.93% similarity (Accession AB507811.1). Mean percent larval mortality of 68±4.9 and 88±8.0 in the lowest cell suspension was observed in 24 and 48h of exposure. It’s concluded that, the symbiotic bacteria associated with Steinernema sp. Kalro is Xenorhabdus sp. strain Kalro Genbank Accession MW245845. The bacteria is a potential biological control agent against Tuta absoluta larvae. Further classification of the bacteria to species level and pathogenicity trials in the screen house and field are recommended.

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Trichogramma cacoeciae as a biological control agent of the tomato pinworm Tuta absoluta in Northeastern Tunisia

ENTOMOLOGIA HELLENICA ◽

10.12681/eh.11527 ◽

2017 ◽

Vol 22 (2) ◽

pp. 35 ◽

Cited By ~ 4

Author(s):

Asma Cherif ◽

Lebdi Grissa Kaouthar

Keyword(s):

Biological Control ◽

Biological Control Agent ◽

Control Agent ◽

Tuta Absoluta ◽

Trichogramma Cacoeciae ◽

Promising Agent ◽

The World ◽

Northeastern Tunisia ◽

Eggs And Larvae ◽

Tomato Pinworm

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is considered as key pest attacking tomato in Tunisia and in many other countries around the world. In order to investigate the efficacy of Trichogramma cacoeciae (Marchal) (Hymenoptera: Trichogrammatidae) for biological control of this pest in Northeastern Tunisia, releases were performed in open field conditions. T. cacoeciae showed a good efficacy on reducing the number of T. absoluta eggs and larvae when releasing 30 adults/plant in plots covered with insect-proof netting in May 2012. The results showed that this parasitoid may be a promising agent for T. absoluta biological control in Tunisia.

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Seasonal activity, habitat preferences and larval mortality of the leaf-mining flyCalycomyza eupatorivora(Agromyzidae), a biological control agent established onChromolaena odorata(Asteraceae) in South Africa

Biocontrol Science and Technology ◽

10.1080/09583157.2014.935293 ◽

2014 ◽

Vol 24 (11) ◽

pp. 1297-1307 ◽

Cited By ~ 2

Author(s):

Sindisiwe Nzama ◽

Terence Olckers ◽

Costas Zachariades

Keyword(s):

South Africa ◽

Biological Control ◽

Biological Control Agent ◽

Larval Mortality ◽

Habitat Preferences ◽

Control Agent ◽

Seasonal Activity ◽

Leaf Mining

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Biological Control of Grape Crown Gall by Rahnella aquatilis HX2

Plant Disease ◽

10.1094/pdis-91-8-0957 ◽

2007 ◽

Vol 91 (8) ◽

pp. 957-963 ◽

Cited By ~ 43

Author(s):

F. Chen ◽

Y. B. Guo ◽

J. H. Wang ◽

J. Y. Li ◽

H. M. Wang

Keyword(s):

Biological Control ◽

Cell Suspension ◽

Crown Gall ◽

Biological Control Agent ◽

Disease Incidence ◽

Significant Inhibition ◽

Agrobacterium Vitis ◽

Rahnella Aquatilis ◽

Inhibition Effect ◽

Significant Difference

Crown gall induced by Agrobacterium vitis is a worldwide plant disease in grape-growing regions. Rahnella aquatilis HX2, a new isolate from vineyard soil in Beijing, showed a significant inhibition effect on the development of crown galls in grapevines. In field trials, immersion of the basal ends of grape cuttings with HX2 cell suspension inhibited or completely prevented crown gall formation caused by A. vitis K308 in the roots of the plants from the cuttings. The 3-year average disease incidence in grape plants treated with HX2 was 30.8% compared to 93.5% in plants without HX2. The culture supernatant of HX2 exhibited a stronger inhibition effect on disease development than did the cell suspension. HX2 could be found in the grape rhizosphere, grown under field conditions, for up to 90 days after inoculation. There was no significant difference in the mean population sizes of root microflora between plants treated and not treated with HX2. The inhibition effect of HX2 on crown gall in sunflower, caused by different agrobacterial strains, varied between 30.7 and 100%, depending on strains. Our results showed that Rahnella aquatilis HX2 may be used as a biological control agent for crown gall disease of grapes.

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dsRNA-Mediated Pest Management of Tuta absoluta Is Compatible with Its Biological Control Agent Nesidiocoris tenuis

Insects ◽

10.3390/insects12040274 ◽

2021 ◽

Vol 12 (4) ◽

pp. 274

Author(s):

Nomi Sarmah ◽

Athanasios Kaldis ◽

Clauvis Nji Tizi Taning ◽

Dionysios Perdikis ◽

Guy Smagghe ◽

...

