Isolation and Characterization of Photorhabdus Spp. (Enterobacteriaceae) Isolated From Heterorhabditis Bacteriophora in Kashere, Nigeria

Photorhabdus bacteria are symbiotically associated with the infective juveniles of entomopathogenic nematodes of the genus Heterorhabditis. These bacteria after infecting a susceptible host, produces a host of lethal toxins that killthe insect hosts within 24 to 72 hours. Consequently they have emerged and are trending as excellent biological control agents against insect pests of agricultural crops. Therefore, this study aim to isolate, identify and test the pathogenicity of Photorhabdus bacteria isolated from Heterorhabditis bacteriophora, entomopathogenic nematode from Kashere, Gombe State, Nigeria. To this end phenotypic and biochemical tests were conducted. The tests conducted showed that the isolate exhibited characteristics similar to those of Photorhabdus bacteria that have been identified. Last instar larvae of G. mellonella exposed to different concentrations of the bacterial isolate showed some level of susceptibility of the larvae to the bacterial isolate confirming its biological control potential.

Selection of suitable predatory mites against, Panonychus citri (McGregor) (Acari: Tetranychidae) using relative control potential metrics and functional response

Background Selection of suitable predators for the control of the spider mite, Panonychus citri is always a challenge due to the lack of their reliable predicted efficacy. In this laboratory study, biological control potential of Neoseiulus californicus, N. cucumeris and Scapulaseius newsami, against P. citri using the “Relative Control Potential” (RCP) metric to compare their efficacies was evaluated. The functional response type was determined at different prey densities (after 24 h). Results The type II functional responses were observed from all the tested predators feeding on 3 different life stages of P. citri, except N. cucumeris, which was fed only on eggs. All predatory mites preferred eggs of P. citri with a higher attack rate (1.397) in N. cucumeris, followed by N. californicus (1.238) and S. newsami (0.975). Handling time was also lower in N. cucumeris than other mites, with a trend as: for N. cucumeris, eggs > adults > immature stages; for N. californicus, immature stages > eggs > adults, while for S. newsami, eggs > immature stages > adults. The integration of greenhouse abundance and fecundity (%) data resulted in a higher RCP for N. cucumeris than other predators. Conclusion Neoseiulus cucumeris was selected as the most suitable predatory mite for the control of P. citri with a higher RCP and potential to maximum reproduction. S. newsami, which was used for the first time, gave almost similar results compared to N. californicus but with lower efficacy.

High-quality complete genome resource of tomato rhizosphere strain Pseudomonas donghuensis P482, a representative of a species with biocontrol activity against plant pathogens

Strain P482 was isolated from a tomato rhizosphere and classified as Pseudomonas donghuensis. The P. donghuensis species was first established in 2015 and currently comprises only four strains: P482, HYST, SVBP6, and 22G5. P. donghuensis strains antagonize plant pathogens, including bacteria, fungi and oomycetes, and therefore are of high interest regarding their biological control potential to combat plant diseases. The antimicrobial activity of P. donghuensis P482 is based on the production of iron scavenging compound 7-hydroxytropolone, antifungal volatile organic compounds, and yet unidentified secondary metabolite(s). Here, we report a complete genome resource for P. donghuensis strain P482. The genome consists of a single chromosome (5 656 185 bp) with 5258 ORFs (5158 protein-coding genes, 74 tRNAs, 22 rRNAs, 3 ncRNAs and 1 tmRNA) and no plasmid. We believe that the information of the first high-quality, complete genome of P. donghuensis will provide resources for analyses targeting the biological control potential of this species and understanding the traits essential for plant-microbe interaction.

Assessment of Sugarcane Genotypes for Red Rot Resistance and Antifungal Activity of Rhizosphere Microbiota against Colletotricum falcatum

The aim of this study was to screen the potential of locally grown sugarcane genotypes for red rot resistance and activity of native microbial strains against the pathogen. Field trials were conducted with 70 genotypes for consecutive years and results showed that only two genotypes viz., SSRI-1 and CO-0238 showed resistant behavior towards red rot of sugarcane. The red rot pathogen Colletotrichum falcatum Went was characterized and pathogenicity tests on two susceptible genotypes (NSG-59 and CPSG-2923) showed high virulence of SUCF04 isolate to develop severe disease lesions. The native rhizospheric microbiota was screened for microbial consortia exhibiting fine antifungal activity against the highly virulent pathogenic strain. The antagonism assay exposed that 10 bacterial isolates out of 46 showed great potential for antifungal activity. The selected bacterial isolates revealed 68–99% pathogen inhibition during the assay. The fungal strains with biological control potential inhibited the pathogen growth by 20–80% and a group of three strains with more than 50% antifungal activity were characterized. The molecular characterization of these microbes revealed that the isolates were belonging to Bacillus subtilus, Pseudomonas putida, Pseudomonas fluorescence, Trichoderma harzianum and several other important taxa. This study revealed that only two sugarcane genotypes were found as resistant against red rot pathogen, while most of the genotypes showed susceptible to moderately susceptible response. Moreover, the native residential microbiota associated with sugarcane exhibited great antifungal potential and can be utilized for disease protection and improved crop productivity. © 2021 Friends Science Publishers

High-quality complete genome resource of tomato rhizosphere strain Pseudomonas donghuensis P482, a representative of a species with biocontrol activity against plant pathogens

Strain P482 was isolated from a tomato rhizosphere and classified as Pseudomonas donghuensis. The P. donghuensis species was first established in 2015 and currently comprises only four strains: P482, HYST, SVBP6, and 22G5. P. donghuensis strains antagonize plant pathogens, including bacteria, fungi and oomycetes, and therefore are of high interest regarding their biological control potential to combat plant diseases. The antimicrobial activity of P. donghuensis P482 is based on the production of iron scavenging compound 7-hydroxytropolone, antifungal volatile organic compounds, and yet unidentified secondary metabolite(s). Here, we report a complete genome resource for P. donghuensis strain P482. The genome consists of a single chromosome (5 656 185 bp) with 5258 ORFs (5158 protein-coding genes, 74 tRNAs, 22 rRNAs, 3 ncRNAs and 1 tmRNA) and no plasmid. We believe that the information of the first high-quality, complete genome of P. donghuensis will provide resources for analyses targeting the biological control potential of this species and understanding the traits essential for plant-microbe interaction.

Augmenting Nesidiocoris tenuis (Nesidiocoris) with a Factitious Diet of Artemia Cysts to Control Bemisia tabaci (Gennadius) on Tomato Plants under Greenhouse Conditions

Natural predators such as Nesidiocoris tenuis are known for their role in managing greenhouse pests. However, techniques in maximizing the biological control potential of N. tenuis under field conditions are still lacking. We evaluated under greenhouse conditions the prospects of Artemia cysts enhanced with high fructose corn syrup and honey, and delivered using hemp strings (hemp rope) as supplementary factitious dietary in augmenting the proliferation and spread of N. tenuis on tomato plants. Results showed that N. tenuis supplemented with hemp rope could establish, proliferate and disperse among tomato plants compared to the N. tenuis supplemented with banker plants. Even though N. tenuis proliferated exponentially on banker plants, their movement and relocation to tomato plants, as expected, were only congested on tomato plants near the banker plants. However, as the survey continued, they relocated to the rest of the tomato plants. Furthermore, the number of Bemisia tabaci eggs and nymphs, a serious greenhouse pest of tomato, was observed to be significantly reduced in hemp rope greenhouse compared to banker plants and the negative control (no pest control system) greenhouses. This study, therefore, establishes foundational data on the usage of Artemia cysts enhanced with isomerized sugar (high fructose corn syrup) and honey under greenhouse conditions as factitious supplementary dietary in supporting N. tenuis establishment and spread, traits that are essential towards development of whitefly Integrated Pest Management (IPM) system. enhanced with isomerized sugar (high fructose corn syrup) and honey.