Keyword(s):

Biological Control ◽

Integrated Pest Management ◽

Pest Management ◽

Biological Control Agent ◽

Insect Pest ◽

Tuta Absoluta ◽

Oral Exposure ◽

Worst Case ◽

Insect Management ◽

Nesidiocoris Tenuis

RNAi-mediated insect pest management has recently shown promising results against the most serious pest of tomato, the tomato leafminer, Tuta absoluta. This study aimed to investigate whether dsRNA (dsTa-αCOP) designed to target the T. absoluta-αCOP gene could cause adverse effects to its biocontrol agent, the mirid predator, Nesidiocoris tenuis. Oral exposure of N. tenuis to dsRNA (dsNt-αCOP) designed to target N. tenuis-αCOP resulted in a 61%, 67% and 55% reduction in its transcript level in comparison to the sucrose, dsGFP and dsTa-αCOP treatments, respectively. In addition, significantly higher mortality of 57% was recorded in dsNt-αCOP-treated N. tenuis when compared to the sucrose (7%), dsGFP (10%) and dsTa-αCOP (10%) treatments. Moreover, the predation rate of ~33–39 Ephestia kuehniella eggs per N. tenuis adult dramatically reduced to almost half in the surviving dsNt-αCOP-treated N. tenuis. This worst-case exposure scenario confirmed for the first time that the RNAi machinery is functional in this species and that the risk of exposure through the oral route is possible. In contrast, dsTa-αCOP did not cause any sub-lethal effects to N. tenuis upon oral exposure. Oral exposure of T. absoluta to dsTa-αCOP resulted in 50% mortality. In the context of a biosafety risk assessment of RNAi-mediated insect management, investigating the effects on non-target organisms is essential in order to include this method as part of an integrated pest management strategy. Based on our laboratory assays, RNAi-mediated control is compatible with the biological control of T. absoluta by its natural enemy N. tenuis, adding the RNAi approach in the armoire of integrated pest management of T. absoluta.

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Exploring the Use of Entomopathogenic Nematodes and the Natural Products Derived from Their Symbiotic Bacteria to Control the Grapevine Moth, Lobesia botrana (Lepidoptera: Tortricidae)

Insects ◽

10.3390/insects12111033 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1033

Author(s):

Ignacio Vicente-Díez ◽

Rubén Blanco-Pérez ◽

Maryam Chelkha ◽

Miguel Puelles ◽

Alicia Pou ◽

...

Keyword(s):

Biological Control ◽

Natural Products ◽

Bioactive Compounds ◽

Entomopathogenic Nematodes ◽

Larval Mortality ◽

Lobesia Botrana ◽

Symbiotic Bacteria ◽

Biological Control Agents ◽

Larval Instars ◽

Grapevine Moth

The European grapevine moth (EGVM) Lobesia botrana (Lepidoptera: Tortricidae) is a relevant pest in the Palearctic region vineyards and is present in the Americas. Their management using biological control agents and environmentally friendly biotechnical tools would reduce intensive pesticide use. The entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are well-known virulent agents against arthropod pests thanks to symbiotic bacteria in the genera Xenorhabdus and Photorhabdus (respectively) that produce natural products with insecticidal potential. Novel technological advances allow field applications of EPNs and those bioactive compounds as powerful bio-tools against aerial insect pests. This study aimed to determine the viability of four EPN species (Steinernema feltiae, S. carpocapsae, S. riojaense, and Heterorhabditis bacteriophora) as biological control agents against EGVM larval instars (L1, L3, and L5) and pupae. Additionally, the bioactive compounds from their four symbiotic bacteria (Xenorhabdus bovienii, X. nematophila, X. kozodoii, and Photorhabdus laumondii subsp. laumondii, respectively) were tested as unfiltered ferment (UF) and cell-free supernatant (CFS) against the EGVM larval instars L1 and L3. All of the EPN species showed the capability of killing EGVM during the larval and pupal stages, particularly S. carpocapsae (mortalities of ~50% for L1 and >75% for L3 and L5 in only two days), followed by efficacy by S. feltiae. Similarly, the bacterial bioactive compounds produced higher larval mortality at three days against L1 (>90%) than L3 (~50%), making the application of UF more virulent than the application of CFS. Our findings indicate that both steinernematid species and their symbiotic bacterial bioactive compounds could be considered for a novel agro-technological approach to control L. botrana in vineyards. Further research into co-formulation with adjuvants is required to expand their viability when implemented for aboveground grapevine application.

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Biological control of leaf disease of barley with Bacillus strain

Biologija ◽

10.6001/biologija.v63i3.3584 ◽

2017 ◽

Vol 63 (3) ◽

Cited By ~ 2

Author(s):

Larysa O. Kriuchkova

Keyword(s):

Biological Control ◽

Cell Suspension ◽

Information Needs ◽

Biological Control Agent ◽

Agar Plate ◽

Pathogenic Fungi ◽

Control Agent ◽

Systemic Resistance ◽

Plant Infection

A new Bacillus amyloliquefaciens subsp. plantarum strain IMV B-7404 was selected by an in-vitro agar plate assay as a potential biological control agent. The strain strongly inhibited the growth of 12 important plant pathogenic fungi. In growth chamber assays, the severity of spot blotch of barley decreased when culture filtrate was applied on leaves or was introduced into the plant growth medium before fungal inoculation. Apparently, the metabolites of strain IMV B-7404 play a role in disease prevention, which indicates that the strain can stimulate induced systemic resistance (ISR). When the cell suspension was sprayed onto leaves, the disease severity depended on environmental and, probably, some other conditions. We suggest that effective biological control by Bacillus-based products depends on spraying leaves with the cell suspension to co-ordinate with the process of plant infection by the pathogen. The ecological behaviour and biology of both the antagonist and the target pathogen are the key elements in enhancing the efficacy of biocontrol products. It is necessary to know the stage of infection that is most vulnerable. This information needs to be identified individually for each pathosystem and in relation to environmental conditions.

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